Lennox G40DF-36A-070X, G40DF-36A-045, G40DF-48B-070, G40DF-36B-090, G40DF-48C-090 Unit Information

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Page 1

G40DF(X)

Service Literature

Corp. 0113−L6

Revised 09−2006

G40DF(X) series units are mid−efficiency gas furnaces used for downflow applications only, manufactured with Lennox Duralok Plus heat exchangers formed of aluminized steel. G40DF(X) units are available in heating capacities of 44,000 to 135,000 Btuh and cooling applications up to 5 tons. Refer to Engineering Handbook for proper sizing.

Units are factory equipped for use with natural gas. Kits are available for conversion to LPG operation. G40DF(X) model units are equipped with a hot surface ignition surface. The G40DF(X) unit meets the California Nitrogen Oxides (NO

) Standards and California Seasonal Efficiency requirements. All units use a redundant gas valve to assure safety shut−off as required by C.S.A.

All specifications in this manual are subject to change. Procedures outlined in this manual are presented as a recommendation only and do not supersede or replace local or state codes. In the absence of local or state codes, the guidelines and procedures outlined in this manual (except where noted) are recommended only and do not constitute code.

TABLE OF CONTENTS

Introduction 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Specifications 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Blower Data 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

High Altitude 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Parts Identification 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I Unit Components 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

II Installation 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

III Start Up 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IV Heating System Service Checks 18. . . . . . . . . . . . . .

V Typical Operating Characteristics 20. . . . . . . . . . . . . .

VI Maintenance 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

VII Wiring and Sequence of Operation 23. . . . . . . . . . .

VIII SureLight Troubleshooting Guide 33. . . . . . . . . . . .

IMPORTANT

Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Installation and service must be performed by a qualified installer, service agency or the gas supplier.

WARNING

Electric shock hazard. Can cause injury or death. Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at disconnect switch(es). Unit may have multiple power supplies.

WARNING

Sharp edges. Be careful when servicing unit to avoid sharp edges which may result in personal injury.

Page 2

SPECIFICATIONS

Gas Heating

ModelNo.

G40DF

−24A−045

G40DF

−36A−045

G40DF

−36A−070

G40DF

−36B−090

G40DF

−48B−070

eat g

Performance

Low NO

Model No. −24A−045X − − − −36A−070X − − − − − −

Input− Btuh 44,000 44,000 66,000 88,000 66,000

Output− Btuh 36,000 35,000 53,000 71,000 53,000

AFUE 80.0% 80.0% 80.0% 80.0% 80.0%

Highstatic(CSA)− in.w.g. .50 .50 .50 .50 .50

Temperature rise range − _F 20 − 50 20 − 50 35 − 65 45 − 75 25 − 55

Connections

Flue connection − in. (round) 4 4 4 4 4

GaspipesizeIPS− in. 1/2 1/2 1/2 1/2 1/2

Indoor

Wheelnominaldiameter xwidth −in. 10 x 7 10 x 8 10 x 8 10 x 8 10 x 10

ower

Motoroutput − hp 1/5

1/3 1/3 1/3 1/2

Tons ofadd-oncooling 1.5 − 2 2 − 3 2 − 3 2 − 3 3 − 4

ShippingData lbs. − 1 package 121 126 132 146 139

Electricalcharacteristics 120 volts − 60 hertz − 1 phase (less than 12 amps)

SPECIFICATIONS

Gas Heating

ModelNo.

G40DF

−48C−090

G40DF

−48C−110

G40DF

−60C−110

G40DF

−60D−135

eat g

Performance

Low NO

Model No. −48C−090X − − − −60C−110X − − −

Input− Btuh 88,000 110,000 110,000 132,000

Output− Btuh 71,000 89,000 90,000 107,000

AFUE 80.0% 80.0% 80.0% 80.0%

Highstatic(CSA)− in.w.g. .50 .50 .50 .50

Temperature rise range − _F 45 − 75 45 − 75 35 − 65 40 − 70

Connections

Flue connection − in. (round) 4 4 4 4

GaspipesizeIPS− in. 1/2 1/2 1/2 1/2

Indoor

Wheelnominaldiameter xwidth −in. 10 x 10 10 x 10 11−1/2 x 10 11−1/2 x 10

ower

Motoroutput − hp 1/2

1/2 1* 1*

Tons ofadd-oncooling 3 − 4 2.5 − 4 4 − 5 4 − 5

ShippingData lbs. − 1 package 153 169 172 195

Electricalcharacteristics 120 volts − 60 hertz − 1 phase (less than 12 amps)

NOTE − Filters and provisions for mounting are not furnished and must be field provided.

Annual Fuel Utilization Efficiency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized furnaces.

*Some units may be equipped with 3/4 hp motors.

Page 3

OPTIONAL ACCESSORIES − MUST BE ORDERED EXTRA

A" Width Models B" Width Models C" Width Models D" Width Models

CABINET ACCESSORIES

Down−Flow Additive Base 11M59 11M60 11M61 11M62

CONTROLS

Twinning Kit 15L38 15L38 15L38 15L38

Cleanable polyurethane frame type filter.

HIGH ALTITUDE

Input −1

High Altitude

High Altitude Pressure

Switch Kit

LPG/Propane Kit

through

−14

Orifice Kit

Natural Gas Only

4501−7500 ft.

(1373 − 2286m)

7501−10,000 ft. (2287 − 3048m)

0−7500 ft.

(0 − 2286m)

7501−10,000 ft. (2287 − 3048m)

−044

−070

59M16 no change no change 45L60 47M81

−090 59M16 15M22 56L32 45L60 47M81

−110 59M16 15M22 56L32 45L60 47M81

−135 59M16 49L90 15M22 45L60 47M81

Input −15

High Altitude

High Altitude Pressure

Switch Kit

LPG/Propane Kit

Input −15

and later

Orifice Kit

Natural Gas Only

4501−7500 ft.

(1373 − 2286m)

7501−10,000 ft. (2287 − 3048m)

0−7500 ft.

(0 − 2286m)

7501−10,000 ft. (2287 − 3048m)

−045

−070

59M17 no change no change 25W20 25W21

−090 59M17 15M22 56L32 45L60 25W21

−110 59M17 15M22 56L32 25W20 25W21

−135 59M17 49L90 15M22 25W20 25W21

Required for proper operation at altitudes from 7501 to 10,000 ft.

NOTE − G40DF(X) units do NOT require a manifold change due to elevation. Manifold pressureremains the same at all elevations.

BLOWER DATA

G40DF−24A−045 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts

0.00 0 1202 565 417 1058 500 367 828 390 278

0.05 12 1185 560 410 1041 490 360 819 385 274

0.10 25 1167 550 402 1024 482 353 809 380 270

0.15 37 1147 540 396 1008 475 346 793 375 265

0.20 50 1127 530 390 991 470 338 776 365 260

0.25 62 1104 520 382 979 460 335 764 360 257

0.30 75 1081 510 374 966 455 331 752 355 254

0.40 100 1018 480 357 922 435 319 712 335 244

0.50 125 960 455 342 873 410 306 651 305 234

0.60 150 901 425 330 811 385 290 618 290 231

0.70 175 815 385 313 691 325 272 564 265 221

0.80 200 685 325 289 619 290 259 465 220 203

0.90 225 558 265 271 510 240 238 395 185 190

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

Page 4

BLOWER DATA Cont.

G40DF−36A−070 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0.00 0 1475 695 616 1343 635 554 1151 545 495 989 465 415

0.05 12 1449 685 606 1321 625 543 1139 540 481 983 465 407

0.10 25 1423 670 595 1298 615 532 1127 530 466 976 460 398

0.15 37 1397 660 585 1276 600 521 1115 525 452 970 460 390

0.20 50 1371 645 574 1253 590 510 1103 520 437 963 455 381

0.25 62 1345 635 563 1228 580 494 1090 515 428 953 450 371

0.30 75 1318 620 552 1203 570 478 1077 510 418 943 445 360

0.40 100 1249 590 528 1151 545 455 1039 490 395 918 435 346

0.50 125 1200 565 508 1094 515 432 998 470 374 882 415 331

0.60 150 1112 525 475 1033 490 409 951 450 354 831 390 313

0.70 175 1032 485 455 968 455 390 856 405 338 722 340 280

0.80 200 959 455 434 876 415 359 737 350 299 666 315 266

0.90 225 770 365 389 715 335 321 667 315 278 591 280 244

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

G40DF−36B−090 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0.00 0 1598 755 608 1408 665 526 1166 550 436 963 455 355

0.05 12 1579 745 599 1398 660 518 1164 550 428 966 455 351

0.10 25 1559 735 589 1388 655 509 1161 550 420 968 455 346

0.15 37 1528 720 573 1369 645 497 1156 545 413 966 455 341

0.20 50 1497 705 556 1350 635 485 1150 545 406 964 455 335

0.25 62 1465 690 544 1326 625 473 1137 535 398 955 450 329

0.30 75 1432 675 532 1301 615 460 1124 530 389 945 445 323

0.40 100 1370 645 509 1248 590 438 1093 515 373 933 440 313

0.50 125 1294 610 482 1198 565 420 1055 500 355 902 425 302

0.60 150 1213 575 456 1141 540 397 1012 480 343 862 405 285

0.70 175 1139 540 437 1054 495 371 917 435 313 802 380 272

0.80 200 1002 475 401 948 445 342 850 400 295 728 345 251

0.90 225 901 425 374 822 390 313 740 350 272 − − − − − − − − −

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

Page 5

BLOWER DATA Cont.

G40DF−36C−110 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0.00 0 1660 785 668 1425 675 589 1205 570 489 1015 480 409

0.05 12 1635 770 652 1415 670 575 1205 570 480 1010 475 405

0.10 25 1610 760 636 1405 665 560 1205 570 471 1010 475 402

0.15 37 1575 745 617 1395 660 544 1200 565 460 1005 475 395

0.20 50 1535 725 597 1380 650 524 1200 565 449 1005 475 387

0.25 62 1490 705 576 1350 635 506 1190 560 436 1000 470 380

0.30 75 1450 685 556 1320 625 488 1175 555 422 1000 470 372

0.40 100 1350 635 516 1250 590 456 1125 530 400 970 460 347

0.50 125 1230 580 472 1150 545 416 1045 495 365 910 430 319

0.60 150 1110 525 438 1025 485 374 950 450 329 820 385 284

0.70 175 950 450 396 870 410 329 800 380 286 695 330 251

0.80 200 800 380 362 715 390 294 675 320 245 − − − − − − − − −

0.90 225 685 325 300 625 295 237 560 265 208 − − − − − − − − −

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

G40DF−48C−090 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0.00 0 2039 960 749 1852 875 657 1595 755 562 1325 625 466

0.05 12 1998 945 727 1826 860 638 1576 745 547 1338 632 460

0.10 25 1956 925 704 1800 850 619 1556 735 532 1351 640 453

0.15 37 1921 905 692 1770 835 602 1541 725 518 1340 630 441

0.20 50 1885 890 679 1739 820 585 1526 720 503 1329 625 428

0.25 62 1844 870 662 1701 805 568 1502 710 488 1301 615 414

0.30 75 1802 850 645 1663 785 551 1477 695 473 1272 600 399

0.40 100 1693 800 606 1583 745 517 1415 670 448 1226 580 378

0.50 125 1600 755 570 1491 705 485 1334 630 414 1170 550 360

0.60 150 1494 705 540 1406 665 457 1248 590 389 1110 525 337

0.70 175 1378 650 509 1300 615 426 1166 550 367 1026 485 316

0.80 200 1248 590 478 1161 550 390 1027 485 331 − − − − − − − − −

0.90 225 1097 520 439 1028 485 360 925 435 307 − − − − − − − − −

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

G40DF−48C−110 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0.00 0 2034 960 846 1790 845 712 1508 710 595 1226 580 477

0.05 12 2001 945 825 1761 830 694 1493 705 581 1224 580 470

0.10 25 1968 930 803 1731 815 675 1477 695 567 1222 575 463

0.15 37 1924 910 781 1708 805 657 1470 695 555 1219 575 455

0.20 50 1879 885 758 1685 795 638 1463 690 542 1216 575 447

0.25 62 1837 865 736 1654 780 618 1442 680 528 1201 565 437

0.30 75 1794 845 714 1623 765 597 1420 670 514 1186 560 427

0.40 100 1681 795 669 1548 730 564 1361 640 483 1134 535 400

0.50 125 1622 765 630 1445 680 524 1280 605 447 1065 505 371

0.60 150 1447 685 592 1312 620 479 1165 550 404 1000 470 343

0.70 175 1289 610 545 1178 555 434 1056 500 369 907 430 319

0.80 200 1157 545 502 1067 505 406 956 450 348 816 385 296

0.90 225 1012 480 472 931 440 372 840 395 320 690 325 265

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

Page 6

BLOWER DATA Cont.

