Page 1
service and
376CAV
maintenance procedures
GAS-FIRED
INDUCED-COMBUSTION FURNACE
NOTE: Read the entire instruction manual before performing any
service or maintenance.
This symbol → indicates a change since the last issue.
These procedures are for size 45,000 through 155,000 Btuh input
units.
Index Page
SAFETY CONSIDERATIONS..................................................1-2
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS
PROCEDURE...........................................................................2
CARE AND MAINTENANCE................................................2-11
Air Filter Arrangement..........................................................2-3
Blower Motor and Wheel......................................................3-4
Cleaning Heat Exchanger......................................................4-5
Electrical Controls and Wiring .............................................5-6
Troubleshooting...................................................................6-11
Unit Wiring Diagram................................................................8
Service Label ............................................................................9
Troubleshooting Guide......................................................10-11
395CAV
Series G
Cancels: SP04-45 SP04-54
9-98
A94087
Fig. 1—Model 376CAV Horizontal
®
SAFETY CONSIDERATIONS
Installing and servicing heating equipment can be hazardous due to
gas and electrical components. Only trained and qualified personnel should install, repair, or service heating equipment.
Untrained personnel can perform basic maintenance functions
such as cleaning and replacing air filters. All other operations must
be performed by trained service personnel. When working on
heating equipment, observe precautions in the literature, on tags,
and on labels attached to or shipped with the unit and other safety
precautions that may apply.
Follow all safety codes. In the United States, follow all safety
→
codes including the National Fuel Gas Code (NFGC) NFPA No.
54-1996/ANSI Z223.1-1996. In Canada, refer to the current
edition of the National Standard of Canada CAN/CGA-B149.1and .2-M95 Natural Gas and Propane Installation Codes (NSCNGPIC). Wear safety glasses and work gloves. Have fire extinguisher available during start-up and adjustment procedures and
service calls.
Recognize safety information. This is the safety-alert symbol
When you see this symbol on the furnace and in instructions or
manuals, be alert to the potential for personal injury.
Understand the signal words DANGER, WARNING, and CAUTION. These words are used with the safety-alert symbol. DANGER identifies the most serious hazards which will result in severe
personal injury or death. WARNING signifies a hazard which
could result in personal injury or death. CAUTION is used to
identify unsafe practices which would result in minor personal
injury or product and property damage. NOTE is used to highlight
suggestions which will result in enhanced installation, reliability,
or operation.
.
—1—
ama
CANADIAN GAS ASSOCIATION
APPROVED
R
A94085
Fig. 3—Model 395CAV
Upflow
A94086
Fig. 2—Model 376CAV
Downflow
REGISTERED QUALITY SYSTEM
Page 2
WARNING: The ability to properly perform maintenance on this equipment requires certain expertise, mechanical skills, tools, and equipment. If you do not
possess these, do not attempt to perform any maintenance
on this equipment other than those procedures recommended in the User’s Manual. FAILURE TO FOLLOW
THIS WARNING COULD RESULT IN POSSIBLE
DAMAGE TO THIS EQUIPMENT, SERIOUS PERSONAL INJURY, OR DEATH.
WARNING: Never store anything on, near, or in contact
with the furnace, such as:
1. Spray or aerosol cans, rags, brooms, dust mops,
vacuum cleaners, or other cleaning tools.
2. Soap powders, bleaches, waxes or other cleaning
compounds, plastic or plastic containers, gasoline, kerosene, cigarette lighter fluid, dry cleaning fluids, or other
volatile fluids.
3. Paint thinners and other painting compounds, paper
bags, or other paper products.
A failure to follow this warning could result in corrosion
of the heat exchanger, fire, personal injury, or death.
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS
PROCEDURE
CAUTION: Electrostatic discharge can affect electronic
components. Take precautions during furnace installation
and servicing to protect the furnace electronic control.
Precautions will prevent electrostatic discharges from
personnel and hand tools which are held during the
procedure. These precautions will help to avoid exposing
the control to electrostatic discharge by putting the
furnace, the control, and the person at the same electrostatic potential.
1. Disconnect all power to the furnace. DO NOT TOUCH
THE CONTROL OR ANY WIRE CONNECTED TO THE
CONTROL PRIOR TO DISCHARGING YOUR BODY’S
ELECTROSTATIC CHARGE TO GROUND.
2. Firmly touch a clean, unpainted, metal surface of the
furnace chassis which is close to the control. Tools held in
a person’s hand during grounding will be satisfactorily
discharged.
3. After touching the chassis you may proceed to service the
control or connecting wires as long as you do nothing that
recharges your body with static electricity (for example; DO
NOT move or shuffle your feet, DO NOT touch ungrounded objects, etc.).
4. If you touch ungrounded objects (recharge your body with
static electricity), firmly touch furnace again before touching control or wires.
5. Use this procedure for installed and uninstalled (ungrounded) furnaces.
6. Before removing a new control from its container, discharge your body’s electrostatic charge to ground to protect
the control from damage. If the control is to be installed in
a furnace, follow items 1 through 5 before bringing the
control or yourself into contact with the furnace. Put all
used AND new controls into containers before touching
ungrounded objects.
7. An ESD service kit (available from commercial sources)
may also be used to prevent ESD damage.
CARE AND MAINTENANCE
WARNING: Turn off the gas and electrical supplies to
the unit before performing any maintenance or service.
Follow the operating instructions on label attached to
furnace. A failure to follow this warning could result in
personal injury.
