There are five major electrical parts involved in the heating process:
1. Hi limit thermostat
2. Cycling thermostat
3. Igniter
4. Flame sensor
5. Gas valve coils
How to find out which part causing the problem?
Pretty simple: all of these parts have to be tested for continuity in the above sequence.
The following article on our forum will explain in detail how to run a continuity test using either an analog meter or a digital meter -
How To Check Continuity With Ohmmeter
If any of them is open – it has to be replaced.
Gas valve coils also could be tested by resistance. There are two coils – one with three terminals and one with two terminals.
1. Coil with two terminals should have 1220 ± 50 Ohms
2. Coil with three terminals if held with terminals in upper position:
a) across the left and the middle terminals – 1365 ± 25 Ohms
b) across the left and the right terminals – 560 ± 25 Ohms
- The part number for the hi limit thermostat is
AP275754
- The part number for the igniter is
AP3464835
- The part number for the flame sensor is
AP2910747
- The part number for the gas valve coils kit is
AP3094251
- The part number for the cycling thermostat is
AP276896
The first four parts are located on or around the gas valve, the cycling thermostat is located on the blower cover.
Good luck.
Gene.