5 ton units with 3/4 hp

G40DF−60C−110 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

.00 0 2450 1155 1170 2355 1110 1005 2145 1015 840 1845 870 705

.05 10 2430 1150 1165 2340 1105 995 2130 1005 835 1840 870 695

.10 25 2380 1120 1145 2315 1090 985 2105 995 825 1830 865 690

.15 35 2350 1110 1135 2260 1065 965 2085 985 815 1815 855 680

.20 50 2300 1085 1115 2235 1055 955 2060 975 805 1805 850 675

.25 60 2270 1070 1105 2205 1040 945 2015 950 785 1780 840 665

.30 75 2245 1060 1100 2150 1015 925 1995 940 775 1770 835 655

.40 100 2135 1010 1060 2070 975 895 1925 910 750 1730 815 640

.50 125 2055 970 1035 1990 940 870 1855 875 725 1695 800 625

.60 150 1975 930 1010 1910 900 845 1785 845 705 1650 775 605

.70 175 1870 880 980 1830 865 820 1695 800 680 1575 745 585

.80 200 1760 830 950 1720 815 795 1605 755 655 1505 710 570

.90 225 1625 765 915 1560 735 755 1515 715 640 1435 675 555

G40DF−60D−135 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

0.00 0 2845 1345 1143 2692 1270 961 2451 1155 818 2054 970 686

0.05 12 2774 1310 1128 2628 1240 948 2354 1110 809 2022 955 680

0.10 25 2702 1275 1112 2564 1210 935 2256 1065 799 1989 940 674

0.15 37 2629 1240 1095 2494 1175 918 2203 1040 784 1933 910 666

0.20 50 2556 1205 1077 2424 1145 901 2150 1015 769 1877 885 657

0.25 62 2471 1165 1061 2309 1090 890 2089 985 759 1835 865 649

0.30 75 2385 1125 1045 2194 1035 878 2028 955 749 1792 845 640

0.40 100 2184 1030 1022 2066 975 851 1900 895 727 1697 800 626

0.50 125 2019 955 990 1917 905 830 1779 840 707 1584 750 602

0.60 150 1865 880 957 1760 830 796 1630 770 676 1491 705 583

0.70 175 1697 800 927 1592 750 768 1475 695 656 1364 645 557

0.80 200 1513 715 897 1485 700 740 1378 650 627 1266 600 538

0.90 225 1385 655 863 1305 615 712 1206 570 598 1120 530 516

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

Page 7

BLOWER DATA Cont.

5 ton units with 1 hp

G40DF−60C−110 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

.00 0 2475 1170 1276 2280 1075 987 1995 940 845 1690 795 698 .10 25 2390 1125 1248 2235 1055 955 1990 940 829 1675 790 690 .20 50 2330 1100 1223 2180 1030 945 1975 930 809 1665 785 675 .30 75 2245 1060 1192 2125 1000 911 1940 915 786 1660 785 657 .40 100 2175 1025 1187 2050 965 880 1895 895 757 1650 780 636 .50 125 2085 985 1145 1970 930 849 1835 870 734 1625 765 619 .60 150 2020 955 1129 1880 885 815 1750 825 695 1580 745 599 .70 175 1920 905 1094 1775 835 785 1660 785 669 1525 720 579 .80 200 1785 840 1052 1685 795 762 1585 745 645 1440 680 556 .90 225 1670 790 1020 1600 755 741 1520 715 633 1370 645 538

G40DF−60D−135 PERFORMANCE

External Static

Air Volume / Watts at Different Blower Speeds

External Static

Pressure

High Medium−High Medium−Low Low

in. w.g. Pa cfm L/s Watts cfm L/s Watts cfm L/s Watts cfm L/s Watts

.00 0 2660 1255 1379 2325 1095 1059 1960 925 864 1655 780 684 .10 25 2560 1210 1353 2310 1090 1030 1945 915 840 1640 775 667 .20 50 2490 1175 1325 2280 1075 1000 1940 915 824 1630 770 661 .30 75 2415 1140 1293 2225 1050 972 1930 910 801 1625 765 649 .40 100 2345 1105 1264 2170 1025 941 1910 900 779 1620 760 638 .50 125 2265 1070 1235 2115 1000 918 1870 880 754 1615 760 624 .60 150 2165 1020 1199 2020 955 880 1830 865 733 1585 745 604 .70 175 2050 965 1160 1940 915 854 1755 830 705 1570 740 604 .80 200 1955 920 1112 1865 880 828 1680 790 683 1515 715 584 .90 225 1865 880 1096 1760 830 797 1605 755 656 1465 690 567

NOTE − All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished − field provided) in place. Also see Filter Air Resistance table.

FILTER AIR RESISTANCE

cfm L/s in. w.g. Pa cfm L/s in. w.g. Pa

0 0 0.00 0 1400 660 0.15 35 200 95 0.01 0 1600 755 0.19 45 400 190 0.03 5 1800 850 0.23 55 600 285 0.04 10 2000 945 0.27 65 800 380 0.06 15 2200 1040 0.33 80

1000 470 0.09 20 2400 1130 0.38 95 1200 565 0.12 30 2600 1225 0.44 11 0

 Data is for 1 inch (25 mm) cleanable filter (field provided).

Page 8

G40DF(X) PARTS ARRANGEMENT

FIGURE 1

Blower Assembly

Blower Motor

Capacitor

Internal Flue Pipe

Assembly

Flue Box Gasket

Flue Collector Box

Gasket

Combustion Air Inducer

Gasket

Manifold

Burner

Gas Valve

Flame Rollout

Switches

Flame

Sensor

Primary

Limit

Ignitor

Heat Exchanger

Ignitor

Bracket

Combustion Air

Pressure Switch

Combustion

Air Orifice

Gas

Orifices

Flue

Chase

Gasket

Limit Sheild with

−3 Units only

Ignition Control

Transformer

DoorInterlock Switch

Pressure Port

Location for

−1 to −14 units

Page 9

I−UNIT COMPONENTS

G40DF(X) unit components are shown in figure 1. The gas valve, combustion air inducer and burners can be accessed by removing the burner access panel. Electrical components are in the control box (figure 2) found in the blower section.

CAUTION

Electrostatic discharge can affect electronic components. Take precautions during furnace installation and service to protect the furnace’s electronic controls. Precautions will help to avoid control exposure to electrostatic discharge by putting the furnace, the control and the technician at the same electrostatic potential. Neutralize electrostatic charge by touching hand and all tools on an unpainted unit surface, such as the gas valve or blower deck, before performing any service procedure.

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

1. Control Transformer (T1)

A transformer located in the control box provides power to the low voltage section of the unit. Transformers on all models are rated 40VA with a 120V primary and a 24V secondary.

2.Door Interlock Switch (S51)

A door interlock switch rated 14A at 125VAC is wired in series with line voltage. When the blower door is removed the unit will shut down.

FIGURE 2

CONTROL BOX

G40UH(X)

SureLight Control

Transformer

DoorInterlock Switch

WARNING

Shock hazard. Disconnect power before servicing. Control is

not field repairable. If control is inoperable, simply replace entire control.

Can cause injury or death. Unsafe operation will result if repair is attempted.

3. SureLight Ignition Control (A92) Figure 3 Control 56L84, 10M93 & 32M88

The Lennox SureLight ignition system consists of ignition

control board, ignitor and sensor. The board and ignitor

work in combination to ensure furnace ignition and ignitor

durability. The SureLight integrated board controls all ma-

jor furnace operations. The board also features two LED

lights (DS1, DS2) for troubleshooting and two accessory

terminals rated at (1) one amp. Table 1 gives control termi-

nal designations. Tables 2 and 3 show jack plug terminal

designations. See table 11 for troubleshooting diagnostic

codes. Units equipped with the SureLight board can be

used with either electronic or electro−mechanical thermo-

stats without modification. The SureLight ignitor is made

of durable silicon−nitride. Ignitor longevity is also en-

hanced by voltage ramping by the control board. The

board finds the lowest ignitor temperature which will suc-

cessfully light the burner, thus increasing the life of the ig-

nitor.

TABLE 1

PARK

TERMINAL DESIGNATIONS

COOL−H HEAT−H EAC−H HUM−H XFMR−H LINE−H LINE−N HUM−N EAC−N XFMR−N CIR−N

Blower − Cooling Speed (120VAC) Blower − Heating Speed (120VAC) Electronic Air Cleaner (120VAC) Humidifier (120VAC) Transformer (120VAC) Input (120VAC) Input (Neutral) Humidifier (Neutral) Electronic Air Cleaner (Neutral) Transformer (Neutral) Blower − Neutral

(FLAME SENSE)

Alternate Blower Speeds (Dead)

Flame Sensor

120V HOT

120V NEUT

Page 10

SURELIGHT INTEGRATED CONTROL BOARD

FIGURE 3

J156

FLAME SENSE

J58

XFMR−N

TABLE 2

SureLight BOARD J156 (J2) TERMINAL

DESIGNATIONS

PIN # FUNCTION

1 Combustion Air Inducer Line

Ignitor Line

Combustion Air Inducer Neutral

Ignitor Neutral

TABLE 3

SureLight BOARD J58 (J1) TERMINAL

DESIGNATIONS

PIN # FUNCTION

1 Secondary Limit

Not Used

24V

Not Used

Rollout Switch In

24V

Primary Limit

Ground

Gas Valve In

Pressure Switch Out

Rollout Switch Out

Gas Valve Out

a−Electronic Ignition (See Figure 8)

On a call for heat the SureLight control monitors the combustion air inducer prove switch. The control will not begin the heating cycle if the prove switch is closed (by−passed). Once the proving switch is determined to be open, the combustion air inducer is energized. When the differential in the prove switch is great enough, the prove switch closes and a 15−second pre−purge begins. If the prove switch is not proven within 2−1/2 minutes, the control goes into Watchguard−Pressure Switch mode for a 5−minute re−set period. After the 15−second pre−purge period, the SureLight ignitor warms up for 20 seconds during which the gas valve opens at 19 seconds for a 4−second trial for ignition. Control 10M93 and 32M88 energizes the ignitor during the trial until flame is sensed. Control 56L84 energizes the ignitor for 1 second only. If ignition is not proved during the 4−second period, the control will try four more times with an inter purge and warm−up time between trials of 35 seconds. After a total of five trials for ignition (including the initial trial), the control goes into Watchguard−Flame Failure mode. After a 60−minute reset period, the control will begin the ignition sequence again. The SureLight control board has an added feature that prolongs the life of the ignitor. After a successful ignition, the SureLight control utilizes less power to energize the ignitor on successive calls for heat. The control continues to ramp down the voltage to the ignitor until it finds the lowest amount of power that will provide a successful ignition. This amount of power is used for 255 cycles. On the 256th call for heat, the control will again ramp down until the lowest power is determined and the cycle begins again.

b−Fan Time Control

The fan on time of 45 seconds is not adjustable. Fan off time (time that the blower operates after the heat demand has been satisfied) can be adjusted by flipping the dip switches located on the SureLight integrated control. The unit is shipped with a factory fan off setting of 90 seconds. For customized comfort, monitor the supply air temperature once the heat demand is satisfied. Note the supply air temperature at the instant the blower is de−energized. Adjust the fan−off delay to achieve a supply air temperature between 90° − 110° at the instant the blower is de−energized. (Longer delay times allow for lower air temperature, shorter delay times allow for higher air temperature). See figure 4.

FIGURE 4

FAN-OFF TIME ADJUSTMENT

To adjust fan−off timing, flip dip switch to desired setting.

60sec. 90sec. 120sec. 180sec.

Page 11

WARNING

Shock hazard. Disconnect power before servicing. Control is

not field repairable. If control is inoperable, simply replace entire control.

Can cause injury or death. Unsafe operation will result if repair is attempted.

