53
Figure 28:
TROUBLESHOOTING
Code
Fault
Diagnosis Step
Remedy
None
Heater will not
power up.
1. Check for Low & High
Voltage Output from Fuse
Board
Disconnect plug from P5 connector from Fuse Board.
Measure for 24VAC between pins of receptacle on Fuse Board.
Reconnect plug. Disconnect plug from P6 of Fuse Board.
Measure for 120VAC between pin 3 and 5 of receptacle on
Fuse Board. Reconnect plug. If OK, proceed to section titled
‘‘Low voltage circuit fault’’. Otherwise, proceed to step 2.
2. Ensure fi eld power
supply to heater is turned
on.
Measure for fi eld supply voltage across terminals of TB1
terminal block on Fuse Board. If OK, proceed to step 3
3. Check for faulty Fuse
Board wiring.
Insoect Fuse Board wiring. Ensure all plugs are securely
fastened to Fuse Board. If OK, proceed to step 4.
4. Verify that FC1 and
FC2 Fuses on Fuse Board
are not open.
Remove FC1 and FC2 fuses from fuseholder. Measure
continuity across fuse. If fuses are open, proceed to section
titled ‘‘Open FC1 and/or FC2 Fuses’’. If fuses are OK,
reinstall them and proceed to step 5.
5. Verify that 240vac
Voltage Selector Plug
is not installed with a
120vac fi eld power supply
Check that proper Volatage Selector Plug is installed in Fuse
Board. If OK, proceed to step 6
6. Check for defective
Transformer.
Disconnect plug from P4 connector from Fuse Board. Mesure
for 24VAC between pins 1 & 2 of plug of Transformer and
120VAC between pins 4 & 6. If 24VAC or 120VAC is not
present, replace Transformer. Otherwise, proceed to step 7.
7. Fuse Board is defective Replace Fuse Board.
Low voltage
circuit fault.
1. Check for Low Voltage
Output from Fuse Board
Diconnect plug from P5 connector from Fuse Board. Measure
for 24VAC across pins. Reconnect plug. If OK, proceed to
step 2. Otherwise, proceed to step 5.
2. Check for faulty
Control Module wiring.
Inspect Control Module wiring. Ensure all plugs are securly
fastened to Control Module. If OK, proceed to step 3.
3. Verify low voltage
input to Control Module.
Verify 24VAC across R and C terminals on Control Module.
If not OK, replace harness. If OK, procced to step 4.
4. Verify that F1 Fuse
on Control Board is not
open.
Remove F1 fuse from fuseholder. Measure continuity across
fuse. If OK, replace Control Module. If fuse is open, proceed
to section titled ‘‘Open FC3 or FC1 Fuses’’.
5. Verify that FC3 on Fuse
Board is not open
Remove FC3 fuse from fuseholder. Measure continuity across
fuse. If fuse is open, proceed to section titled ‘‘Open FC3 or
FC1 Fuses’’. If OK, reinstall fuse and proceed to step 6.
6. Check for defective
Transformer.
Disconnect plug from P4 connector from Fuse Board. Mesure
for 24VAC between pins 1 & 2 of plug from transformer.
If 24VAC is not present, replace Transformer. Otherwise,
proceed to step 7.
7. Fuse Board is defective Replace Fuse Board