The minimum maintenance that should be performed on this
equipment is as follows:
1. Check and clean air filter each month or more frequently if
required. Replace if torn.
2. Check blower motor and wheel for cleanliness each heating
and cooling season. Clean and lubricate as necessary.
3. Check electrical connections for tightness and controls for
proper operation each heating season. Service as necessary.
CAUTION: As with any mechanical equipment, personal injury can result from sharp metal edges, etc.,
therefore, be careful when removing parts.
A. Air Filter Arrangement
The air filter arrangement may vary depending on the application.
Refer to Table 1 or 2 for filter size information.
TABLE 1—FILTER SIZE INFORMATION FOR
DOWNFLOW/HORIZONTAL FURNACES (IN.)
FURNACE
CASING WIDTH
14-3/16 (2) 14 X 20 X 1 Cleanable
17-1/2 (2) 14 X 20 X 1 Cleanable
21 (2) 16 X 20 X 1 Cleanable
24-1/2 (2) 16 X 20 X 1 Cleanable
FILTER QUANTITY
AND SIZE
FILTER
TYPE
TABLE 2—FILTER SIZE INFORMATION FOR UPFLOW
FURNACES (IN.)
FURNACE
CASING WIDTH
14-3/16 (1) 16 X 25 X 1* (1) 14 X 25 X 1 Cleanable
17-1/2 (1) 16 X 25 X 1* (1) 16 X 25 X 1 Cleanable
21 (1) 16 X 25 X 1 (1) 20 X 25 X 1* Cleanable
24-1/2 (2) 16 X 25 X 1* (1) 24 X 25 X 1 Cleanable
* Factory-provided with the furnace. Filters may be field modified as required
by cutting and folding the frame as indicated on the filter.
FILTER QUANTITY AND SIZE
Side Return Bottom Return
FILTER
TYPE
For continuing high performance and to minimize possible equipment failure, it is essential that periodic maintenance be performed
on this equipment. Consult your local dealer as to the proper
frequency of maintenance and the availability of a maintenance
contract.
WARNING: Never operate unit without a filter or with
filter access door removed. A failure to follow this
warning could result in fire, personal injury, or death.
—2—
Page 3
AIRFLOW
Fig. 4—Horizontal Filter Arrangement
AIRFLOW
INSTALLATION
POSITION
OF FILTERS
RETURN-AIR
PLENUM
ACCESS DOOR
Fig. 5—Downflow Filter Arrangement
1. Downflow/Horizontal
Each furnace requires 2 filters which are installed in the
return-air duct. (See Fig. 4 and 5.) To remove filters for
cleaning or replacement, proceed as follows:
a. Disconnect electrical power before removing blower
access door.
b. Remove 2 screws from front of door and remove blower
access door.
c. Reach up behind top plate, tilt filters toward center of
return-air plenum, remove filters, and clean as needed.
Replace if torn.
d. Furnaces are equipped with permanent, washable filters.
Clean filters with tap water. Spray water through filter in
opposite direction of airflow.
e. Rinse and let dry. Oiling or coating of filters is not
recommended or required.
f. Reinstall filters.
A94307
A88486
g. Replace blower access door.
h. Restore electrical power to furnace.
2. Upflow
Each furnace requires 1 or 2 filters which are installed in the
blower compartment. (See Fig. 6.) To remove filters for
cleaning or replacement, proceed as follows:
a. Disconnect electrical power before removing access
doors.
b. Remove blower and control access doors.
c. Release filter retainer from clip at front of furnace
casing. (See Fig. 6.) For side return, clips may be used on
either or both sides of the furnace.
d. Slide filter(s) out.
e. Furnaces are equipped with permanent, washable filters.
Clean filters with tap water. Spray water through filter in
opposite direction of airflow.
f. Rinse and let dry. Oiling or coating of filter is not
recommended or required.
g. Reinstall filter(s).
h. Replace blower and control access doors.
i. Restore electrical power to furnace.
B. Blower Motor and Wheel
For long life, economy, and high efficiency, clean accumulated dirt
and grease from the blower wheel and motor annually.
The following steps should be performed by a qualified service
technician.
Some motors have prelubricated sealed bearings and require no
lubrication. These motors can be identified by the absence of oil
ports on each end of the motor. For those motors with oil ports,
lubricate motor every 5 years if motor is used on intermittent
operation (thermostat FAN in AUTO mode), or every 2 years if
motor is in continuous operation (thermostat FAN in ON mode).
NOTE: Remember to disconnect the electrical supply before
removing access doors.
Clean and lubricate as follows:
1. Remove 2 screws from blower access door
(downflow/horizontal furnace only) and remove blower
access door.
2. Remove vent pipe enclosure (downflow/horizontal furnace
only) and disconnect short piece of vent pipe from relief
box.
3. Disconnect wires from auxiliary limit on blower housing
(downflow/horizontal furnace only).
4. Remove control.
5. Disconnect electrical leads from control. (See Fig. 6 or 7.)
Note location of wires for reassembly.
6. Remove screws holding blower assembly to blower deck
and slide blower assembly out of furnace.
7. Loosen screw in strap holding motor capacitor to blower
housing and slide capacitor out from under strap.
8. Mark blower wheel, motor, and motor support in relation to
blower housing before disassembly to ensure proper reassembly.
9. Loosen setscrew(s) holding blower wheel on motor shaft.
10. Remove bolts holding motor mount to blower housing and
slide motor and mount out of housing. Disconnect ground
wire attached to blower housing before removing motor.
