Heater Does Not Operate (Pilot Ignition); Maintenance - Greenheck VSU Installation, Operation And Maintenance Manual

Troubleshooting

Heater Does Not Operate (Pilot Ignition)

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
115 VAC between
terminals 106 and 101?
Yes
Continuity between
terminals 107 and 108?
Yes
26 Model VSU Make-Up Air
No
No
No
(Optional) inlet air sensor (TS4) holding.
Reference: Start-Up - Blower, Set-Up Optional Components, pg. 15
The power light on the flame safeguard should
blink approximately every 5 seconds as it
No
No
(Optional) high/low gas pressure switch(es)
Reference: Start-Up - Direct Gas, Check the Pilot Gas Pressure, pg. 15
No
Airflow switch (PS2) holding for proper airflow.
Check the Optional High and Low Gas Pressure Switches, pg. 15
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.
Main transformer (TR4) defective.
Replace transformer.
Adjust TS4 setting.
Heat relay (RH) defective.
Replace heat relay (RH).
performs a self-diagnostics check.
High limit (HLC1) tripped.
Reset or replace high limit (HLC1).
Check on cause of control loss.
(PS3 and PS4) tripped.
Correct gas pressure and reset.
Correct airflow across burner.
Reference: Start-Up - Direct Gas,
®