4. SureLight Ignition Control (A92) Figure 5 Control 69M08

The Lennox SureLight ignition system consists of ignition

control board, ignitor and sensor. The board and ignitor

work in combination to ensure furnace ignition and ignitor

durability. The SureLight integrated board controls all ma-

jor furnace operations. The board also features two LED

lights (DS1 red and DS2 green) for troubleshooting and

two 120 volt accessory terminals, each rated at (1) one

amp. The board also features a 3 amp fuse for low voltage

overcurrent protection. Table 4 gives control terminal des-

ignations. Tables 5 and 6 show jack plug terminal designa-

tions. See table 11 for troubleshooting diagnostic codes.

Units equipped with the SureLight board can be used with

either electronic or electro−mechanical thermostats with-

out modification. The SureLight ignitor is made of durable

silicon−nitride. Ignitor longevity is also enhanced by volt-

age ramping by the control board. The board finds the low-

est ignitor temperature which will successfully light the

burner, thus increasing the life of the ignitor.

TABLE 4

SURELIGHT BOARD TERMINAL DESIGNATIONS

COOL Blower − Cooling Speed (120V)

HEAT Blower − Heating Speed (120V)

PARK

Unused Blower Lead (not energized)

FAN

Continuous Low Blower Speed

EAC

Accessory Terminal (120V)

XFMR

Transformer (120V)

LINE

Input (120V)

HUM

Heat Only Accessory (120V)

5 Terminals

120V Neutral

Flamer Sensor

SURELIGHT INTEGRATED CONTROL BOARD

FIGURE 5

3 AMP, 32 VAC FUSE

TABLE 5

SURELIGHT BOARD 4 PIN DESIGNATIONS

PIN # FUNCTION

1 Combustion Air Inducer Line

Ignitor Line

Combustion Air Inducer Neutral

Ignitor Neutral

TABLE 6

SURELIGHT BOARD 12 PIN DESIGNATIONS

PIN # FUNCTION

1 Prove Switch and Limit Out

Not Used

24V Hot

Not Used

Rollout Switch In 1

24V Common

Limit In

Ground

Gas Valve Common

Prove Switch In

Rollout Switch Out 2

Gas Valve Hot

Page 12

c−Electronic Ignition (See Figure 8)

On a call for heat the SureLight control monitors the combustion air inducer prove switch. The control will not begin the heating cycle if the prove switch is closed (by−passed). Once the proving switch is determined to be open, the combustion air inducer is energized. When the differential in the prove switch is great enough, the prove switch closes and a 15−second pre−purge begins. If the prove switch is not proven within 2−1/2 minutes, the control goes into Watchguard−Pressure Switch mode for a 5−minute re−set period. After the 15−second pre−purge period, the SureLight ignitor warms up for 20 seconds during which the gas valve opens at 19 seconds for a 4−second trial for ignition. The ignitor stays energized during the trial until flame is sensed. If ignition is not proved during the 4−second period, the control will try four more times with an inter purge and warm−up time between trials of 35 seconds. After a total of five trials for ignition (including the initial trial), the control goes into Watchguard−Flame Failure mode. After a 60−minute reset period, the control will begin the ignition sequence again. The SureLight control board has an added feature that prolongs the life of the ignitor. After a successful ignition, the SureLight control utilizes less power to energize the ignitor on successive calls for heat. The control continues to ramp down the voltage to the ignitor until it finds the lowest amount of power that will provide a successful ignition. This amount of power is used for 255 cycles. On the 256th call for heat, the control will again ramp down until the lowest power is determined and the cycle begins again.

d−Heating Fan Delay Time

The heating fan on time of 45 seconds is not adjustable. Fan off time (time that the blower operates after the heat demand has been satisfied) can be adjusted by setting the S1 dip switches located on the SureLight integrated control. The unit is shipped with a factory fan off setting of 90 seconds. Fan off time will affect comfort and is adjustable to satisfy individual applications. For customized comfort, monitor the supply air temperature once the heat demand is satisfied. Note the supply air temperature at the instant the blower is de−energized. Adjust the fan−off delay to achieve a supply air temperature between 90° − 110° at the instant the blower is de−energized. (Longer delay times allow for lower air temperature, shorter delay times allow for higher air temperature). See table 7 for switch settings and fan delay times.

e−Cooling Fan Delay Time

The cooling fan on time is fixed at 2 seconds and cannot be adjusted. G40DF units do not have a cooling fan off delay time.

TABLE 7

S1 DIP SWITCH SETTINGS

Heat Off Delay

Switch 1 Switch 2 Seconds

OFF OFF 60

OFF ON 90

ON OFF 120

ON ON 180

5. Ignition Control (A92) Figure 6 Control 78M47 & 100973−01

WARNING

Shock hazard. Disconnect power before servicing. Control is

not field repairable. If control is inoperable, simply replace entire control.

Can cause injury or death. Unsafe operation will result if repair is attempted.

The hot surface ignition system consist of an integrated control board (figure 6 with control terminal designations in table 10), sensor (figure 9) and ignitor (figure 10). The control board and ignitor work in combination to ensure furnace ignition and ignitor durability. The control board controls all major furnace operations. The control board also features two LED lights (AN1 red and AN2 green) for troubleshooting and two accessory terminals rated at (1) one amp. The control board also features a (3) amp fuse for overcurrent protection. Tables 8 and 9 show jack plug terminal designations. See table 11 for troubleshooting diagnostic codes. The mini−nitride ignitor is made from a non− porous, high strength proprietary ceramic material that provides long life and trouble free maintenance. The control board continuously monitors line voltage and maintains the ignitor power at a consistent level to provide proper lighting and maximum ignitor life.

Page 13

INTEGRATED CONTROL BOARD

FIGURE 6

AN2

GREEN

AN1 RED

TABLE 8

4−Pin Terminal Designation

PIN # FUNCTION

1 Combustion Air Inducer Line

Ignitor Line

Combustion Air Inducer Neutral

Ignitor Neutral

TABLE 9

12−Pin Terminal Designations

PIN # FUNCTION

1 High Limit Output

2 Not Used

3 24V Line

4 Not Used

5 Rollout Switch Out

6 24V Neutral

7 High Limit Input

8 Ground

9 Gas Valve Common

10 Prove Switch In

11 Rollout Switch In

12 Gas Valve Out

TABLE 10

TERMINAL DESIGNATIONS

120 Volt Hot

COOL Cool Speed

HEAT Heat Speed

PARK Park

EAC Electrconic Air Cleaner

XFMR Transformer

LINE Line

HUM Humidifier

120 Volt Neutral

CIRC Blower

XMFR Transformer

HUM Humidifier

LINE Line

Flame FS Flame Signal

Electronic Ignition (See Figure 8)

On a call for heat the ignition board monitors the combustion air inducer prove switch. The control board will not begin the heating cycle if the prove switch is closed (by− passed). Once the prove switch is determined to be open, the combustion air inducer is energized. When the differential in the prove switch is great enough, the prove switch closes and a 15−second pre−purge begins. If the prove switch is not proven within 2−1/2 minutes, the control board goes into Watchguard−Pressure Switch mode for a 5−minute re−set period. After the 15−second pre−purge period, the ignitor warms up for 20 seconds during which the gas valve opens at 19 seconds for a 4−second trial for ignition. The ignitor remains energized for the first 3 seconds during the 4 second trial. If ignition is not proved during the 4−second period, the control will try four more times with an inter purge and warm−up time between trials of 35 seconds. After a total of five trials for ignition (including the initial trial), the control goes into Watchguard−Flame Failure mode. After a 60−minute reset period, the control will begin the ignition sequence again. The control board has an added feature of ignitor power regulation to maintain consistent lighting and longer ignitor life under all line voltage conditions.

Fan Time Control

The fan on time of 45 seconds is not adjustable. Fan off time (time that the blower operates after the heat demand has been satisfied) can be adjusted by moving the jumper to a different setting. The unit is shipped with a factory fan off setting of 90 seconds. For customized comfort, monitor the supply air temperature once the heat demand is satisfied. Note the supply air temperature at the instant the blower is de−energized. Adjust the fan−off delay to achieve a supply air temperature

Page 14

between 90° − 110° at the instant the blower is de−energized. (Longer delay times allow for lower air temperature, shorter delay times allow for higher air temperature). See figure 7. Board 100973−0 only has a 45 second fan off delay after cooling demand is satisfied. This delay timing is factory set and non adjustable.

The ignition control boards are equipped with two LED lights for troubleshooting. The diagnostic codes are listed in table 11.

FAN-OFF TIME ADJUSTMENT

To adjust fan−off timing, reposition jumper across pins to

achieve desired setting.

FIGURE 7

TABLE 11

DIAGNOSTIC CODES

Make sure to Identify LED’S Correctly.

Refer to figures 3 and 5 for control board layout.

LED #1

DS #1 AN #1

LED #2

DS #2 AN #2

DESCRIPTION

SIMULTANEOUS

SLOW FLASH

SIMULTANEOUS

SLOW FLASH

Power on − Normal operation. Also signaled during cooling and continuous fan.

SIMULTANEOUS

FAST FLASH

SIMULTANEOUS

FAST FLASH

Normal operation − signaled when heating demand initiated at thermostat.

SLOW FLASH ON

Primary or secondary limit switch open. Limit must close within 3 minutes or unit goes into 1 hour Watchguard.

OFF SLOW FLASH

Prove switch open. OR: Blocked inlet/exhaust vent; OR: Prove switch closed prior to activation of combustion air inducer.

ALTERNATING

SLOW FLASH

ALTERNATING

SLOW FLASH

Watchguard −− burners failed to ignite.

SLOW FLASH OFF Flame sensed without gas valve energized.

ON SLOW FLASH Rollout switch open. OR: 24V pin connector improperly attached.

ON ON

ON OFF

Circuit board failure or control wired incorrectly.

OFF ON

FAST FLASH SLOW FLASH Main power polarity reversed. Switch line and neutral.

SLOW FLASH FAST FLASH Low flame signal. See Table 18 for flame sense.

ALTERNATING

FAST FLASH

ALTERNATING

FAST FLASH

The following conditions are sensed Improper main ground (Control 56L84, 10M93, 32M88, 69M08) during ignitor warm up period ONLY, improper main ground continuously (Control 78M47) OR: Broken ignitor (Control 56L84, 10M93, 32M88, 69M08) OR: Open ignitor circuit (Control 56L84, 10M93, 32M88, 69M08) OR: Line voltage below 75V (Control 56L84, 10M93, 32M88, 69M08)

90V (Control 78M47 & 100973−01)

NOTE − Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second).

FIGURE 8

DEMAND

CAI

GAS VALVE

OFF

IGNITOR*

15 Sec.

Pre −Purge

20 sec.

Ignitor Warm−up

*4 Sec.Trial

for Ignition

Post

Purge

5 SEC

Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on OFF TIME" Setting.

INDOOR BLOWER

Blower On"

Delay

End of

Heat Demand

Blower

Off

Time

* Control 78M47 & 100973−01 will energize ignitor the first 3 seconds of the 4 second trial

56L84, 1 second, 32M88, 69M08 entire trial (4 sec)

Page 15

6.Flame Sensor (Figure 9)

A flame sensor is located on the left side of the burner support. See parts arrangement figure1. The sensor is mounted on the flame rollout plate and the tip protrudes into the flame envelope of the left−most burner. The sensor can be removed for service without removing any part of the burners. During operation, flame is sensed by current passed through the flame and sensing electrode. The ignition control allows the gas valve to remain open as long as flame signal is sensed. See table 18 for flame sense signal.

FIGURE 9

5/16"

7. Ignitor (Figure 10)

Two type ignitors are used for the SureLight ignition system; silicon nitride and mini nitride. The ignition control finds the lowest ignitor temperature which will successfully light the burner, thus increasing the life of the ignitor. Due to this feature of the board, voltage cannot be measured. To check ignitor, measure its resistance. See table 12 for ohm value and ignitor control matchup.

TABLE 12

SureLight Control

Ignitor Resistance

56L84, 10M93, 32M88, 69M08

Silicon Nitride 10.9 − 19.7

78M47 & 100973−01

Mini Nitride 50 − 450

NOTE − The G40DF(X) furnace contains electronic components that are polarity sensitive. Make sure that the furnace is wired correctly and is properly grounded.

8.Blower Motors and Capacitors

All G40DF(X) units use direct drive blower motors. All motors are 120V permanent split capacitor motors to ensure maximum efficiency. Ratings for capacitors will be on motor nameplate.