11. Lubricate motor (when oil ports are provided).
—3—
Page 4
MOUNTING
SCREWS
RELIEF
BOX
BLOCKED
VENT
SAFEGUARD
FLUE
COLLECTOR
BOX
AUXILIARY
LIMIT
SWITCH
(WHEN USED)
MOUNTING
SCREWS
VENT PIPE
ENCLOSURE
CONTROL
HUM
C
24V
OM
GRYW
BOARD
CONTROL
HUM
C
24V
OM
GRYW
FILTER
RETAINER
WASHABLE
FILTER
→ Fig. 6—Model 395CAV Upflow
a. Remove dust caps or plugs from oil ports located at each
end of motor.
b. Use a good grade of SAE 20 nondetergent motor oil and
put 1 teaspoon, 5 cc, 3/16 oz, or 16 to 25 drops in each
oil port. Do not over-oil.
c. Allow time for total quantity of oil to be absorbed by
each bearing.
d. Wipe excess oil from motor housing.
e. Replace dust caps or plugs on oil ports.
12. Remove blower wheel from housing.
a. Mark cutoff location to ensure proper reassembly.
b. Remove screws holding cutoff plate and remove cutoff
plate from housing.
c. Lift blower wheel from housing through opening.
13. Clean blower wheel and motor using a vacuum cleaner with
soft brush attachment. Do not remove or disturb balance
weights (clips) on blower wheel blades. The blower wheel
should not be dropped or bent as balance will be affected.
14. Reinstall blower wheel by reversing items 12 a through c.
Be sure wheel is positioned for proper rotation.
15. Reassemble motor and blower by reversing items 5 through
10. If motor has ground wire, be sure it is connected as
before.
CAUTION: Be sure the motor is properly positioned in
the blower housing. The motor oil ports must be at a
minimum of 45° above the horizontal centerline of the
motor after the blower assembly has been reinstalled in
the furnace.
16. Reinstall blower assembly in furnace.
17. Reinstall control. Connect blower electrical leads to control.
Please note that the common wire connection is 3/16 in. and
all other wire connections are 1/4 in. for assembly. DO
NOT FORCE.
18. Reconnect wires to auxiliary limit switch on blower housing
(downflow/horizontal furnace only).
19. Reinstall vent pipe and enclosure (downflow/horizontal
furnace only).
A98528
—4—
BLOCKED
VENT
RELIEF
SAFEGUARD
BOX
MANUAL
RESET LIMIT
SWITCHES
→ Fig. 7—Model 376CAV Downflow
20. Turn on electrical power and check for proper rotation and
speed changes between heating and cooling.
21. Replace blower access door. Secure with 2 screws
(downflow/horizontal furnace only).
C. Cleaning Heat Exchanger
The following steps should be performed by a qualified service
technician.
NOTE: Deposits of soot and carbon indicate the existence of a
problem which needs to be corrected. Take action to correct the
problem.
If it becomes necessary to clean the heat exchanger because of
carbon deposits, soot, etc., proceed as follows:
1. Turn off gas and electrical power to furnace.
2. Remove 2 screws from front of blower access door
(downflow/horizontal furnace only) and remove control and
blower access doors.
3. Remove vent pipe enclosure (downflow/horizontal furnace
only) and disconnect vent pipe from relief box.
4. Remove 2 screws that secure relief box. (See Fig. 6 or 7.)
5. Disconnect wires to the following components.
→
a. Blocked vent safeguard
b. Inducer motor
c. Pressure switch
d. Limit overtemperature switch(es)
e. Gas valve
f. Hot surface ignitor
g. Flame-sensing electrode
h. Two wiring connectors leading to control
6. Remove 8 screws that secure flue collector box to center
panel. Be careful not to damage sealant.
7. Remove complete inducer assembly from furnace, exposing
flue openings.
8. Clean cells using field-provided small wire brush, steel
spring cable, reversible electric drill, and vacuum cleaner.
a. Assemble wire brush and steel spring cable.
(1.) Use 48 in. of 1/4-in. diameter high-grade steel
spring cable (commonly known as drain clean-out
or Roto-Rooter cable).
A98529
Page 5
(2.) Use 1/4-in. diameter wire brush (commonly known
as 25-caliber rifle cleaning brush).
NOTE: The materials needed in items (1.) and (2.) can usually be
purchased at local hardware stores.
(3.) Insert twisted wire end of brush into end of steel
spring cable, and crimp tight with crimping tool or
strike with ball-peen hammer. TIGHTNESS is very
important.
(4.) Remove metal screw fitting from wire brush to
allow insertion into cable.
b. Clean each heat exchanger cell.
(1.) Attach variable-speed, reversible drill to end of
steel spring cable (end opposite brush).
(2.) Insert brush end of cable into upper opening of cell
and slowly rotate with drill. DO NOT force cable.
Gradually insert at least 36 in. of cable into 2 upper
passes of cell. (See Fig. 8.)
CAUTION: Be very careful when removing the burner
assembly to avoid breaking the ignitor. See Fig. 9 for the
correct ignitor location.
(5.) Replace screws in center panel and cells before
cleaning.
(6.) Insert brush end of cable in lower opening of cell,
and proceed to clean 2 lower passes of cell in same
manner as 2 upper passes.
(7.) Repeat foregoing procedures until each cell in
furnace has been cleaned.
(8.) Remove residue from each cell using vacuum
cleaner.
