Trane TR250 Service & Installation Manual page 54

54
TROUBLESHOOTING
Figure 28:
Code Fault
Open FC1 and/
or FC2 Fuses.
Open FC3 and/
or F1 Fuses
None
Open FC4
Fuse.
Diagnosis Step
1. Verify that 120VAC
Voltage Selector Plug
is not installed with a
240VAC fi eld power
supply.
2. Check for faulty
Transformer wiring.
3. Defective Transformer
1. Check for faulty Gas
Valve wiring.
2. Verify that Gas Valve is
not defective.
3. Check for faulty
Control Module wiring.
4. Control Module is
defective.
1. Check for faulty Igniter
wiring.
2. Check for faulty
Blower wiring.
3. Check for defective
Igniter.
4. Check for defective
Blower.
5. Control Module is
defective.
Remedy
Check that proper Voltage Selector Plug is installed. If OK,
proceed to step 2.
If 120VAC plug is installed and fi eld supply voltage is
240VAC, FC1 and FC2 fuses will have to be opened. Install
the correct Voltage Selector Plug and new FC1 and FC2 fuses.
Inspect Transformer wiring. Ensure insulation on wiring is not
worn. If OK, proceed to step 3.
Replace Transformer.
Inspect Gas Valve wiring. Ensure insulation on wiring is not
worn. If OK, proceed to step 2.
Mesure for resistance across Gas Valve terminals and between
each terminal and ground. If short exists, replace Gas Valve.
If OK, proceed to step 3.
Inspect Control Module wiring. Ensure insulation on wiring is
not worn. If OK proceed to step 4.
Replace Control Module.
Inspect Igniter wiring. Ensure insulation on wiring is not
worn. If OK, proceed to step 2.
Inspect Blower wiring. Ensure insulation on wiring is not
worn. If OK, proceed to step 3.
Disconnect Igniter plug from Control Module. Measure
resistance across Igniter. Resistance should be 10.9-19.7 ohms
at at 77°F. If out of this range, replace igniter. If OK, proceed
to step 4
Disconnect Blower plug from Control Module. Measure
resistance across Blower windings. Winding resistance across
lead should be in the following range: Red-to-White: 4 to
5 ohms. If measured values vary substantially from these
values, blower is defective. Replace. Otherwise
step 5.
Replace Control Module.
proceed to