NOTE − Shafts on 1 HP motors have 2 flat sides and are matched with blower wheels with 2 set screws.

FIGURE 10

B"

Ignitor Location

BURNERS FRONT VIEW

MEASUREMENT IS TO I.D. OF RETENTION RING

BRACKET

Silicon nitride

Mini Nitride

A" B"

.625 .406

.685 .306

A"

IGNITOR TYPE

9.Flame Rollout Switches (S47)

Flame rollout switch is a high temperature limit located on top of the burner box. See parts arrangement figure 1. Each furnace is equipped with two identical switches. One switch is located over the leftmost burner and the other switch is located over the rightmost burner. The limit is a N.C. SPST manual-reset limit connected in series with the ignition control A92. When S47 senses rollout, the ignition control immediately stops ignition and closes the gas valve. If unit is running and flame rollout is detected, the gas valve will close and ignition control will be disabled. Rollout can be caused by a blocked heat exchanger, flue or lack of combustion air. The switch is factory set to open at 210° F and cannot be adjusted. The switch can be manually reset. To manually reset a tripped switch, push the reset button located on the control.

10.Primary Limit Control (S10)

The primary limit (S10) on G40DF(X) units is located in the heating vestibule panel. G40DF−3 and later models will have a limit shield. See figure 11 and make note of limit orientation to shield. When excess heat is sensed in the heat exchanger, the limit will open. If the limit is open, the furnace control energizes the supply air blower and closes the gas valve. The limit automatically resets when unit temperature returns to normal. The switch must reset within three minutes or SureLight board will go into Watch guard for one hour. The setpoint is factory set (printed on side of switch) and cannot be adjusted.

Page 16

FIGURE 11

G40DF−1, −2 UNITS

WITHOUT SHIELD

G40DF UNITS WITH SHIELD

11.Secondary Limit Controls (S21)

The secondary limit (S21) is an air stream type limit located in the blower compartment in the back side of the blower housing. See figure 12. When excess heat is sensed in the blower compartment, the limit will open. If the limit is open, the furnace control energizes the supply air blower and closes the gas valve. The limit automatically resets when unit temperature returns to normal. G40DF−1 through −6 units use a 3/4" diameter limit factory set to open at 150°. G40DF−7 and later units, use a 1/2" diameter limit factory set to open at 135 °.

FIGURE 12

SUPPLY AIR BLOWER AND SECONDARY LIMIT

SECONDARY

LIMIT

CAPACITOR

MOTOR/BLOWER

ASSEMBLY

To Remove Blower From Unit: Disconnect Power, Remove Control

Box, Remove flue pipe, Remove Bolts and Unplug Motor Wires

From Control Board. Then Slide Out Front of Unit.

12.Gas Valve Figures 13, 14, 15 & 16

The G40DF(X) uses a gas valve manufactured by Honeywell or White Rodgers. The valve is internally redundant to assure safety shut−off. If the gas valve must be replaced, the same type valve must be used.

24VAC terminals and gas control knob or switch are located on the valve. All terminals on the gas valve are connected to wires from the electronic ignition control. 24V applied to the terminals energizes the valve.

Inlet and outlet pressure taps are located on the valve. A regulator adjustment screw is located on the valve.

LPG changeover kits are available from Lennox. Kits include burner orifices and a gas valve regulator conversion kit.

WHITE RODGERS 36E SERIES GAS VALVE

GAS VALVE SHOWN IN OFF POSITION

MANIFOLD

PRESSURE

ADJUSTMENT

SCREW

MANIFOLD

PRESSURE

OUTLET

FIGURE 13

FIGURE 14

WHITE RODGERS 36F Series Gas Valve

GAS VALVE SHOWN IN OFF POSITION

MANIFOLD

PRESSURE

ADJUSTMENT

SCREW

MANIFOLD

PRESSURE

OUTLET

OFF

HONEYWELL VR8205 SERIES GAS VALVE

GAS VALVE SHOWN IN OFF POSITION

MANIFOLD PRESSURE

ADJUSTMENT

SCREW

MANIFOLD

PRESSURE

OUTLET

FIGURE 15

HONEYWELL VR8205 SERIES GAS VALVE

(With On/Off Switch)

GAS VALVE ON/OFF SWITCH SHOWN IN ON POSITION

MANIFOLD

PRESSURE

OUTLET

MANIFOLD

PRESSURE

ADJUSTMENT

SCREW

(under cap)

FIGURE 16

Page 17

13.Combustion Air Inducer (B6)

All G40DF(X) units use a combustion air inducer to move air through the burners and heat exchanger during heating operation. The blower uses a 120VAC motor. The motor operates during all heating operation and is controlled by furnace control A92. The inducer also operates for 15 seconds before burner ignition (pre-purge) and for 5 seconds after the gas valve closes (post-purge).

A proving switch connected to the combustion air inducer orifice plate (figure 17) is used to prove inducer operation. The combustion air inducer orifice will be different for each model. See table 13 for orifice sizes. The switch monitors air pressure in the inducer housing. During normal operation, the pressure in the housing is negative. If pressure becomes less negative (signifying an obstruction) the proving switch opens. When the proving switch opens, the furnace control (A92) immediately closes the gas valve to prevent burner operation.

TABLE 13

G40DF(X) Unit

C.A.I. Orifice Size

−045 1.438"

−070 1.688"

−090 1.875"

−110 2.250"

−135 2.600"

FIGURE 17

Flue Box Gasket

Flue Collector Box

Gasket

Combustion Air Inducer

Combustion Air

Orifice Plate

COMBUSTION AIR INDUCER ASSEMBLY

Prove Switch

−1 to −14

pressure

port location

Pressure Port

14.Combustion Air Inducer Proving Switch (S18)

G40DF(X) series units are equipped with a combustion air

proving switch located on the combustion air inducer orifice

bracket. The switch is connected to the combustion air in-

ducer housing by means of a flexible silicone hose. It moni-

tors negative air pressure in the combustion air inducer

housing.

The switch is a single-pole single-throw proving switch elec-

trically connected to the furnace control. The purpose of the

switch is to prevent burner operation if the combustion air in-

ducer is not operating or if the flue becomes obstructed.

On start-up, the switch senses that the combustion air inducer is operating. It closes a circuit to the furnace control when pressure inside the combustion air inducer decreases to a certain set point. Set points vary depending on unit size. See table 14. The pressure sensed by the switch is negative relative to atmospheric pressure. If the flue becomes obstructed during operation, the switch senses a loss of negative pressure (pressure becomes more equal with atmospheric pressure) and opens the circuit to the furnace control and gas valve. A bleed port on the switch allows relatively dry air in the vestibule to purge switch tubing, to prevent condensate build up. The switch is factory set and is not field adjustable. It is a safety shut-down control in the furnace and must not be by− passed for any reason. If switch is closed or by−passed, the control will not initiate ignition at start up.

TABLE 14

PROVE SWITCH SET POINTS

Unit

0 − 4500’

(0 − 1372m)

4501’ − 7500’

(1373 −

2286m)

7501’ − 10000’ (2286 −

3098m)

−045−1 to −14 .36" (89Pa) .36" (89Pa) .36" (89Pa)

−070−1 to −14 .36" (89Pa) .36" (89Pa) .36" (89Pa)

−090−1 to −14 .47" (116Pa) .43" (106Pa) .36" (89Pa)

−110−1 to −14 .51" (126Pa) .43" (106Pa) .36" (89Pa)

−135−1 to −14 .51" (126Pa) .47" (116Pa) .43" (106Pa)

ALL −15 and later

models

.0.31" (77Pa)

NOTE−Some units require a high altitude pressure

switch kit if installed above 4500 ft (1370 m).

Page 18

II−PLACEMENT AND INSTALLATION

Make sure unit is installed in accordance with installation instructions and applicable codes.

III−START-UP A−Preliminary and Seasonal Checks

1 − Inspect electrical wiring, both field and factory installed

for loose connections. Tighten as required.

2 − Check voltage at disconnect switch. Voltage must be

within range listed on the nameplate. If not, consult the power company and have voltage condition corrected before starting unit.

B−Heating Start-Up

WARNING

Shock and burn hazard.

G40DF(X) units are equipped with a hot surface ignition system. Do not attempt to light manually.

1 − STOP! Read the safety information at the beginning of

this section.

2 − Set thermostat to lowest setting.

3 − Turn off all electrical power to appliance.

4 − This appliance is equipped with an ignition device

which automatically lights the burners. Do not try to light the burners by hand.

5 − Remove bottom access panel. 6 − Close manual main shut off valve. White Rodgers

Gas Valve −− Switch lever to OFF. See figure 13 or

14. Honeywell Gas Valve −− Turn knob on gas valve

clockwise

to OFF. Do not force. See figure 15.

Honeywell Gas Valve with on / off switch, move switch to OFF. See figure 16.

7 − Wait five (5) minutes to clear out any gas. If you then

smell gas, STOP! Immediately call the gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions. If you do not smell gas go to next step.

8 − Open manual main shut off valve. White Rodgers Gas

Valve −− Switch gas valve lever to ON. See figure 13 or

14. Honeywell Gas Valve −− Turn knob on gas valve coun-

terclockwise

to ON. See figure 15. Do not force.

Honeywell Gas Valve with on / off switch move switch to ON. See figure 16.

9 − Replace access panel.

10− Turn on all electrical power to unit.

11− Set thermostat to desired setting.

12− If the appliance will not operate, follow the instructions

To Turn Off Gas To Unit" .

To Turn Off Gas To Unit"

1 − Set thermostat to lowest setting. 2 − Turn off all electrical power to unit if service is to be per-

formed.

3 − Remove access panel.

4 − Switch lever on White Rodgers gas valve to OFF; turn

knob on Honeywell valve clockwise

to OFF. Do not

force. Honeywell Gas Valve with on / off switch, move switch to OFF. See figure 16.

5 − Replace access panel.

C−Safety or Emergency Shutdown

Disconnect main power to unit. Close manual and main gas valves.

D−Extended Period Shutdown

Turn off thermostat or set to UNOCCUPIED" mode. Close all gas valves (both internal and external to unit) to guarantee no gas leak into combustion chamber. Turn off power to unit. All access panels and covers must be in place and secured.

IV−HEATING SYSTEM SERVICE CHECKS A−C.S.A. Certification

All units are C.S.A. (formally A.G.A. and C.G.A. combined) design certified without modifications. Refer to the G40DF(X) Installation Instruction.

B−Gas Piping

Gas supply piping should not allow more than 0.5"W.C. drop in pressure between gas meter and unit. Supply gas pipe must not be smaller than unit gas connection.

Compounds used on gas piping threaded joints should be resistant to action of liquefied petroleum gases.

C−Testing Gas Piping

CAUTION

If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace cabinet.

IMPORTANT

In case emergency shutdown is required, turn off the main shut-off valve and disconnect the main power to unit. These controls should be properly labeled by the installer.

WARNING

Do not exceed 600 in−lbs (50 ft−lbs) torque when attaching the gas piping to the gas valve.

When pressure testing gas lines, the gas valve must be disconnected and isolated. Gas valves can be damaged if subjected to more than 0.5psig (14" W.C.). See figure 18. If the pressure is equal to or less than 0.5psig (14"W.C.), use the manual shut−off valve before pressure testing to isolate furnace from gas supply.

Page 19

FIGURE 18

MANUAL MAIN SHUT−OFF VALVE

WILL NOT HOLD TEST PRESSURE

IN EXCESS OF 0.5 PSIG (14"W.C.)

GAS VALVE

CAP

GAS PIPING TEST PROCEDURE

FIELD PROVIDED

LINE PRESSURE TAP

When checking piping connections for gas leaks, use preferred means. Kitchen detergents can cause harmful corrosion on various metals used in gas piping. Use of a specialty Gas Leak Detector is strongly recommended. It is available through Lennox under part number 31B2001. See Corp. 8411−L10, for further details.

Do not use matches, candles, flame or any other source of ignition to check for gas leaks.

D−Testing Gas Supply Pressure

When testing supply gas pressure, connect test gauge to inlet pressure tap (field provided). See figure 18. Check gas line pressure with unit firing at maximum rate. Low pressure may result in erratic operation or underfire. High pressure can result in permanent damage to gas valve or overfire. See table 15 for operating pressure at unit gas connection (line).

On multiple unit installations, each unit should be checked separately, with and without units operating. Supply pressure must fall within range listed in previous paragraph.