→
(9.) Clean burner assembly using vacuum cleaner with
soft brush attachment.
(10.) Clean flame sensor with fine sandpaper.
(11.) Reinstall cell inlet plates and burner assembly.
Care must be exercised to center the burners in the
cell openings.
9. After cleaning flue openings, check sealant on flue collector
to ensure that it has not been damaged. If new sealant is
needed, contact your dealer or distributor.
A91252
Fig. 8—Cleaning Heat Exchanger Cell
11
CELL
PANEL
HOT
SURFACE
IGNITOR
ASSEMBLY
C
IGNITOR
L
7
8
"
C
BURNER
L
IGNITOR
ASSEMBLY
32
"
A93347
BURNER
13
32
"
Fig. 9—Position of Ignitor to Burner
(3.) Work cable in and out of cell 3 or 4 times to obtain
sufficient cleaning. DO NOT pull cable with great
force. Reverse drill and gradually work cable out.
(4.) Remove burner assembly and cell inlet plates.
10. Clean and replace flue collector assembly, making sure all
8 screws are secure.
11. Reinstall relief box.
12. Reconnect wires to the following components.
→
a. Blocked vent safeguard
b. Inducer motor
c. Pressure switch
d. Limit overtemperature switch(es)
e. Gas valve
f. Hot surface ignitor
g. Flame-sensing electrode
h. Two wiring connectors leading to control
13. Reconnect vent pipe to relief box. Replace vent pipe
enclosure (downflow/horizontal furnace only).
14. Replace blower access door only.
15. Turn on electrical power and gas.
16. Set thermostat and check furnace for proper operation.
WARNING: Never use a match or other open flame to
check for gas leaks. Use a soap-and-water solution. A
failure to follow this warning could result in fire, personal
injury, or death.
17. Check for gas leaks.
18. Replace control access door on upflow furnace.
19. On downflow/horizontal furnaces, remove blower access
door, replace control access door first, then replace blower
access door and secure with 2 screws in front of door.
—5—
Page 6
D. Electrical Controls and Wiring
CAUTION: There may be more than 1 electrical supply
to the unit. Check accessories and cooling unit for
additional electrical supplies.
The electrical ground and polarity for 115-v wiring must be
maintained properly. Refer to Fig. 10 for field wiring information
and to Fig. 12 for unit wiring information.
NOTE: If the polarity is not correct, the STATUS LED on the
control center will flash rapidly and prevent the furnace from
operating. The control system also requires an earth ground for
proper operation of the control board and flame-sensing electrode.
The 24-v circuit contains an automotive-type, 3-amp fuse located
on the control board. (See Fig. 11.) Any direct shorts of the 24-v
wiring during installation, service, or maintenance will cause this
fuse to blow. If fuse replacement is required, use ONLY a fuse of
identical size.
With power to the unit disconnected, check all electrical connections for tightness. Tighten all screws on electrical connections. If
any smoky or burned connections are found, disassemble the
connection, clean all parts, strip wire, and reassemble properly and
securely.
Reconnect electrical power to the unit and observe unit through 1
complete operating cycle. Electrical controls are difficult to check
without proper instrumentation; if there are any discrepancies in
the operating cycle, contact your dealer and request service.
For an explanation of fault codes, refer to service label located on
blower access door or Fig. 13, and the troubleshooting guide.
The control center stores 1 fault code (the last fault to occur) for a
period of 48 hrs or until the 115- or 24-v power is interrupted.
NOTE: Removing blower access door will open blower access
door switch and terminate 115-v power to control center, and fault
code will be erased. Look into blower access door sight glass for
current LED status.
1. To retrieve fault code, proceed with the following:
NOTE: NO thermostat signal may be present at control center,
and all blower time delay off periods must be completed.
a. Leave 115-v power to furnace turned on.
b. Look into blower access door sight glass for current
LED status.
NOTE: Leave blower access panel installed to maintain power to
control center to view current LED status.
c. Remove control access door.
d. BRIEFLY remove either wire from the main limit switch
until LED goes out, then reconnect it.
NOTE: If wire to main limit is disconnected longer than 4 sec,
main blower starts, and retrieval request is ignored.
2. When above items have been completed, the following will
occur:
a. LED flashes a fault code 4 times. Record this fault code
for further troubleshooting.
b. Inducer motor starts and continues to run the entire
component test.
c. Hot surface ignitor is energized for 15 sec, then de-
energized.
d. Main blower operates at cooling speed for 10 sec, then
turns off.
e. Main blower operates at heating speed for 10 sec, then
turns off.
f. Inducer motor stops.
Items a through e above will assist in furnace troubleshoot-
ing since all components are functionally operated except
the gas valve. This procedure is also referred to as "Component Test."
3. Operate furnace through 1 heat cycle to test for proper
operation and check LED status.
4. If furnace is operating properly and LED indicates proper
operation, replace control access door.
5. Component Test can also be initiated by performing the
following:
a. Remove control access door.
b. Remove blower access door.
c. Manually close blower access door switch.
WARNING: Blower access door switch opens 115-v
power to control center. No component operation can
occur. Caution must be taken when manually closing this
switch for service purposes. Failure to follow this warning could result in personal injury or death.
d. BRIEFLY short (jumper) TEST, 1/4-in. quick-connect
terminal on control center (adjacent to LED diagnostic
light), and Com terminal on thermostat connection
block. (See Fig. 11.)
