
33
Troubleshooting
24 Vac across
terminals W1 and X?
Heat Switch (S3) Off
(Turn Heat Switch S3 On)
Heat Switch Not Wired
(Wire Heat Switch S3)
115 Vac across
terminals 102 and 101?
Secondary Fuses (FU7) Blown
(Replace Fuses)
Main Transformer (TR1) Defective
(Replace Transformer TR1)
115 Vac across
terminals 105 and 101?
High/Low Gas Pressure Switch(s) (PS1, PS3) Tripped
(Correct gas pressure and reset)
(Reference Direct Gas Start-Up Step #2)
115 Vac across
terminals 104 and 101?
High Limit (HLC1) Tripped
(Reset/Replace High Limit HLC1)
(Check on cause of control loss)
Continuity across
terminals 105 and 108?
115 Vac across
terminals 103 and 101?
Inlet Air Senor (TS1) Holding
(Adjust TS1 setting -- Reference blower start-up step 6)
Heat Relay (R2) Defective
(Replace Heat Relay R2)
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Airflow Switch (PS2) Holding for Proper Airflow
(Correct airflow across burner)
(Reference Direct Gas Start-Up Step #3)
Yes
At this time the heater should attempt to light
Heater Does Not Operate
Does not attempt to light (No visible spark)
Troubleshooting