E−Check Manifold Pressure

After line pressure has been checked and adjusted, check manifold pressure. Move pressure gauge to outlet pressure tap located on unit gas valve (GV1). Checks of manifold pressure are made as verification of proper regulator adjustment. Manifold pressure for the G40DF(X) can be measured at any time the gas valve is open and is supplying gas to the unit. See table 15 for normal operating manifold pressure.

TABLE 15

All G40DF Units

Natural LP

Line Pressure WC" 4.5 − 10.5 11.0 − 13.0

Manifold Pressure WC" 3.5 10.0

IMPORTANT

For safety, connect a shut-off valve between the manometer and the gas tap to permit shut off of gas pressure to the manometer.

The gas valve is factory set and should not require adjustment. All gas valves are factory regulated. See specifications section of this manual for High Altitude manifold pressure settings.

Manifold Adjustment Procedure:

1 − Connect a test gauge to outlet pressure tap on gas

valve. See figures 13, 14 and 15. Start unit and allow 5 minutes for unit to reach steady state.

2 − While waiting for the unit to stabilize, notice the flame.

Natural gas should burn blue. L.P. gas should burn mostly blue with some orange streaks.

3 − After allowing unit to stabilize for 5 minutes, record

manifold pressure.

NOTE−Shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug.

F− Proper Gas Flow (Approximate)

Furnace should operate at least 5 minutes before checking gas flow. Determine time in seconds for two revolutions of gas through the meter. (Two revolutions assures a more accurate time.) Divide by two and compare to time in table 16 below. Adjust manifold pressure on gas valve to match time needed. Manifold pressure should not exceed values listed in table 15. If manifold pressure matches table 15 and rate is incorrect, check gas orifices for proper size and restriction.

NOTE− To obtain accurate reading, shut off all other gas appliances connected to meter.

IMPORTANT

For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug.

TABLE 16

GAS METER CLOCKING CHART

Seconds for One Revolution

G40DF

Natural LP

G40DF

Unit

1 cu ft

Dial

2 cu ft

Dial

1 cu ft

Dial

2 cu ft

DIAL

−45 82 164 205 410

−70 55 110 136 272

−90 41 82 102 204

−110 33 66 82 164

−135 27 54 68 136

G− Proper Combustion

Furnace should operate minimum 15 minutes with correct manifold pressure and gas flow rate before checking combustion. See sections E− and F−. Take combustion sample beyond the flue outlet and compare to table 17. The maximum carbon monoxide reading should not exceed 100 ppm.

Page 20

FIGURE 19

TRANSDUCER

(PART #78H5401)

Page 20

TABLE 17

Unit

CO2%

For Nat

CO2%

For L.P.

24A−45 5.8 − 6.8 6.8 − 7.8

36A−45 5.4 − 6.4 6.10 − 7.10

36A−070 6.6 − 7.6 7.3 − 8.3

36B−090 6.9 − 7.9 8.2 − 9.2

48B−070 6.0 − 7.0 5.7 − 6.7

48C−090 7.2 − 8.2 7.7 − 8.7

48C−110 6.8 − 7.8 7.8 − 8.8

60C−110 6.8 − 7.8 7.8 − 8.8

60D−135 6.9 − 7.9 7.8 − 8.8

H−Flame Signal

A microamp DC meter is needed to check the flame signal on the ignition control.

Flame (microamp) signal is an electrical current which passes from the furnace control through the sensor during unit operation. Current passes from the sensor through the flame to ground to complete a safety circuit.

To Measure Flame Signal − Ignition Control:

A transducer (Part #78H5401 available from Lennox Repair Parts) is required to measure flame signal if meter used will not read a low micro amp signal. Seefigure19. The transducer converts microamps to volts on a 1:1 conversion. See table 18 for flame signal A digital readout meter must be us e d . The tr ansducer plugs into most meters. See figure 20 for proper use of transducer.

1 − Set the volt meter to the DC voltage scale. Insert

transducer into the VDC and common inputs. Observe correct polarities. Failure to do so results in negative (−) values.

2 − Turn off supply voltage to control.

3 − Disconnect ignition control flame sensor wire from the

flame sensor.

4 − Connect (−) lead of the transducer to flame sensor.

5 − Connect (+) lead of transducer to the ignition control sen-

sor wire.

6 − Turn supply voltage on and close thermostat contacts to

cycle system.

7 − When main burners are in operation for two minutes, take

reading. Remember 1 DC volt = 1 DC microamp.

TABLE 18

Flame Signal in Microamps

SureLight

Control

Normal Low Drop Out

56L84 10M90 32M88

 0.18

0.16 − 0.17

 0.15

69M08

 0.31

0.25 − 0.30

 0.24

78M47

100973−01

 1.5

0.5 − 1.4

 0.4

SET DIAL TO

MEASURE VDC

(+)

(−)

(−) TO

FLAME

SENSOR

NOTE−MUST USE DIGITAL METER

RED COLLAR

INDICATES

POSITIVE

LEAD

(+) TO

IGNITION

CONTROL

SENSOR

WIRE

FIGURE 20

WARNING

Fire and explosion hazard. These instructions MUST be followed exactly. Can cause a fire or explosion resulting in property

damage, personal injury or loss of life.

V−TYPICAL OPERATING CHARACTERISTICS A−Blower Operation and Adjustment

NOTE− The following is a generalized procedure and does not apply to all thermostat controls.

1 − Blower operation is dependent on thermostat control

system.

2 − Generally, blower operation is set at thermostat sub-

base fan switch. With fan switch in ON position, blower operates continuously. With fan switch in AUTO position, blower cycles with demand or runs continuously while heating or cooling circuit cycles.

3 − Depending on the type of indoor thermostat, blower

and entire unit will be off when the system switch is in OFF position.

Page 21

FIGURE 21

STATIC PRESSURE TEST

Page 21

B−Temperature Rise

Temperature rise for G40DF(X) units depends on unit input, blower speed, blower horsepower and static pressure as marked on the unit rating plate. The blower speed must be set for unit operation within the range of TEMP. RISE °F" listed on the unit rating plate.

To Measure Temperature Rise:

1 − Place plenum thermometers in the supply and return air

plenums. Locate supply air thermometer in the first horizontal run of the plenum where it will not pick up radiant heat from the heat exchanger.

2 − Set thermostat to highest setting. 3 − After plenum thermometers have reached their high-

est and steadiest readings, subtract the two readings. The difference should be in the range listed on the unit rating plate. If the temperature is too low, decrease blower speed. If temperature is too high, first check the firing rate. Provided the firing rate is acceptable, increase blower speed to reduce temperature. To change blower speed taps see the Blower Speed Taps section in this manual.

C−External Static Pressure

1 − Tap locations shown in figure 21. 2 − Punch a 1/4" diameter hole

in supply and return air plenums. Insert manometer hose flush with inside edge of hole or insulation. Seal around the hose with permagum. Connect the zero end of the manometer to the discharge (supply) side of the system. On ducted systems, connect the other end of manometer to the return duct as above. For systems with non−ducted returns, leave the other end of the manometer open to the atmosphere.

3 − With only the blower motor running and the evaporator

coil dry, observe the manometer reading. Adjust blower motor speed to deliver the air desired according to the job requirements.

4 − External static pressure drop must not be more than

0.5" W.C.

5 − Seal around the hole when the check is complete.

D−Blower Speed Taps

Blower speed tap changes are made on the SureLight control board. See figures 3, 5 and 6. For controls 56L84, 10M93 and 32M88 the heating tap is connected to the HEAT−H" terminal and the cooling tap is connected to the COOL−H" terminal. On controls 69M08 and 78M47 the heating tap is connected to the HEAT" terminal and the cooling tap is connected to t he COOL" terminal. On all units the continuous blower tap is the same as the heating tap and unused taps must be secured on two dummy terminals labeled "PARK.

VI−MAINTENANCE

At the beginning of each heating season, the system should be checked as follows:

A−Filters

All G40DF(X) filters are installed external to the unit. Filters should be inspected monthly. Clean or replace the filters when necessary to ensure that the furnace operates properly. Replacement filters must be rated for high velocity airflow.

B− Heat Exchanger and Burners

Cleaning the Heat Exchanger and Burners

NOTE−Use papers or protective covering in front of furnace while cleaning furnace.

Cleaning the heat exchanger requires a steel spring snake," a reversible drill and a vacuum cleaner. The steel spring snake may be constructed by purchasing a 4 ft. long by 1/4" diameter steel wire cable and a 1/4" diameter wire brush. These items are available at a hardware store. Insert wire end of brush into the open end of the spring cable. Crimp the cable around the brush so that the brush is secured and will not come off during cleaning. Attach the other end of the cable to the reversible drill to complete the tool for cleaning the heat exchanger. See figure 1 for parts arrangement when disassembling furnace.

1 − Turn off both electrical and gas power supplies to fur-

nace.

2 − Remove flue pipe and top cap from unit. Mark and dis-

connect wiring from prove switch and combustion air inducer.

FIGURE 22

G40DF(X) BURNER & HEAT

EXCHANGER REMOVAL

HEAT EXCHANGER

BURNER BOX ASSEMBLY

NOX INSERT

Page 22

3 − Remove four screws securing the combustion air induc-

er. Carefully remove the combustion air inducer and prove switch together as a unit to avoid damaging blower gasket. If gasket is damaged, it must be replaced to prevent leakage.

4 − Remove collector box located behind combustion air

inducer. Care must be taken to avoid damaging the collector box gasket. If the gasket is damaged it must be replaced to prevent leakage.

5 − Mark then disconnect wires from gas valve and rollout

switch.

6 − Disconnect gas supply piping. Remove six screws se-

curing the burner manifold assembly to the lower vestibule panel and remove the assembly from the unit. NO

units only: remove screws holding NO

inserts. Carefully remove inserts from each heat exchanger clam. See figure 22.

7 − Insert brush end of cable snake into top of one of the

heat exchanger openings. DO NOT FORCE CABLE INTO HEAT EXCHANGER. Once the cable has been inserted, operate drill on slow speed. Move the cable in and out of the heat exchanger section three or four times or until sufficient cleaning is accomplished. Reverse drill and slowly work cable out of opening.

8− Repeat procedure for each heat exchanger section. 9− When the top heat exchanger sections are complete,

place brush end of cable snake into the bottom openings of each of the heat exchanger sections. Clean the bottom opening as described in step 7.

10− Remove cable from heat exchanger. Use a vacuum to

remove debris knocked loose during cleaning from each heat exchanger section.

11− Attach the exhaust end (positive pressure) of the

vacuum to the top of the heat exchanger sections. Any loose debris will be forced to the bottom of the heat exchanger section. Vacuum debris from bottom openings.

12− Replace collector box and combustion air inducer/prove

switch combination. Check gaskets for damage. Damaged seals must be replaced to avoid heat exchanger leaks. Replace all screws to the collector box and combustion air inducer. Leaving off screws may cause leaks.

13− Clean burner by running a vacuum with a soft brush at-

tachment over face of burners. Visually inspect inside of burners and crossovers for any blockage caused by foreign matter. Remove any blockage.

14− For NOX units, replace inserts in each heat exchanger

section. DO NOT BEND.

15− Replace burner / manifold assembly onto vestibule

panel.

16− Reconnect wires to pressure switch, roll−out switch, gas

valve and combustion air inducer. Refer to unit wiring diagram.

17− Reconnect vent pipe to combustion blower outlet.

18− Reconnect gas supply piping.

19− Turn on power and gas supply to unit.

20− Set thermostat and check for proper operation.

21− Check all piping connections, factory and field, for gas

leaks. Use a leak detecting solution or other preferred means. Rinse piping after leak test has been completed. Do not use matches, candles, flame or other

sources of ignition to check for gas leaks.

22− If a leak is detected, shut gas and electricity off and

repair leak.

23− Repeat steps 21 and 22 until no leaks are detected.

24− Replace front access panel.

CAUTION

Potential for gas leaks, fire or explosion. Some soaps used for leak detection are corrosive to certain metals. Carefully clean piping thoroughly after leak detection has been completed. Can cause damage to piping resulting in gas leaks, fire or explosion.

C−Supply Air Blower

1 − Check and clean blower wheel. 2 − Motors used on the Lennox G40DF(X) series units

are permanently lubricated and need no further lubrication.