NOTE: If TEST to Com terminals are jumpered longer than 2 sec,
LED will flash rapidly, and retrieval request will be ignored.
e. Component Test will function as described in item 2
above.
f. Check LED status.
g. If LED status indicates proper operation, release blower
access door switch, replace blower access door, and
replace control access door.
E. Troubleshooting
Refer to the service label. (See Fig. 13.) Pages 10 and 11 contain
a troubleshooting guide. This guide can be a useful tool in isolating
furnace operation problems. Beginning with the word "Start,"
answer each question and follow the appropriate arrow to the next
item.
The guide will help to identify the problem or failed component.
After replacing any component, verify correct operation sequence.
—6—
Page 7
BLK
WHT
WHT
GND
115-V
FIELD-SUPPLIED
DISCONNECT
THREE-WIRE
BLK
AUXILIARY
J-BOX
FIELD 24-V WIRING
FIELD 115-, 208/230-, 460-V WIRING
FACTORY 24-V WIRING
FACTORY 115-V WIRING
FIVE
WIRE
NOTE 2
WCR GY
THERMOSTAT
TERMINALS
HEATING-
ONLY
W
R
GND
CONTROL
BOX
FURNACE
G
C
Y
24-V
TERMINAL
BLOCK
NOTE 1
CONDENSING
UNIT
TWO
WIRE
NOTES: Connect Y-terminal as shown for proper operation.
1.
2.
Some thermostats require a "C" terminal connection as shown.
3.
If any of the original wire, as supplied, must be replaced, use
same type or equivalent wire.
→ Fig. 10—Heating and Cooling Application Wiring Diagram
FIELD-SUPPLIED
DISCONNECT
208/230- OR
460-V
THREE
PHASE
208/230-V
SINGLE
PHASE
GND
A98209
115-VAC (L1)
POWER
SUPPLY
HOT SURFACE
CONNECTOR
TEST/TWIN
SEC-1
3-AMP FUSE
COOL
HEAT
IGNITOR
BLOWER OFF DELAY
ADJUSTMENT SWITCH
G
R
Y
W
Com
24V
HUM
24V THERMOSTAT
TERMINALS
HUMIDIFIER TERMINAL
(24-VAC 0.5 AMP MAX)
LED OPERATION &
STATUS LIGHT
HARNESS CONNECTOR
24V TRANSFORMER SEC-2
SPARE 1
BLOWER SPEED
SELECTION TERMINALS
SPARE 2
EAC 1 (BLACK)
EAC-ELECTRONIC AIR CLEANER
TERMINALS (115-VAC 1.5 AMP MAX)
EAC 2 (WHITE)
115-VAC (L2) NEUTRAL
CONNECTION
INDUCER MOTOR
CONNECTOR
Fig. 11—Control Board
A93052
—7—
Page 8
L2
CAP
BLWM
START
OL
LO
SCHEMATIC DIAGRAM
(NATURAL GAS & PRO PANE)
NOTE # 4
TO 115VAC FIELD DISCONN ECT
NEUTRAL
L1
(WHEN USED)
NOTE #11
(WHEN USED)
NOTE #14
(WHEN USED)
GRY
SW2
BLOWER
EQUIPMENT GROUND
LGPS
PRS
ALS
BVSS
DSS
OFF
NOTE #9
PCB
HI
MED LO
MED HI
COM
NOTE #7
COM
COOL
HEAT
SPARE-1
SPARE-2
HI/LO
EAC-1
BLWR
L1
ILK
YEL
3-P
NOTE #13
1-M
ORN
ORN
ORN
NOTE #14
LS
ORN
ORN
OM
W
C
SW1
DELAY
(NOT ON ALL MODELS)
BLOWER OFF DELAY
HUM
BLU
RED
LED
TEST/TWIN
90 SEC
135 SEC
180 SEC
SELECTION CHART
IDM
HSI
2
1
PL52
1
PL2
EAC-2
IDR
HSIR
GV
NOTE #5
2-C
GRN
FL
BLK
FRS2
WHT
4
5
6
BLU
FRS1
FSE
RED
SEC-2
987
SEC-1
(WHEN USED)NOTE #11
321
PL1
HI/LO
GVR
225 SEC
NOT USED
PL3
2
1
3
PR2
24VAC
115VAC
TRAN
PR1
GRN
WHT (COM )
WHT
BRN
TRAN
RED
BLK (HI)
SPARE-1
FUSE
24 VAC-3A
COOL
FU1
SPEED
BLOWER
RELAY
HSIR IDR BLWR
FL
PRS
NOTE #13
LS
(WHEN USED)
LGPS
(WHEN USED)
NOTE #11
FRS1 FRS2
(WHEN USED)
7
SEC-2
SEC-1
GVR-2
NOTE #6
FU1
HUM
TEST/TWIN
NOTE #12
CAP
START
OL
NOTE #7
BLU (MED LO)
YEL (MED HI)
SPARE-2
EAC-1
HEAT
L2
PR2
SELECT
123
PL3
PL2
VAC
PL1
NOTE #13
1
4
W
R
BRN
BLWM
BLK
WHT
RED (LO)
WHT (COM)
1.5 AMP
EAC-2
OM
C
WHT
2
1
PR1
L1
120
ALS
NOTE #5
NOTE #11
(WHEN USED)
BVSS
NOTE #14
DSS
GVR
HI/LO
BLWR
IDR
HSIR
NOTE #4
FUSED DISCONNECT
SWITCH (WHEN REQ'D)
JB
GV
NOTE #14
3-P
2
3
GVR-1
CPU
L1
NEUTRAL
FU2
GRN
WHT
BLK
GRN
FSE
2-C
1-M
NOT USED
8
Y
NOT USED
9
6
5
OM
G
C
NOTES:
optimum speed selection.
