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Troubleshooting
Heater Does Not Operate
Does not attempt to light (No visible spark)
24 VAC between
terminals W1 and X?
Yes
115 VAC between
terminals 102 and 101?
Yes
115 VAC between
terminals 103 and 101?
Yes
115 VAC between
terminals 104 and 101?
Yes
Continuity between
terminals 107 and 108?
Yes
® ® ® ® ®
No
No
Main Transformer (TR4) Defective
No
(Adjust TS setting — Reference Blower Start-Up Step #6)
The power light on the flame safeguard should
blink approximately every 5 seconds as it
performs a self-diagnostics check.
No
No
Airflow Switch (PS) Holding for Proper Airflow
(Reference Direct Gas Start-Up Step #3)
At this time the heater should attempt to light.
(The pilot light on the flame safeguard should illuminate).
Heat Switch (S4) Off
(Turn Heat Switch (S4) On)
Heat Switch Not Wired
(Wire Heat Switch (S4))
Primary Fuses Blown
(Replace Fuses)
(Replace Transformer)
Inlet Air Sensor (TS) Holding
Heat Relay (RH) Defective
(Replace Heat Relay (RH))
High Limit (HLC) Tripped
(Reset/Replace High Limit (HLC))
(Check on cause of control loss)
(Correct airflow across burner)
15
Model VSU Make-Up Air
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