D−Flue and Chimney

Flue must conform to local codes. In the absence of local codes, flue must meet the National Fuel Gas Code ANSI−Z223.1 venting requirements. Flue pipe deteriorates from the inside out and must be disconnected in order to check thoroughly. Check flue pipe, chimney and all connections for tightness and to make sure there is no blockage or leaks.

E−Electrical

1 − Check all wiring for loose connections. 2 − Check for correct voltage. 3 − Check amp−draw on blower motor.

Page 23

VII− Wiring and Sequence of Operation

1 − When there is a call for heat, W1 of the thermostat energizes

W of the furnace control with 24VAC.

2 − S10 primary limit switch, S47 rollout switch and S21 secon-

dary limit are closed. Call for heat can continue.

3 − SureLight control (A92) energizes combustion air inducer

B6. Combustion air inducer runs until S18 combustion air prove switch closes (switch must close within 2−1/2 minutes or control goes into 5 minute Watchguard Pressure Switch delay). Once S18 closes, a 15−second pre−purge follows.

4 − SureLight control (A92) energizes ignitor. A 20−second

warm−up period begins.

5 − Gas valve opens for a 4−second trial for ignition.

6 − Flame is sensed, gas valve remains open for the heat call.

7 − After 45−second delay, SureLight control (A92) energizes in-

door blower B3.

8 − When heat demand is satisfied, W1 of the indoor thermostat

de−energizes W of the SureLight control which de−energizes the gas valve. Combustion air inducer B6 continues a 5−second post−purge period, and indoor blower B3 completes a selected OFF time delay.

Page 24

SuRELight Control 56L84, 10M93, 32M88, 69M08

LED#1 = DS1 LED#2 = DS2

HEATING SEQUENCE OF OPERATION

NORMAL HEATING MODE

ABNORMAL HEATING MODE

CONTROL SELF−CHECK OKAY?

BURNER OFF?

(CONTINUOUS FLAME CHECK)

NORMAL OPERATION:

LED #1 −− SLOW FLASH LED #2 −− SLOW FLASH

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER DELAY OFF.

LED #1 ON LED #2 ON

(RESET CONTROL BY TURNING MAIN POWER OFF.)

POLARITY REVERSED.

LED #1 −− FAST FLASH

LED #2 −− SLOW FLASH

POWER ON

IS POLARITY REVERSED?

ROLLOUT SWITCH CLOSED?

THERMOSTAT CALLS FOR HEAT:

LED #1 −− FAST FLASH LED #2 −− FAST FLASH

IS COMBUSTION AIR

PROVE SWITCH OPEN?

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

LED #1 −− ON. LED #2 −− SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON HEATING SPEED.

LED #1 −− SLOW FLASH

LED #2 −− OFF

GAS VALVE OFF.

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.

LED #1 OFF

LED #2 SLOW FLASH

(Sequence holds until pressure switch

closes or thermostat resets control.)

YES

IS VOLTAGE

ABOVE 75 VOLTS?

LED SIGNALS WAITING ON CALL FROM

THERMOSTAT. CONTROL WILL NOT RESPOND

UNTIL VOLTAGE RISES ABOVE 75 VOLTS.

IS COMBUSTION AIR INDUCER

ENERGIZED?

HAS COMBUSTION AIR PROVE SWITCH

CLOSED IN 2.5 MINUTES?

YES

PROVE SWITCH IS IN WATCHGUARD MODE.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.

LED #1 −− OFF. LED #2 −− SLOW FLASH.

IS 5-MINUTE RESET PERIOD COMPLETE?

PRIMARY AND SECONDARY LIMIT SWITCH.

CLOSED?

YES

CONTINUED NEXT PAGE

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER ON

LED #1 SLOW FLASH RATE

LED #2 −− ON

YES

Page 25

HEATING SEQUENCE CONTINUED

NORMAL HEATING MODE ABNORMAL HEATING MODE

FLAME RECTIFICATION CURRENT

CHECK. CAN FLAME BE PROVEN WITHIN

4 SECONDS AFTER GAS VALVE OPENS?

(See table18)

FLAME PRESENT?

INDOOR BLOWER ON DELAY BEGINS

(45 seconds.)

PRIMARY AND SECONDARY LIMIT

SWITCHES CLOSED?

COMBUSTION AIR PROVE

SWITCH CLOSED?

LOW FLAME SIGNAL

(Does not affect operation of control)

LED #1 −− SLOW FLASH

LED #2 −− FAST FLASH

GAS VALVE DE−ENERGIZED.

COMBUSTION AIR INDUCER DE−ENERGIZED.

INDOOR BLOWER ON UNTIL SWITCH CLOSES.

LED #1 −− SLOW FLASH. LED #2 −− ON.

IS LIMIT SWITCH CLOSED?

GAS VALVE DE−ENERGIZED.

COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF WITH DELAY

LED #1 −− OFF. LED #2 −− SLOW FLASH.

HAS CAB SWITCH CLOSED IN 2.5 MINUTES?

15-SECOND COMBUSTION AIR INDUCER PREPURGE

INITIATED BY CLOSED PROVE SWITCH.

YES

IGNITOR WARM-UP −− 20 SECONDS.

YES

4-SECOND TRIAL FOR IGNITION. GAS VALVE OPENS.

CONTROL 56L84: IGNITOR ENERGIZED FOR 1 SECOND AFTER

VALVE OPENS. CONTROL 10M93, 32M88, 69M08 : IGNITOR

ENERGIZED DURING 4 SECOND TRIAL. NO FLAME SENSED

DURING THIS PERIOD.

YES

FLAME STABILIZATION PERIOD.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF.

HAS CONTROL FAILED TO SENSE FLAME FOR

FIVE CONSECUTIVE TRIES DURING A SINGLE

HEAT DEMAND?

WATCHGUARD MODE. GAS VALVE OFF.

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY

LEDs SIGNAL WATCHGUARD FAILURE CODE.

IS 60-MINUTE RESET PERIOD COMPLETE?

YES

4 SECONDS

YES

HAS CONTROL RESET IGNITION

SEQUENCE FOUR TIMES?

FLAME SIGNAL NORMAL ((See table18)

YES

ROLLOUT SWITCH CLOSED?

GAS VALVE POWER OFF.

COMBUSTION AIR INDUCER POWER ON.

INDOOR BLOWER ON

LED #1 −− ON. LED #2 −− SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET

AND MAIN POWER IS INTERUPTED OR

THERMOSTAT IS CYCLED OFF/ON FOR 1 TO 20 SEC.

YES

THERMOSTAT DEMAND SATISFIED.

LED #1 & #2 SIMULTANEOUS SLOW FLASHES.

COMB. AIR INDUCER CONTINUES 5-SECOND

POST PURGE AFTER T’STAT DEMAND IS SATISFIED.

INDOOR AIR BLOWER COMPLETES SELECTED

OFF" DELAY BEFORE DE−ENERGIZING.

ACCESSORY TERMINALS DE−ENERGIZED.

YES

5-MINUTE PROVE SWITCH

WATCHGUARD MODE.

YES

IS THERE A PROPER GROUND?

IS VOLTAGE ABOVE 75 VOLTS?

IS IGNITOR INTACT AND CONNECTED?

LEDS SIGNAL

ALTERNATING

FAST FLASH

YES

HAS PRIMARY SECONDARY

LIMIT RESET (CLOSED)

WITHIN 3 MINUTES?

LIMIT SWITCH

WATCHGUARD

MODE. GAS VALVE

OFF. COMB. AIR

INDUCER OFF. INDOOR BLOWER OFF WITH DELAY.

LED#1−SLOW

FLASH LED#2− ON.

IS 60−MINUTE

RESET PERIOD

COMPLETE?

YES

Page 26

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE ABNORMAL COOLING MODE

IGNITION CONTROL MAIN POWER ON.

CONTROL SELF DIAGNOSTIC CHECK.

IS CONTROL OPERATING NORMALLY?

YES

SIGNAL POLARITY REVERSED AT LED.

POWER ON

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL CIRCUIT BOARD FAILURE AT LED.

INTERRUPT MAIN POWER TO RESET CONTROL.

YES

IS POLARITY REVERSED?

ROLLOUT SWITCH MONITORED CONTINUOUSLY.

IS ROLLOUT SWITCH CLOSED?

CHECK FOR MAIN BURNER FLAME SENSE.

IS MAIN BURNER FLAME OFF?

LED: SLOW FLASH RATE REMAINS UNCHANGED

THROUGHOUT COOLING CYCLE.

THERMOSTAT CALLS FOR COOLING.

COMPRESSOR CONTACTOR ENERGIZED AND SYSTEM FAN

ENERGIZED. (Control 69M08 ONLY will have a 2 second delay)

COOLING SPEED and EAC TERM. ENERGIZED.

COMPRESSOR OFF.

THERMOSTAT OPENS.

SYSTEM FAN AND ACC. TERM. OFF

WITH 0-SECOND DELAY.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

SIGNAL ROLL-OUT SWITCH OPEN AT LED.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL UNWANTED FLAME SENSED AT LED.

SEQUENCE HOLDS UNTIL FLAME IS NOT SENSED.

IS VOLTAGE

ABOVE 75 VOLTS?

LED SIGNALS WAITING ON CALL FROM

THERMOSTAT. CONTROL WILL NOT RESPOND

UNTIL VOLTAGE RISES ABOVE 75 VOLTS.

YES

Page 27

SURELIGHT CONTROL

CONTINUOUS HEAT SPEED FAN SEQUENCE OF OPERATION

LED: SLOW FLASH RATE REMAINS

UNCHANGED THROUGHOUT SEQUENCE.

MANUAL FAN SELECTION MADE AT THERMOSTAT. CONTROL (G) ENERGIZES HEAT SPEED AND EAC

ACCESSORY TERMINAL.

THERMOSTAT CALLS FOR HEAT (W).

THERMOSTAT CALLS FOR COOLING.

THERMOSTAT OPENS.

SYSTEM FAN SWITCHED TO COOLING SPEED.

EAC TERMINAL REMAINS ENERGIZED.

THERMOSTAT OPENS.

CONTROL (G) ENERGIZES SYSTEM FAN AT

HEATING SPEED. EAC TERMINAL ENERGIZED.

YES

HUM TERMINAL ENERGIZES

WITH COMB. AIR INDUCER.

SYSTEM FAN REMAINS ON HEATING

SPEED WITHOUT INTERUPTION

SYSTEM FAN REMAINS ON HEATING

SPEED AND EAC TERMINAL REAMAIN

ENERGIZED WITHOUT INTERUPTION.

HUM TERM. DE−ENERGIZES WITH COMB. AIR INDUCER

Page 28

1 − When there is a call for heat, W1 of the thermostat energizes

W of the furnace control with 24VAC.

2 − S10 primary limit switch, S47 rollout switch and S21 secon-

dary limit are closed. Call for heat can continue.

3 − Ignition control (A92) energizes combustion air inducer B6.

Combustion air inducer runs until S18 combustion air prove switch closes (switch must close within 2−1/2 minutes or control goes into 5 minute Watchguard Pressure Switch delay). Once S18 closes, a 15−second pre−purge follows.

4 − Ignition control (A92) energizes ignitor. A 20−second warm−

up period begins.

5 − Gas valve opens for a 4−second trial for ignition.

6 − Flame is sensed, gas valve remains open for the heat call.

7 − After 45−second delay, ignition control (A92) energizes in-

door blower B3.

8 − When heat demand is satisfied, W1 of the indoor thermostat

de−energizes W of the ignition control which de−energizes the gas valve. Combustion air inducer B6 continues a 5−second post−purge period, and indoor blower B3 completes a selected OFF time delay.

Page 29

SuerLight Control 78M47 & 100973−01

LED#1 = AN1 LED#2 = AN2

HEATING SEQUENCE OF OPERATION

NORMAL HEATING MODE

ABNORMAL HEATING MODE

CONTROL SELF−CHECK OKAY?

BURNER OFF?

(CONTINUOUS FLAME CHECK)

NORMAL OPERATION:

LED #1 −− SLOW FLASH LED #2 −− SLOW FLASH

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER DELAY OFF.

LED #1 ON LED #2 ON

(RESET CONTROL BY TURNING MAIN POWER OFF.)

POLARITY REVERSED.

LED #1 −− FAST FLASH

LED #2 −− SLOW FLASH

POWER ON

IS POLARITY CORRECT?

ROLLOUT SWITCH CLOSED?

