Greenheck DGX Installation, Operation And Maintenance Manual page 33

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