1. If any of the original equipment wire is replaced use wire rated for 105˚C.
2. Inducer (IDM) and blower (BLWM) motors contain internal auto-reset thermal overload sw itches (OL).
3. Blower motor speed se lections are for average conditions, see installation instructions for details on
4. Use only copper wire between the disconnect switch and the furnace junction box (JB).
JUNCTION
UNMARKED TERMINAL
PCB TERMINAL
(135 seconds only on some models)
after three hours.
9. Blower-off delay, gas heating 90, 135, 180 or 225 seconds, cooling or heat pump 90 seconds.
FIELD WIRING (24VAC)
models only.
10. Ignition-lockout will occ u r after four consecutive unsuccessful trials-for-ignition. Control will auto-reset
11. When used, auxiliary limit switch (ALS) is on som e downflow models only. W hen used, FL is on upflow
CONDUCTOR ON PCB
FIELD WIRING TERMINAL
FIELD GROUND
12. Some models may have spade quick connect terminals.
EQUIPMENT GROUND
5. This wire must be connected to furnace sheetmetal for control to detect flame.
6. Replace only with a 3 amp fuse.
7. Yellow lead not on all motors.
8. Blower-on delay, gas heating 45 seconds, cooling or hea t pump 2 seconds.
FACTORY WIRING (115VAC)
FACTORY WIRING (24VAC)
FIELD WIRING (115VAC)
A98200e
322869-101 REV. E
installed.
13. Factory connected when LG PS is not used.
14. Factory connected when BV SS is not used. B VSS used when Chimney Adapter Accessory Kit is
FIELD SPLICE
PLUG RECEPTACLE
→ Fig. 12—Unit Wiring Diagram
PCB PRINTED CIRCUIT BOARD
PL1 9-CIRCUIT CONNECTOR
PL2 2-CIRCUIT PCB CONNECTOR
PL3 3-CIRCUIT IDM CONNECTOR
PL5 2-CIRCUIT HSI/PCB CONNECTOR
PRS PRESSURE SWITCH, SPST-(N.O.)
TEST/TWIN COMPONENT TEST & TWIN TERMINAL
ILK
IDM
WHT
BLK
PL5
WHT
BLK
BLK
BLK
12
HSI
ALS AUXILIARY LIMIT SWITCH, OVERTEMP. -MANUAL RESET, SPST-(N.C.)
BLWR BLOWER MOTOR RELAY, SPST-(N.O.)
BLWM BLOWER MOTOR
BVSS BLOCKED VENT SHUTOFF SWITCH, SPST - (N.C.)
LEGEND
CAP CAPACITOR
TRAN TRANSFORMER-115VAC/24VAC
(FIELD INSTALLED & SUPPLIED)
CPU MICROPROCESSOR AND CIRCUITRY
DSS DRAFT SAFEGUARD SWITCH
EAC-1 ELECTRON IC AIR CLEA N ER CO N N EC TION (115 VAC 1.5 AM P M AX.)
EAC-2 ELECTRO NIC AIR CLEANER CONNECTION (COMMON)
FL FUSIBLE LINK
FRS FLAME ROLLOUT SW. -MANUAL RESET, SPST-(N.C.)
FSE FLAME PROVING ELECTRODE
FU1 FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED
FU2 FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE
GV GAS VALVE-REDUNDANT OPERATOR S
GVR GAS VALVE RELAY, DPST-(N.O.)
HI/LO BLOWER MOTOR SPEED CHANGE RELAY, SPDT
HSI HOT SUR FA C E IGN ITOR (115 VAC )
HSIR HOT SURFACE IGNITOR RELAY, SPST-(N.O.)
HUM 24VAC HUMIDIFIER CONNECTION (.5 AMP. MAX.)
IDM INDUCED DRAFT MOTOR
IDR INDUCED DRAFT RELAY, SPST-(N.O.)
ILK BLOWER ACCESS PANEL INTERLOCK SW ITCH, SPST-(N.O.)
JB JUNCTION BOX
LED LIGHT-EMITTING DIODE FOR STATUS CODES
LGPS LOW G AS PRESSU RE SW ITCH, SPST-(N.O.)
LS LIMIT SWITCH, AUTO RESET, SPST(N.C.)
OL AUTO-RESET INTERNAL MOTOR OVERLOAD TEMP. SW.
—8—
Page 9
SERVICE
LED CODE
CONTINUOUS OFF - Check for 115VAC at L1 and L2, and 24VAC at
CONTINUOUS ON - Control has 24V power.
RAPID FLASHING - Line voltage (115V) polarity reversed. If twinned, refer to
EACH OF THE FOLLOWING STATUS CODES IS A TWO DIGIT NUMBER WITH THE
FIRST DIGIT DETERMINED BY THE NUMBER OF SHORT FLASHES AND THE
SECOND DIGIT BY THE NUMBER OF LONG FLASHES.
11 NO PREVIOUS CODE - Stored status codes are erased when power (115V or 24V)
to control is interrupted or 48 hours after each fault is cleared.
12 BLOWER ON AFTER POWER UP (115V or 24V) - Blower runs for 90 seconds,
if unit is powered up during a call for heat (R-W closed).
