Bryant 393AAV User Manual

service and

393AAV

maintenance procedures

GAS-FIRED
INDUCED-COMBUSTION FURNACE

NOTE: Read the entire instruction manual before performing any
service or maintenance.

These procedures are for size 66,000 through 154,000 Btuh input
units.

Index Page

SAFETY CONSIDERATIONS.....................................................1

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS

PROCEDURE...........................................................................2

CARE AND MAINTENANCE..................................................2-8

Air Filter Arrangement.............................................................2

Blower Motor and Wheel......................................................2-3

Cleaning Heat Exchanger......................................................3-5

Unit Wiring Diagram................................................................7

Electrical Controls and Wiring .............................................5-8

Troubleshooting...................................................................8-11

Service Label ............................................................................9

Troubleshooting Guide......................................................10-11

Series A

Cancels: SP04-52 SP04-58

ama

®

REGISTERED QUALITY SYSTEM

8-99

CANADIAN GAS ASSOCIATION

APPROVED

R

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
54-1999/ANSI Z223.1-1999 and the Installation Standards, Warm
Air Heating and Air Conditioning Systems (NFPA 90B)
ANSI/NFPA 90B. In Canada, refer to the CAN/CGA-B149.1- and
.2-M95 National Standard of Canada, 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, CAUTION,
and NOTE. 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.

A94085

Fig. 1—Model 393AAV Upflow Furnace

WARNING: The ability to properly perform mainte-

nance 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.

CAUTION: Label all wires prior to disconnection when
servicing controls. Wiring errors can cause improper and
dangerous operation.

—1—

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.

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 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 for filter size information.

TABLE 1—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

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.

7. An ESD service kit (available from commercial sources)
may also be used to prevent ESD damage.

CARE AND MAINTENANCE

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 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.

Each furnace requires 1 or 2 filters which are installed in the
blower compartment. (See Fig. 2.) To remove filters for
cleaning or replacement, proceed as follows:

1. Disconnect electrical power before removing access doors.

2. Remove blower and control access doors.

3. Release filter retainer from clip at front of furnace casing.
(See Fig. 2.) For side return, clips may be used on either or
both sides of the furnace.

4. Slide filter(s) out.

5. Furnaces are equipped with permanent, washable filters.
Clean filters with tap water. Spray water through filter in
opposite direction of airflow.

6. Rinse and let dry. Oiling or coating of filter is NOT
recommended or required.

7. Reinstall filter(s).

8. Replace blower and control access doors.

9. Restore electrical power to furnace.

B. Blower Motor and Wheel

The following steps should be performed by a qualified service
technician.

—2—

FLUE
COLLAR

MOUNTING

SCREWS

RELIEF

BOX

GAS

VALVE

CONTROL

HUM

C

24V

OM

GRYW

To ensure long life, economy, and high efficiency, clean accumu-

Fig. 2—Model 393AAV Upflow Furnace

BLOCKED
VENT
SAFEGUARD

PRESSURE
SWITCH

FLUE
COLLECTOR
BOX

FILTER
RETAINER

WASHABLE
FILTER

A99284

lated dirt and grease from blower wheel and motor annually.
The inducer and blower motors are pre-lubricated and require no
additional lubrication. These motors can be identified by the
absence of oil ports on each end of the motor.
Clean blower motor and wheel as follows:

1. Turn off electrical supply to furnace.

2. Remove control and blower access doors.

3. Disconnect blower leads from furnace control. Note wire
color and location for reassembly.

All other factory wires can be left connected, but field
thermostat connections may need to be disconnected de­pending on their length and routing.

4. Remove 2 screws securing control and transformer support
to furnace.

5. Hang control and transformer support to side of furnace
casing.

6. Remove screws holding blower assembly to blower deck
and slide blower assembly out of furnace.

7. Clean blower wheel and motor using a vacuum 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.

8. If greasy residue is present on blower wheel, remove wheel
from the blower housing and wash it with an appropriate
degreaser. To remove wheel:
a. Mark blower wheel location on shaft before disassembly

to ensure proper reassembly.

b. Loosen setscrew holding blower wheel on motor shaft.

NOTE: Mark blower mounting arms, motor, and blower housing
so motor and each arm is positioned at the same location during
reassembly.

c. Mark blower wheel orientation and cutoff plate location

to ensure proper reassembly.

d. Remove screws securing cutoff plate and remove cutoff

plate from housing.

e. Remove bolts holding motor and motor mounts to

blower housing and slide motor and mounts out of
housing. Disconnect capacitor and ground wire attached
to blower housing before removing motor. Motor mount
belly band need not be removed unless motor is to be
replaced.

f. Remove blower wheel from housing.

CAUTION: The blower wheel should not be dropped or
bent as balance will be affected.

9. Reassemble motor and blower by reversing items 9a
through 9f. Be sure to reattach ground wire.

10. Reinstall blower assembly in furnace.

11. Reinstall control and transformer support assembly in
furnace.

12. Reconnect blower leads to furnace control.
Refer to furnace wiring diagram and connect thermostat

leads if previously disconnected. (See Fig. 7.)

NOTE: Refer to Table 2 for motor speed lead relocation if leads
were not identified before disconnection.

