Troubleshooting - Bryant 352MAV Service And Maintenance Procedures Manual

NOTES:
1. Refer to information label on blower compartment door
for procedure for use of LED status codes and problem
solving suggestions.
2. LED indicator is viewed through window on blower
compartment door.
3. If 115-vac power is energized or interrupted during a
call for heat, the indoor blower will run for 90 sec before
a gas heating cycle begins – Code 12.
4. After replacing any component, verify correct operating
sequence.
START
Turn thermostat OFF.
On furnace control, note current
settings for setup switches 1 (SW-1)
and 2 (SW-2) then set SW-1 to OFF
and SW-2 to ON.
Cycle 115-v power
off for 3 sec, then on.
No
Continuous LED?
Yes
Set thermostat to call for heat.
Set FAN switch to AUTO.
No
Draft inducer motor starts.
Yes
No
Is Code 22 displayed?
Yes
Flame present when not normal.
Replace gas valve.
15-sec inducer pre-purge.
Yes
No
Ignitor warms up and glows
orange/yellow; 17-sec warm-up.
Yes
No
Main burners ignite.
Yes
No
Main burners stay on.
Yes
Indoor blower motor starts on
No
heating speed after 60-sec
warm-up period.
Yes
No
Furnace runs until call for
heat ends.
Yes
Turn thermostat to OFF; gas valve
No
shuts off burners; 15-sec inducer
post purge.
Yes
No
Indoor blower motor stops after
90, 135, 180, or 225 sec.
Yes
Heating sequence of operation
complete. Remove blower door,
move setup switch 1 (SW-1) to ON
position and repeat process to check
high-fire operation. (When finished
return SW-1 and SW-2 to original
desired settings.)

TROUBLESHOOTING

GUIDE
If LED is flashing rapidly, check line voltage polarity.
If Code 24 is displayed, check for blown fuse.
If LED is OFF, check line voltage and 24-v transformer.
If Code 45 is displayed, replace control.
Is indoor blower on ?
No
24v should be present across C and W. If not, check for:
1. Open thermostat.
2. Open 24-v fuse (FU1) – Code 24.
3. Failed transformer.
If Code 23 is displayed, the pressure switch(es) is stuck closed.
Replace switch and/or check pressure tube for blockage.
System malfunction – Code 21.
115v should be present at the inducer motor. If so, replace inducer
motor. If not, check 115-v wiring.
If Code 32 is displayed check for:
1. Open gas inlet pressure switch (when used).
2. Open pressure switch (LPS) and/or tube – Code 32.
3. Open Propane low gas pressure switch (LGPS) – Code 32.
4. Check all low-voltage wiring connections.
115v should be present at the ignitor. If so, replace the ignitor; if not,
check 115-vac wiring to ignitor.
LPS or LGPS open while HPS is closed (high-gas-heat only) –
Code 43.
Control will attempt to light burners 4 times (approximately 1 minute
between attempts – Code 34). Voltage is present at the gas valve for 7
sec during each ignition trial. System will lockout after 4 attempts.
Is the gas valve control knob in the OPEN or ON position?
24v should be present across the gas valve terminals C and M
(and C and HI for high-fire test) during the 7 sec ignition trial. If
not, check all low-voltage wiring connections to valve.
If 24v are present, and main gas does not flow:
1. Supply pressure > 13.6-in. wc.
2. Replace gas valve.
Check ignitor position.
Check burner carryover gap.
Check gas supply pressure (4.5-in. wc minimum).
Check manifold pressure (1.3- to 1.7-in. wc for low-fire; 3.2- to
3.8-in. wc for high fire).
Check for proper orifice size.
Is Code 31 (high-gas-heat only), 32, 33, or 34 displayed? Check
code information label to diagnose.
Check polarity of 115-v power at J-box and control. Twinned
furnace polarities must match – rapid flashing LED.
Check ground continutity from J-box to control.
Check flame sensor microamps (4.0 nominal; 0.5 minimum for
control to recognize flame).
115v should be present at the blower motor. If so, check capacitor.
If capacitor is OK, replace blower motor. If 115v are not present at
the blower motor, check all 115-v wiring to motor.
If not, check for:
1. Satisfied thermostat.
2. Open inlet gas pressure switch (when used).
3. Open propane low gas pressure switch (LGPS) – Code 32.
4. Open auxilliary limit (ALS)(downflow/horizontal only) – Code 32.
5. Open 24-v fuse (FU1) – Code 24.
6. Open limit switch (LS) – Code 13 or 33.
7. Open flame rollout switch (FRS) – Code 13 or 33.
8. Check 115-v line voltage – LED off.
Check for sources of electrical noise interference (electronic air
cleaners, nearby TV, or radio antennas).
If inducer and burners continue to operate, check for 24v at the
gas valve. If 24v are present, verify that the thermostat is open
across R and W. If no voltage is present, turn the gas valve control
knob to the OFF position. Replace gas valve.
24v should be present across R and C. If not, check for:
1. Open limit switch (LS) – Code 13 or 33.
2. Open flame rollout switch (FRS) – Code 13 or 33.
24v should not be present across R and G. If so, turn thermostat
FAN switch to AUTO.
—13—
WARNING
!
ELECTRICAL SHOCK HAZARD
ONLY QUALIFIED AND TRAINED
SERVICE PERSONNEL SHOULD
PERFORM THIS PROCEDURE
24v should be present across R
and C. If not, check for:
Yes
1. Open flame rollout switch
(FRS) – Code 33.
2. Open limit switch (LS) –
Code 33.
3. Check all low-voltage wiring
connections.
No
No
Replace control only if all checks
are OK.
No
Replace control only if Code 45 is
displayed, or if all checks are OK.
No
Replace control only if Code 45 is
displayed, or if all checks are OK.
Replace control if Code 45 is dis-
No
played, or if all checks are OK.
Clean flame sensor if microamps
are below nominal.
No
Replace control only if Code 45 is
displayed, or if all checks are OK.
No
Replace control only if Code 45 is
displayed, or if all checks are OK.
No
Replace control only if Code 45 is
displayed, or if all checks are OK.
No
Replace control only if Code 45 is
displayed, or if all checks are OK.
A01056