13 LIMIT OR FLAME ROLL-OUT SWITCH LOCKOUT - Auto reset after three hours.
For flame roll-out switch or fuse link, refer to #33.
14 IGNITION LOCKOUT - Control will auto-reset after three hours. Refer to #34.
21 GAS HEATING LOCKOUT - Control will NOT auto reset.
Check for: - Stuck gas valve relay on control or miswire to gas valve circuit.
22 ABNORMAL FLAME-PROVING SIGNAL - Flame is proved while gas valve is
de-energized. Inducer will run until fault is cleared. Check for:
- Stuck-open gas valve or leaky gas valve.
23 PRESSURE SWITCH DID NOT OPEN Check for:
- Obstructed pressure tubing. - Defective pressure switch
24 SECONDARY VOLTAGE FUSE IS OPEN
Check for: - Short circuit in secondary voltage (24V) wiring.
31 PRESSURE, DRAFT SAFEGUARD, AUXILIARY-LIMIT (when used), OR
BLOCKED VENT SHUTOFF (when used) SWITCH DID NOT CLOSE OR
REOPENED - If open longer than five minutes, inducer shuts off for 15 minutes
before retry. Check for:
- Proper vent sizing and condensate pitch - Inadequate Combustion air supply.
or sag. - Low inducer voltage.
- Vent restriction or high winds. - Disconnected or obstructed
- Defective inducer motor or start capacitor. pressure tubing.
- Defective pressure switch or connections. If it opens after trial for ignition period,
blower will come on for 90 second recycle delay.
33 LIMIT OR FLAME ROLL-OUT SWITCH IS OPEN - If open longer than three
minutes,code changes to #13. Check for:
- Defective blower motor or start capacitor. - Dirty filter or restricted duct system.
- Loose blower wheel. - Defective switch or connections.
- Inadequate Combustion air supply Flame Roll-out Switch or fuse link.
- Open Flame Roll-out switch,or fuse link. Manual reset or replace.
34 IGNITION PROVING FAILURE - Control will try three more times before a lockout
#14 occurs. If flame signal lost after trial for ignition period, blower will
come on for 90 second recycle delay. Check for:
- Oxide buildup on flame sensor (clean with fine sandpaper).
- Proper flame sense microamps (.5 microamps D.C. minimum).
- Gas valve turned off. - Manual shut-off valve. - Low inlet gas pressure.
- Green wire MUST be connected to furnace sheet metal.
- Inadequate flame carryover or rough ignition.
SEC-1 and SEC-2.
twinning kit instructions.
COMPONENT TEST
To initiate the component test sequence,shut OFF the room thermostat or disconnect the
"R" thermostat lead. Briefly short the TEST terminal to the ’Com 24V’ terminal. Status
LED will flash code and then turn ON the inducer motor. The inducer motor will run for
the entire component test. The hot surface ignitor, blower motor-heat speed, and blower
motor-cool speed will be turned ON for 10-15 seconds each.
3
6
9
STATUS
8
2
5
1
7
4
TEST
HUM
→ Fig. 13—Service Label
STATUS
(stuck closed).
Com
W
24V
Y
R
320615-102 REV. H
G
A96263
—9—
Page 10
NO
Close circuit breaker and
go back to start.
YES
Close door switch and go to start.Is red LED status light on? Is door switch closed?
NO
NO
Is circuit breaker closed?
NO
YES
YES
Is there 115v going to switch?
NO
Check for continuity in wire from circuit
breaker to furnace.
Replace door switch.Replace control center.
Replace transformer.
NO
Check room thermostat or
interconnecting cable.
YES
Is 24 vac present at W, Y, or G
terminals on the control?
NO
YES
Does control respond to W, Y,
or G 24-vac thermostat signals?
NO
Replace control if it does not
respond to 24-vac signal at W, Y,
or G screw terminals.
Run system through a heating or
cooling cycle to check operation.
Status codes are erased after 48
hrs or whenever power (115v
or 24v) is interrupted.
TROUBLESHOOTING GUIDE
YES
Is there 115v at L1 and L2?
NO
START
YES
Is there 24v at SEC-1 and SEC-2?
YES
Check for correct line voltage
polarity. If units are twinned,
check for proper low-voltage
YES
Is red LED status light blinking
rapidly without a pause?
Check for previous fault by
momentarily shorting the TEST
terminal and the C terminal until
the LED goes out. LED will flash
the status code of any previous
fault or the code No. 11 (1 short
(24v) transformer phasing.
and 1 long flash) if no previous
NO
NO
Is red LED status light blinking
YES
ON/OFF slowly with a
combination of short and long
flashes?
—10—
fault. After the control repeats the
code 3 times, the control will go
through a brief component test
sequence. The inducer will start
and run for the entire component
test. The HSI, blower motor heat
speed, and blower motor cool
speed will run for 10-15 sec each.
Determine status code. The
status code is a 2 digit number
with the first digit determined by
the number of short flashes and
the second digit by the number of
long flashes.
Once status code is determined,
the control will go through a brief
component test sequence. The
inducer will start and run for the
entire component test. The HSI,
YES
Was there a previous fault code
other than No. 11?
blower motor heat speed, and
blower motor cool speed will run
for 10-15 sec each.
Go to section with status code
determined.
Page 11
A98523
Replace control board.
NO
YES
Unplug ignitor harness from control
center and inititate another
component test sequence and check
for 115v between pins 1 and 2 on
the board. Was there 115v present
for the 17 sec period?
