Sterling RT - Manual (Page 25)

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Chart 6 - Troubleshooting continued
POSSIBLE CAUSES
1. Thermostat malfunction.
2. Heater runs continuously.
a. Improper thermostat or
transformer wiring at gas
valve.
b. Short circuit.
c. Defective or sticking gas
valve.
d. Excessive gas supply
pressure.
1. Lack of power at unit.
2. Defective power venter relay.
3. Defective motor.
4. Thermostat not calling for heat.
5. Defective limit switch.
1. Power venter wheel loose.
2. Bearings dry.
3. Power venter wheel blade
dirty.
4. Power venter wheel rubbing
housing.
1. Loose wiring.
2. Defective motor overload
protector or defective motor.
3. Defective power venter relay.
1. Improperly wired fan relay.
2. Defective fan relay.
*Indicates Power Vent Units Only
SYMPTOMS
N. Too much heat.
* P. Power venter motor will not
start.
* Q. Noisy power venter.
* R. Power venter will not run.
* S. Power venter motor will not
stop.
CORRECTIVE ACTION
1. Replace thermostat.
2.
a. Check wiring per diagrams.
b. Check operation at valve.
Look for short and correct
(such as staples piercing
thermostat wiring).
c. Replace gas valve.
d. Refer to operation.
1. Replace fuse or turn on power.
2. Replace.
3. Replace.
4. Turn up thermostat.
5. Replace limit switch.
1. Tighten or replace.
2. Oil bearings on power venter
motor.
3. Clean power venter wheel
blade.
4. Realign power venter wheel.
1. Check and tighten all wiring
connections per diagrams.
2. Replace motor.
3. Check for 24V across 1 & 3
terminals on fan relay. If 24V
is present, jumper terminals
numbered 2 and 4. If motor
runs, relay is defective and
must be replaced. If 24V is not
present check wiring diagrams.
1. Check all wiring.
2. Replace fan relay.