General Troubleshooting
PROBLEM PROBABLE CAUSE
REMEDY
Venter
motor will
not start
1. No power to unit.
1. Turn on power; check supply fuses or main circuit breaker. Turn
on built-in disconnect switch; replace switch if not operating.
2. No 24 volt power to integrated circuit
board.
2. Turn up thermostat; check control transformer output.
3. Integrated circuit board fuse blown.
3. Correct cause. Replace fuse (type ATC or ATO, 32VDC, 3A).
4. No power to venter motor.
4. Tighten connections at circuit board and/or motor terminals.
5. Integrated circuit board defective.
5. Replace integrated circuit board.
6. Defective venter motor.
6. Replace venter motor. See Paragraph 12.2.6.
Burner will
not light
1. Manual valve not open.
1. Open manual valve.
2. Air in the gas line.
2. Bleed gas line (initial startup only).
3. Gas pressure too high or too low.
3. Supply pressure should be 5" - 14" w.c. for natural gas or 11"
- 14" w.c. for propane gas.
4. No Spark:
4.
a) Loose wire connections.
a) Be certain all wire connections are solid.
b) Transformer failure.
b) Be sure 24 volts is available.
c) Incorrect spark gap.
c) Maintain spark gap at 1/8" (3.2mm).
d) Spark cable shorted to ground.
d) Replace worn or grounded spark cable.
e) Spark electrode shorted to ground.
e) Replace if ceramic spark electrode is cracked or grounded.
f) Burner not grounded.
f) Make certain integrated circuit board is grounded to ignitor.
g) Circuit board not grounded.
g) Make certain integrated circuit board is grounded to furnace
chassis.
h) Unit not properly grounded.
h) Make certain unit is properly field grounded to earth ground and
properly phased (L1 to hot lead L2 to neutral).
i) Integrated circuit board fuse blown.
i) Correct cause. Replace fuse (type ATC or ATO, 32VDC, 3A).
j) Faulty integrated circuit board.
j) If 24 volt is available to the integrated circuit board and all other
causes have been eliminated, replace board.
5. Lockout device interrupting control
circuit by above causes.
5. Reset lockout by interrupting control at the thermostat or main
power.
6. Interlock door switch open.
6. Close access door or replace switch.
7. Combustion air proving switch not
closing
7.
a) Make sure unit is properly vented.
b) Remove obstructions from vent.
c) Replace faulty tubing to pressure switch.
8. Faulty combustion air proving switch.
8. Replace combustion air proving switch.
9. Main valve not operating.
9.
a) Defective valve.
a) If 24 volt is measured at the valve connections and valve remains
closed, replace valve.
b) Loose wire connections
b) Check and tighten all wiring connections.
10. Integrated circuit board does not power
main valve.
10.
a) Loose wire connections.
a) Check and tighten all wiring connections.
b) Flame sensor grounded.
b) Be certain flame sensor lead is not grounded or insulation or
ceramic is not cracked. Replace as required.
c) Incorrect gas pressure.
c) Supply pressure should be 5" - 14" w.c. for natural gas or 11"
- 14" w.c. for propane gas.
d) Cracked ceramic at sensor.
d) Replace sensor.
11. Faulty time delay relay.
11. Replace time delay relay.
12.3 Troubleshooting (cont’d)
12. Maintenance and Service (cont’d)
Form I-UEAS, Page 48