→TABLE 2—SPEED SELECTOR

COLOR SPEED

Black High Cool

Yellow (When

present)

Blue Medium-Low Heat

Red Low Spare

White Common L2/COM

Medium-High Spare

FACTORY-

ATTACHED TO

CAUTION: Heating air speed selection MUST be ad-

justed to provide proper air temperature rise as specified
on the rating plate. Failure to adjust the heating speed
may shorten heat exchanger life.

13. Turn on electrical supply. Manually close blower access
door switch. Use a piece of tape to hold switch closed.
Check for proper rotation and speed changes between
heating and cooling by jumpering R to W and then R to Y
on furnace control thermostat terminals.

WARNING: Blower access door switch opens 115-v
power to furnace control. 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 electrical shock, personal injury, or
death.

NOTE: If thermostat terminals are jumpered before blower ac­cess door switch is closed, blower will run for 90 sec before
beginning a heating or cooling cycle.

14. If furnace is operating properly, REMOVE TAPE TO
RELEASE BLOWER ACCESS DOOR SWITCH, replace
blower access door.

→

C. Cleaning Heat Exchanger

The following steps should be performed by a qualified service
technician.

NOTE: If the heat exchangers get a heavy accumulation of soot
and carbon, they should be replaced rather than trying to clean
them thoroughly due to their intricate design. A build-up of soot
and carbon indicates that a problem exists which needs to be
corrected, such as improper adjustment of manifold pressure,
insufficient or poor quality combustion air, incorrect size, or
damaged manifold orifice(s), improper gas, or a restricted heat
exchanger. Action must be taken to correct the problem.

—3—

If it becomes necessary to clean the heat exchanger because of dust
or corrosion, proceed as follows:

1. Turn gas and electrical power to furnace OFF.

2. Remove control access door.

3. Disconnect vent connector from furnace flue collar.

4. Remove 2 screws that secure relief box. (See Fig. 2.)

5. Disconnect wires to the following components. Mark wires
to aid in reconnection of:

a. Blocked vent safeguard switch.
b. Inducer motor.
c. Pressure switch.
d. Limit overtemperature switch(es).
e. Gas valve.
f. Hot surface igniter.
g. Flame-sensing electrode.
h. Flame rollout switch(es), if applicable.

6. Remove complete inducer assembly and relief box from
furnace.

7. Remove 8 screws that secure flue collector box to center
panel. Be careful not to damage collector box.

8. Remove burner assembly and cell inlet plates. IMPOR­TANT: Replace screws in center panel and cells before
cleaning.

NOTE: Be careful when removing burner assembly to avoid
breaking igniter. See Fig. 4 for correct igniter location.

9. Using field-provided small wire brush, steel spring cable,
reversible electric drill, and vacuum cleaner, clean cells as
follows:

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).

(2.) Use 1/4-in. diameter wire brush (commonly known

as 25-caliber rifle cleaning brush).

NOTE: The materials needed in (1.) and (2.) can usually be
purchased at local hardware stores.

(3.) Insert twisted wire end of brush into end of 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

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. 3.)

(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.) 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.

(5.) Repeat foregoing procedures until each cell in

furnace has been cleaned.

(6.) Using vacuum cleaner, remove residue from each

cell.

(7.) Using vacuum cleaner with soft brush attachment,

clean burner assembly.

(8.) Reinstall cell inlet plates and burner assembly. Care

must be exercised to center burners in cell openings.

10. Clean flame sensor with fine steelwool.

11. Remove old sealant from center panel and collector box
flange and apply new sealant to collector box flange and
reinstall on center panel, making sure all 8 screws are
secure.

NOTE: A releasing agent such as PAM cooking spray or equiva­lent (must not contain corn or canola oil, aromatic or halogenated
hydrocarbons or inadequate seal may occur) and RTV sealant
(G.E. 162, 6702, or Dow-Corning 738) are needed before starting
installation. DO NOT substitute any other type of RTV sealant.
G.E. 162 (P771-9003) is available through RCD in 3-oz. tubes.

12. Reinstall relief box and inducer assembly.

NOTE: If inducer assembly gasket is damaged, use RTV sealant
to seal inducer assembly to collector box.

NOTE: A releasing agent such as PAM cooking spray or equiva­lent (must not contain corn or canola oil, aromatic or halogenated
hydrocarbons or inadequate seal may occur) and RTV sealant
(G.E. 162, 6702, or Dow-Corning 738) are needed before starting
installation. DO NOT substitute any other type of RTV sealant.
G.E. 162 (P771-9003) is available through RCD in 3-oz. tubes.

13. Reconnect wires to the following components.
a. Blocked vent safeguard switch.

A91252

Fig. 3—Cleaning Heat Exchanger Cell

b. Inducer motor.
c. Pressure switch.
d. Limit overtemperature switch(es).
e. Gas valve.
f. Hot surface igniter.
g. Flame-sensing electrode.
h. Flame rollout switch(es), if applicable.

14. Reinstall vent connector on furnace flue collar. After fully
assembling vent connector to furnace flue collar, securely
fasten vent connector to flue collar with 2 field-supplied,
corrosion-resistant, sheet metal screws located 180° apart
and midway up the collar.

15. Turn electrical power and gas to ON.

16. Set thermostat and check furnace for proper operation.

17. Verify blower airflow and speed changes between heating
and cooling.

18. Check for gas leaks.

—4—