Check for continuity in the harness
and ignitor. Replace defective
component.
Check connections. If OK, replace
control board.
NO
Reconnect the R thermostat lead
and set thermostat to call for heat.
Connect voltmeter across gas valve
connections. Does gas valve
Check that all gas valves are turned
on. Replace valve.
NO
YES
receive 24v?
YES
Does gas valve open and allow gas
to flow?
NO
rough ignition.
• Low inlet gas pressure.
• Inadequate flame carryover on
Check for:
NO
YES
Do main burners ignite?
Repeat call for heat and check flame
sensor current during trial for ignition
NO
YES
Do main burners stay on?
Allow blower to come on and repeat
test to check for intermittent
Check connections including equipment
ground and retry. Green wire must be
connected to furnace sheet metal. If
current is near typical value and control
will not stay on, replace control board.
YES
period. Is the dc microamperes
below 0.5?
operation.
Clean flame sensor with fine
NO
Replace electrode.
YES
sandpaper and recheck current.
Current is nominally 4.0 to 6.0
microamps DC.
Is current near typical value?
NO
Replace control board.
YES
Will main burner ignite and stay on?
Fixed.
SAFEGUARD (WHEN USED),
OR AUXILIARY LIMIT (WHEN
USED) SWITCH WILL NOT
CLOSE OR REOPEN - If open
longer than 5 minutes, inducer
31 PRESSURE, DRAFT
are erased after 48 hrs or
whenever power (115V or 24V)
is interrupted. Run system
through a heating or cooling
11 NO PREVIOUS FAULT - Faults
sag.
shuts off for 15 minutes before
retry.
Check for:
• Proper vent sizing or pitch or
cycle to recheck system.
UP (115V OR 24V) - Normal
12 BLOWER ON AFTER POWER
connections. If it opens after
trial for igniton period, blower
will come on for 90 sec
recycle delay.
Inadequate combustion air
• Vent restrictions or high winds.
• Defective inducer motor.
• Low-line voltage (115v).
• Motor start capacitor.
• Low inlet gas pressure.
• Defective pressure switch or
operation. Blower will run for 90
sec when furnace power is
interrupted during a call for heat
and R-W closes.
SWITCH LOCKOUT - Limit
13 LIMIT OR FLAME ROLLOUT
(for draft safeguard and
•
switch was open longer than
3 minutes. Auto-reset will occur
after 3 hrs. Flame rollout switch
requires manual reset.
auxiliary limit switches only).
SWITCH IS OPEN - If limit
switch is open longer than 3
minutes, code changes to No. 13.
33 LIMIT OR FLAME ROLLOUT
See No. 33
failed to ignite gas and prove
flame in 4 attempts. Control will
14 IGNITION LOCKOUT - System
manual reset.•Dirty or restrictive filter.
Check for:
• Blower motor failure.
• Motor start capacitor.
• Open flame rollout switch,
auto-reset in 3 hrs.
See No. 34
21 GAS HEATING LOCKOUT -
Defective limit switch or
connections.
Inadequate combustion air
supply (flame rollout
switch only).
Turn off power and wait 5
minutes to retry.
Check for:
Loose blower wheel.
Restricted duct system.•
•
•
•
34 IGNITION PROVING FAILURE -
wire.
on control.
• Miswire or short to gas valve
• Stuck closed gas valve relay
If flame is not sensed during the
trial for ignition period, the control
will repeat the ignition sequence
3 more times before going into
lockout, No. 14.
If flame signal is lost after trial for
ignition period, blower will come
on for 90 sec recycle delay.
Check for the following items first
before proceding to the next step.
• Gas valve turned off.
or leak.
SIGNAL - Flame was sensed
while gas valve was
de-energized. Inducer will run
22 ABNORMAL FLAME PROVING
• Defective control board.
until fault is cleared.
Check for:
• Stuck open gas valve solenoid
23 PRESSURE SWITCH WILL
NO
to furnace sheet metal.
• Manual shut-off valve.
• Green wire must be connected
To determine whether the
problem is in the gas valve,
igniter, or flame sensor, the
system can be operated in the
component test mode to check
out the ignitor. First, remove the
R thermostat connection from the
pressure tubing.
• Defective pressure switch.
NOT OPEN - Check for:
• Disconnected or obstructed
including thermostat leads
OPEN - Check for:
• Short in low-voltage wiring
24 LOW-VOLTAGE FUSE IS
YES
control board and initiate the
component test sequence. Does
the ignitor glow orange/white hot
by the end of the 17 sec warm-up
period?
shorting to ductwork or
furnace cabinet. Disconnect
thermostat leads to isolate
short circuit.
—11—
Page 12
SERVICE TRAINING
Packaged Service Training programs are an excellent way to increase your
knowledge of the equipment discussed in this manual, including:
• Unit Familiarization • Maintenance
• Installation Overview • Operating Sequence
A large selection of product, theory, and skills programs is available, using popular
video-based formats and materials. All include video and/or slides, plus companion
book.
Classroom Service Training plus "hands-on" the products in our labs can mean
increased confidence that really pays dividends in faster troubleshooting, fewer
callbacks. Course descriptions and schedules are in our catalog.
CALL FOR FREE CATALOG 1-800-962-9212
[ ] Packaged Service Training [ ] Classroom Service Training
A94328
© 1998 Bryant Heating & Cooling Systems 7310 W. Morris St. Indianapolis, IN 46231
—12—
Printed in U.S.A. sp0454 Catalog No. 5337-601
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