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 in blower compartment door.
3.If
4.After replacing any component, verify correct operating sequence.
START
Turn thermostat OFF.
On furnace control, note current
settings for setup switches 1
Cycle |
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off for 3 sec, then on. |
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Continuous LED? | No | |
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Yes |
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Set thermostat to call for heat. |
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Set FAN to AUTO mode. |
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Draft inducer motor starts. | No | |
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Yes | No | |
Is Code 22 displayed? | ||
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Yes |
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Flame present when not normal. |
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Replace gas valve. |
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Yes |
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Ignitor warms up and glows | No | |
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orange/yellow; |
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Yes |
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Main burners ignite. | No | |
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Yes |
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Main burners stay on. | No | |
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Yes |
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Indoor blower motor starts on | No |
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heating speed after |
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| Yes |
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| No |
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Furnace runs until call for |
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heat ends. |
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| Yes |
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Turn thermostat to OFF; gas valve | No |
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shuts off burners; |
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post purge. |
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| Yes |
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| No |
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Indoor blower motor stops after |
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90, 135, 180, or 225 sec. |
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Yes
Heating sequence of operation complete. Remove blower door, move setup switch 1
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
If Code 45 is displayed, replace control.
Is indoor blower on ?
No
24v should be present across Com and W at furnace control. If not, check for:
1.Open thermostat.
2.Open
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
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 draft safeguard switch (DSS) – Code 32.
4.Open auxiliary switch (ALS)(downflow only) – Code 32.
5.Check all
115v should be present at the ignitor. If so, replace the ignitor; if not, check
LPS, DSS, or ALS open while HPS if closed
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 or switch in the OPEN or ON position? 24v should be present across the gas valve terminals C and M/P (and C and HI for
If 24v are present, and main gas does not flow:
1.Supply pressure between 4.5- and
2.If supply pressure is between 4.5- and
Check ignitor position.
Check burner carryover gap.
Check gas supply pressure
Check manifold pressure (1.3- to
Check for proper orifice size.
Is Code 31
Check polarity of
Check ground continutity from
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
If not, check for:
1.Satisfied thermostat.
2.Open inlet gas pressure switch (when used).
3.Open pressure switch (LPS) – Code 32.
4.Open draft safeguard switch (DSS) – Code 32.
5.Open auxilliary limit (ALS)(downflow only) – Code 32.
6.Open
7.Open limit switch (LS) – Code 13 or 33.
8.Open flame rollout switch (FRS) – Code 13 or 33.
9.Check
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 or switch to the OFF position. Replace gas valve.
!WARNING
ELECTRICAL SHOCK HAZARD
ONLY QUALIFIED AND TRAINED
SERVICE PERSONNEL SHOULD
PERFORM THIS PROCEDURE
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| 24v should be present across R |
| Yes | and Com. If not, check for: |
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| 1. Open flame rollout switch | |
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| (FRS) – Code 33. |
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2.Open limit switch (LS) –
Code 33.
3.Check all
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| No |
No |
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Replace control only if all checks | ||
| are OK. | |
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No |
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Replace control only if Code 45 is | ||
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| displayed, or if all checks are OK. |
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No | Replace control only if Code 45 is |
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| displayed, or if all checks are OK. |
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No | Replace control if Code 45 is dis- |
played, or if all checks are OK. | |
| Clean flame sensor if microamps |
| are below nominal. |
No |
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Replace control only if Code 45 is | |
| displayed, or if all checks are OK. |
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No | Replace control only if Code 45 is |
| displayed, or if all checks are OK. |
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No | Replace control only if Code 45 is |
| displayed, or if all checks are OK. |
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position and repeat process to check
24v should be present across R and Com. If not, check for: | No | Replace control only if Code 45 is | ||
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| displayed, or if all checks are OK. | ||
1. | Open limit switch (LS) – Code 13 or 33. |
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2. | Open flame rollout switch (FRS) – Code 13 or 33. |
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24v should not be present across R and G. If so, set thermostat |
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FAN to AUTO mode. |
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