THERMOSTAT CALLS FOR HEAT:

LED #1 −− FAST FLASH LED #2 −− FAST FLASH

IS COMBUSTION AIR

PRESSURE SWITCH OPEN?

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

LED #1 −− ON. LED #2 −− SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES

AND POWER IS RESET OR T’STAT IS INTERRUPTED

FOR MINIMUM OF 1 SECOND.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON HEATING SPEED.

LED #1 −− SLOW FLASH

LED #2 −− OFF

GAS VALVE OFF.

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.

LED #1 OFF

LED #2 SLOW FLASH

(Sequence holds until pressure switch

opens or thermostat resets control.)

YES

IS VOLTAGE

ABOVE 90 VOLTS?

LED SIGNALS LOW VOLTAGE. CONTROL WILL

NOT RESPOND UNTIL VOLTAGE RISES ABOVE

90 VOLTS.

IS COMBUSTION AIR INDUCER

ENERGIZED?

HAS COMBUSTION AIR PRESSURE

SWITCH CLOSED IN 2.5 MINUTES?

YES

PRESSURE SWITCH IS IN WATCHGUARD MODE.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.

LED #1 −− OFF. LED #2 −− SLOW FLASH.

IS 5-MINUTE RESET PERIOD COMPLETE?

PRIMARY AND SECONDARY LIMIT SWITCH.

CLOSED?

YES

CONTINUED NEXT PAGE

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER ON

LED #1 SLOW FLASH RATE

LED #2 −− ON

YES

IS THERE A PROPER GROUND?

YES

IMPROPER GROUND. LED #1 −− ALTERNATING FAST FLASH LED #2 −− ALTERNATING FAST FLASH

YES

Page 30

HEATING SEQUENCE CONTINUED

NORMAL HEATING MODE

ABNORMAL HEATING MODE

FLAME RECTIFICATION CURRENT

CHECK. CAN FLAME BE PROVEN WITHIN

4 SECONDS AFTER GAS VALVE OPENS?

(0.5 microamps)

FLAME PRESENT?

INDOOR BLOWER ON

AFTER 45−SECOND DELAY

PRIMARY AND SECONDARY LIMIT

SWITCHES CLOSED?

COMBUSTION AIR PRESSURE

SWITCH CLOSED?

LOW FLAME SIGNAL

(Does not affect operation of control)

LED #1 −− SLOW FLASH

LED #2 −− FAST FLASH

GAS VALVE DE−ENERGIZED.

COMBUSTION AIR INDUCER DE−ENERGIZED.

INDOOR BLOWER ON UNTIL SWITCH CLOSES.

LED #1 −− SLOW FLASH. LED #2 −− ON.

IS LIMIT SWITCH CLOSED?

GAS VALVE DE−ENERGIZED.

COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF WITH DELAY

LED #1 −− OFF. LED #2 −− SLOW FLASH.

HAS CAB SWITCH CLOSED IN 2.5 MINUTES?

15-SECOND COMBUSTION AIR INDUCER PREPURGE

INITIATED BY CLOSED PRESSURE SWITCH.

YES

IGNITOR WARM-UP −− 20 SECONDS.

YES

4-SECOND TRIAL FOR IGNITION.

GAS VALVE OPENS. IGNITOR ENERGIZED FOR

UP TO 3 SECONDS.

YES

FLAME STABILIZATION PERIOD.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF.

HAS CONTROL FAILED TO SENSE FLAME FOR

FIVE CONSECUTIVE TRIES DURING A SINGLE

HEAT DEMAND?

WATCHGUARD MODE. GAS VALVE OFF.

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY

LEDs SIGNAL WATCHGUARD FAILURE CODE.

IS 60-MINUTE RESET PERIOD COMPLETE?

YES

4 SECONDS

YES

HAS CONTROL RESET IGNITION

SEQUENCE FOUR TIMES?

FLAME SIGNAL 1.5 MICROAMPS OR GREATER?

YES

ROLLOUT SWITCH CLOSED?

GAS VALVE POWER OFF.

COMBUSTION AIR INDUCER POWER ON.

INDOOR BLOWER ON

LED #1 −− ON. LED #2 −− SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET

AND MAIN POWER IS INTERRUPTED OR

THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.

YES

THERMOSTAT DEMAND SATISFIED.

LED #1 & #2 SIMULTANEOUS SLOW FLASHES.

COMB. AIR INDUCER CONTINUES 5-SECOND

POST PURGE AFTER T’STAT DEMAND IS SATISFIED.

INDOOR AIR BLOWER COMPLETES SELECTED

OFF" DELAY BEFORE SHUTTING OFF.

YES

5-MINUTE PRESSURE SWITCH

WATCHGUARD MODE.

YES

IS VOLTAGE ABOVE 90 VOLTS?

LEDS SIGNAL

ALTERNATING

FAST FLASH UNTIL

VOLTAGE IS ABOVE

95 VOLTS, THEN

RESTARTS HEATING

SEQUENCE.

YES

HAS PRIMARY / SECONDARY

LIMIT RESET TIME

EXCEEDED 3 MINUTES?

LIMIT SWITCH WATCHGUARD MODE. GAS VALVE, COMB. AIR INDUCER AND INDOOR BLOW-

ER OFF. LEDs SIGNAL LIMIT SWITCH OPEN UNTIL MAIN

POWER IS

INTERRUPTED OR

T’STAT IS CYCLED

OFF/ON FOR 1

SEC. MINIMUM.

60−MINUTE WATCH-

GUARD PERIOD

STARTS AT TIME

LIMIT CLOSES.

IS 60−MIN. PERIOD

COMPLETE?

YES

Page 31

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE

ABNORMAL COOLING MODE

IGNITION CONTROL MAIN POWER ON.

CONTROL SELF DIAGNOSTIC CHECK.

IS CONTROL OPERATING NORMALLY?

YES

SIGNAL POLARITY REVERSED AT LED. CONTROL

WILL CONTINUE TO CALL FOR COOLING IN THIS

CONDITION.

POWER ON

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL CIRCUIT BOARD FAILURE AT LED.

INTERRUPT MAIN POWER TO RESET CONTROL.

YES

IS POLARITY CORRECT?

ROLLOUT SWITCH MONITORED CONTINUOUSLY.

IS ROLLOUT SWITCH CLOSED?

LED: SLOW FLASH RATE REMAINS UNCHANGED

THROUGHOUT COOLING CYCLE.

THERMOSTAT CALLS FOR COOLING.

COMPRESSOR CONTACTOR AND SYSTEM FAN

ENERGIZED WITH 2-SECOND DELAY

(COOLING SPEED). EAC TERM. ENERGIZED.

COMPRESSOR OFF.

THERMOSTAT OPENS.

SYSTEM FAN AND EAC TERM. OFF

WITH 0-SECOND DELAY. UNITS WITH BOARD

100973−01 FAN OFF AFTER A 45 SECOND DELAY

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

SIGNAL ROLL-OUT SWITCH OPEN AT LED.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES

AND MAIN POWER IS INTERRUPTED OR THERMOSTAT

IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.

IS VOLTAGE

ABOVE 90 VOLTS?

LED SIGNALS LOW VOLTAGE. CONTROL WILL

CONTINUE TO CALL FOR COOLING

IN THIS CONDITION.

YES

IS THERE A PROPER GROUND?

YES

SIGNAL IMPROPER GROUND AT LED.

CONTROL WILL CONTINUE TO CALL FOR COOLING

IN THIS CONDITION.

Page 32

CONTINUOUS HEAT SPEED FAN SEQUENCE OF OPERATION

LED: SLOW FLASH RATE REMAINS

UNCHANGED THROUGHOUT SEQUENCE.

MANUAL FAN SELECTION MADE AT THERMOSTAT.

CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT

SPEED. EAC TERMINAL IS ENERGIZED.

THERMOSTAT CALLS FOR HEAT (W).

THERMOSTAT CALLS FOR COOLING.

THERMOSTAT OPENS.

SYSTEM FAN SWITCHED TO COOL SPEED.

EAC TERM. REMAINS ON.

THERMOSTAT OPENS.

MANUAL FAN SELECTION MADE AT THERMOSTAT.

CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT

SPEED. EAC TERM. ENERGIZED.

YES

HUM TERM. ENERGIZES

WITH COMB. AIR INDUCER.

SYSTEM FAN REMAINS ON

HEATING SPEED.

SYSTEM FAN REMAINS ON

HEATING SPEED.

HUM TERM. DE−ENERGIZES

WITH COMB. AIR INDUCER

Page 33

TROUBLE SHOOTING GUIDE

UPON INITIAL POWER UP, REMOVE ALL THERMOSTAT DEMANDS TO THE UNIT

PROBLEM: 1 UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE

Condition Possible Cause Corrective Action / Comments

1.1

− Both diagnostic lights fail to light up.

1.1.1

Main voltage 120V not supplied to unit.

ACTION 1 − Check 120V main voltage. Determine cause of main power failure.

LED#1−Off LED#2−Off

1.1.2

Miswiring of furnace or improper connections.

ACTION 1 − Check for correct wiring of 120V to power make up box and transformer.

ACTION 2 − Check 24V wiring to control board.

1.1.3

Blown fuse

ACTION 1 − Replace fuse. ACTION 2 − If fuse still blows, check for short.

1.1.4

Door interlock switch failure.

ACTION 1 − Check that door switch is activated when door is closed. ACTION 2 − Check wire connections to switch, replace loose connectors. ACTION 3 − Check continuity of switch in closed position. Replace if defective.

1.1.5

Transformer Failure.

ACTION 1 − Check that transformer output is 24V. Replace if defective.

1.1.6

Failed control board.

ACTION 1 − If all the above items have been checked, replace board.

1.2

− Diagnostic lights flash the roll−out

code.

1.2.1

Roll−out switch open.

ACTION 1 − Manually reset the roll−out switch by pushing the top button. ACTION 2 − Determine the cause of the roll−out switch activation before leaving furnace.

code

1.2.2

Roll−out switch failure.

ACTION 1 − Check continuity across roll−out switch. Replace roll−out switch if switch is reset but does not have continuity.

LED#1−On, LED#2−Slow Flash

1.2.3

LED#2 Slow Flash

Miswiring or improper connections at roll−out switch.

ACTION 1

− Check wiring connections to switch.

1.2.4

24 volt pin connector failure

ACTION 1 − Check pin connector for proper connection to control board. ACTION 2 − Check continuity of the multi plug pin.

1.3

− On initial power−up the comb. air inr

n nriz

ducer does not energize

− Diagnostic lights flash the reverse

polarity code.

1.3.1

120V main power polarity reversed.

ACTION 1 − Check the 120V has line and neutral correctly input into control. ACTION 2 − Reverse the line and neutral at the 120V field connection.

LED#1−Fast Flash, LED#2−Slow Flash.

120V field connection.

1.4

− On initial power up the combustion

air inducer does not energize.

− Diagnostic lights flash normal power

on o

eration.

1.4.1

Open combustion air inducer motor circuit.

ACTION 1 − Check for 120V to combustion air inducer. If no power, check wire and connections.

on operation

LED#1−Slow Flash LED#2−Slow Flash

1.4.2

Failed combustion air inducer motor.

ACTION 1 − If power is present at blower, replace blower.

Page 34

PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE

Condition Possible Cause Corrective Action / Comments

1.5

− Diagnostic lights flash the improper

main ground.

1.5.1

Improper ground to the unit.

ACTION 1 − Check that the unit is properly ground. ACTION 2 − Install a proper main ground to the unit

LED#1−Alternating Fast Flash LED#2−Alternating Fast Flash

1.5.2

120 volt Pin connector is improperly

attached to the circuit board.

ACTION 1 − Check 4−pin connector for proper installation. Correctly insert connector into control.

LED#2 Alternating Fast Flash

1.5.3

Line voltage is below 75V.

(−1 through −9 units)

Line voltage is below 90V.

(−10 and later units)

ACTION 1 − Check that the line voltage is above 75V. Determine cause of voltage drop and supply correct voltage to the control.

1.5.4

Open ignitor circuit.

(−1 through −9 units)

ACTION 1 − Check for correct wiring and loose connections in the ignitor circuit. Check mult−plug connections for correct installation.

1.5.5

Broken or failed ignitor.

(−1 through −9 units)

ACTION 1 − Unplug ignitor and read resistance across ignitor. If resistance does not read between 10.9 and 19.7 ohms, replace the ignitor.

PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES NOT

ENERGIZE

Condition Possible Cause Corrective Action / Comments

2.1

− Unit operates with a cooling or contin-

uous fan demand.

− Combustion air inducer will not start

with a Heating demand.

− Diagnostic lights flash the limit failure

2.1.1

Primary or secondary (if equipped )

limit open.

ACTION 1 − Check continuity across switch(es). Switches reset automatically upon cool down. ACTION 2 − Check for restrictions on blower inlet air (including filter) and outlet air. Determine cause for limit activation before placing unit back in operation.

mode.

LED#1−Slow Flash, LED#2−On

2.1.2

Miswiring of furnace or improper

connections at limit switch(es).

ACTION 1 − Check for correct wiring and loose connections. Correct wiring and/or replace any loose connections.

2.2

− Unit operates with a cooling and con-

tinuous fan demand.

− Combustion air inducer will not start

with a Heating demand.

− Diagnostic lights flash the pressure

2.2.1

Miswiring of furnace or improper

connections to combustion air induc-

er.

ACTION 1 − Check for correct wiring and loose connections. Correct wiring and/or replace any loose connections.

switch failure code.

LED#1−Off, LED#2−Slow Flash

2.2.2

Prove switch stuck closed.

ACTION 1 − Check that the prove switch is open without the combustion air inducer operating. Replace if defective.

Page 35

PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER DOES

NOT ENERGIZE (CONT.).

Condition Possible Cause Corrective Action/Comments

2.3

− Unit operates with a cooling and con-

tinuous fan demand.

− Combustion air inducer will not start

with a Heating demand.

− Diagnostic lights flash the pressure

switch failure code 2.5 minutes after

2.3.1

Miswiring of furnace or improper

connections to combustion air induc-

er.

ACTION 1 − Check for correct wiring and loose connections. Correct wiring and/or replace any loose connections.

switch failure code 2.5 minutes after

heating demand.

LED#1−Off, LED#2−Slow Flash

2.3.2

Combustion air inducer failure.

ACTION 1 − If there is 120V to combustion air inducer and it does not operate, replace combustion air inducer.

PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER

ENERGIZES, IGNITOR IS NOT ENERGIZED.

Condition Possible Cause Corrective Action/Comments

3.1

− Unit operates with a cooling and

continuous fan demand.

− Combustion air inducer energizes

3.1.1

Prove switch does not close due to

incorrect routing of the prove switch

lines.

ACTION 1 − Check that the prove switch lines are correctly routed. Correctly route prove switch lines.

with a heating demand.

− Diagnostic lights flash the pressure

switch failure code 2.5 minutes after heating demand.

3.1.2

Prove switch does not close due to

obstructions in the pressure lines.

ACTION 1 − Remove any obstructions from the the pressure lines and/or taps.

LED#1−Off

3.1.3

Prove switch lines damaged

ACTION 1 − Check prove switch lines for leaks. Replace any broken lines.

LED#1 Off

LED#2−Slow Flash

3.1.4

Condensate in prove switch line.

ACTION 1 − Check prove switch lines for condensate. Remove condensate from lines.

3.1.5

Prove switch does not close due to a

low differential pressure across the

prove switch.

ACTION 1 − Check the differential pressure across the prove switch. This pressure should exceed the set point listed on the switch. ACTION 2 − Check for restricted inlet vent. Remove all blockage. ACTION 3 − Check for proper vent sizing and run length. See installation instructions.

3.1.6

Wrong prove switch installed in the

unit, or prove switch is out of

calibration.

ACTION 1 − Check that the proper prove switch is installed in the unit. Replace prove switch if necessary.

3.1.7

Miswiring of furnace or improper

connections at prove switch.

ACTION 1 − Check for correct wiring and loose connections. Correct wiring and/or replace any loose connections.

3.1.8

Prove switch failure.

ACTION 1 − If all the above modes of failure have been checked, the prove switch may have failed. Replace prove switch and determine if unit will operate.

Page 36

PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER

ENERGIZES, IGNITOR IS ENERGIZED.

Condition Possible Cause Corrective Action/Comments

4.1

− Unit operates with a cooling and

continuous fan demand.

4.1.1

Check that gas is being supplied to

the unit.

ACTION 1 − Check line pressure at the gas valve. Pressure should not exceed 13" WC for both natural and propane. Line pressure should read a minimum 4.5" WC for natural and 8.0"WC for propane.

− Combustion air inducer energizes

with Heating demand.

− Ignitor is energized but unit fails to

light.

4.1.2

Miswiring of gas valve or loose

connections at multi−pin control amp

plugs or valve.

ACTION 1 − Check for correct wiring and loose connections. Correct wiring and/or replace any loose connections.

LED#1−Alternating Slow Flash LED#2−Alternating Slow Flash

4.1.3

Defective gas valve or ignition

control.

ACTION 1 − Check that 24V is supplied to the gas valve approximately 35 seconds after heat demand is initiated. ACTION 2 − Replace the valve if 24V is supplied but valve does not open. ACTION 3 − Replace the control board if 24V is not supplied to valve.

PROBLEM 5: BURNERS LIGHT WITH A HEATING DEMAND BUT UNIT SHUTS DOWN

PREMATURELY

Condition Possible Cause Corrective Action/Comments

5.1

− Burners fire with a heating demand.

− Burners light but unit shuts off prior

to satisfying T−stat demand.

− Diagnostic lights flash the pressure

switch code.

LED#1−Off LED#2−Slow Flash

5.1.1

Low pressure differential at the prove

switch.

ACTION 1 − Check for restricted exhaust vent. Remove all blockage. ACTION 2: Check for proper vent sizing. See installation instructions.

5.2

− Combustion air inducer energizes

with a heating demand.

5.2.1

Sensor or sensor wire is improperly

installed.

ACTION 1 − Check that sensor is properly located and that the sense wire is properly attached to both the sensor and the control.

− Burners light but fail to stay lit.

− After 5 tries the control diagnostics

flash the watchguard burners failed to ignite code.

5.2.2

Sensor or sensor wire is broken.

ACTION 1 − Check for a broken sensor. ACTION 2 − Test continuity across the sense

wire. If wire or sensor are damaged replace the component.

ignite code.

LED#1−Alternating Slow Flash LED#2−Alternating Slow Flash

5.2.3

Sensor or sensor wire is grounded to

the unit.

ACTION 1 − Check for resistance between the sensor rod and the unit ground. ACTION 2 − Check for resistance between the sensor wire and the unit ground.

ACTION 3 − Correct any shorts found in circuit.

5.2.4

Control does not sense flame.

ACTION 1 − Check the microamp signal from the burner flame. If the microamp signal is below normal microamps, check the sensor rod for proper location or contamination. ACTION 2 − Replace, clean, or relocate flame sensor rod. If rod is to be cleaned, use steel wool or replace sensor. DO NOT CLEAN ROD WITH SAND PAPER. SAND PAPER WILL CONTRIBUTE TO THE CONTAMINATION PROBLEM. NOTE: Do not attempt to bend sensor rod. ACTION 3 − Check that there is proper ground to burner box. Repair as necessary.

Page 37

PROBLEM 5: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN

PREMATURELY (CONT.)

Condition Possible Cause Corrective Action/Comments

5.3

− Combustion air inducer energizes

with a heating demand.

− Burners light.

− Roll−out switch trips during the

heating demand.

5.3.1

Unit is firing above 100% of the

nameplate input.

ACTION 1 − Check that the manifold pressure matches value listed on nameplate. See installation instructions for proper procedure. ACTION 2 − Verify that the installed orifice size match the size listed on the nameplate or installation instructions. ACTION 3 − Check the input rate to verify rate matches value listed on nameplate.

− Diagnostic lights flash roll−out fail-

ure.

LED#1−On

5.3.2

Gas orifices leak at the manifold

connection.

ACTION 1 − Tighten orifice until leak is sealed. NOTE: Be careful not to strip orifice threads. ACTION 2 − Check for gas leakage at the

threaded orifice connection. Use approved method for leak detection (see unit instructions).

LED#1 On

LED#2−Slow Flash

5.3.3

Insufficient flow through the heat

exchanger caused by a sooted or

restricted heat exchanger.

ACTION 1 − Check for sooting deposits or other restrictions in the heat exchanger assembly. Clean assembly as outlined in instruction manual. ACTION 2 − Check for proper combustion. See IV− Heating System Service Checks section G−.

5.3.4

Burners are not properly located in

the burner box.

ACTION 1 − Check that the burners are firing into the center of the heat exchanger openings. Correct the location of the burners if necessary.

5.4

− Combustion air inducer energizes

with a heating demand.

5.4.1

Poor Venting

ACTION 1 −Check vent pipe and remove any obstructions ACTION 2 − Check for correct exhaust vent installation. See instructions

− Burners light roughly and the unit

fails to stay lit.

− Diagnostic lights flash watchguard

flame failure.

5.4.2

Improper burner cross−overs

ACTION 1 − Remove burner and inspect the cross−overs for burrs, or any restriction or if crossover is warped. Remove restriction or replace burners.

flame failure

LED#1−Alternatin

Slow Flash

5.4.3

Burrs in gas orifices

ACTION 1 − Remove gas orifices and inspect. Remove any burrs that are present or replace orifice.

LED#1−Alternating Slow Flash

LED#2−Alternating Slow Flash

5.4.4

Prove Switch opens 5 times during a

single demand

ACTION 1 − Inspect vent pipe installation and for any restriction. Remove restriction.

ACTION 2 − Check prove switch reliability.

5.5

− Combustion air inducer energizes

with a heating demand.

− Burners light.

− Diagnostic lights flash watch guard

flame failure.

− NOTE" Unit might go into 60 minute

5.5.1

Loose sensor wire connection causes

intermittent loss of flame signal.

ACTION 1 − Check that the sensor is properly located. ACTION 2 − Check that the sense wire is properly attached to both the sensor and the control. Pay extra attention to the pin connectors.

Watchguard mode depending on intermittent nature of sensor signal.

LED#1−Alternating Slow Flash LED#2−Alternating Slow Flash

5.5.2

Poor ground to burner box

ACTION 1 − Check for proper ground and repair as necessary.

Page 38

PROBLEM 6: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE

Condition Possible Cause Corrective Action/Comments

6.0

− Unit operates correctly but the diag-

nostic lights flash low flame sense

6.1.1

Sensor rod is improperly located on

the burner.

ACTION 1 − Check the sensor rod for proper location on the burner. Properly locate the sensor rod or replace if rod cannot be located correctly.

code

LED#1−Slow Flash LED#2−Fast Flash

6.1.2

Sensor rod is contaminated.

ACTION 1 − Check sensor rod for contamination or coated surface. Clean the sensor rod with steel wool or replace sensor. DO NOT USE SAND PAPER TO CLEAN ROD. SAND PAPER WILL CONTRIBUTE TO THE CONTAMINATION PROBLEM.

PROBLEM 7: INDOOR BLOWER FAILS TO OPERATE IN COOLING, HEATING, OR CONTINUOUS

FAN MODE

Condition Possible Cause Corrective Action/Comments

7.0

− Indoor blower fails to operate in

continuous fan, cooling, or heating mode.

7.1.1

Miswiring of furnace or improper

connections at control or indoor

blower motor.

ACTION 1− Correct wiring and/or replace any loose connections. Check for correct wiring and loose connections.

7.1.2

120V is not being supplied to the

indoor air blower or blower motor

failure.

ACTION 1 − Check for 120V at the various calls for indoor blower by energizing "Y", "G", and "W" individually on the low voltage terminal strip. Note that when "W’ is energized, the blower is delayed 45 seconds. If there is 120V to each motor tap but the blower does not operate, replace the motor.

7.1.3

Defective control board

ACTION 1 − If there is not 120V when "Y", "G", or "W" is energized, replace the control.

7.1.4

Defective run capacitor

ACTION 1 − Replace capacitor

PROBLEM 8: RF STATIC DURING TIME FOR IGNITION

Condition Possible Cause Corrective Action/Comments

8.0

− AM radio interference.

8.1.2

Ignitor operation

ACTION 1 − Call Technical Support, Dallas.

Lennox G40DF-36A-070X, G40DF-36A-045, G40DF-48B-070, G40DF-36B-090, G40DF-48C-090 Unit Information

Specifications and Main Features

Frequently Asked Questions

User Manual