Checking Cables, Blower Fan Does Not Start
Check MCC control module, fan resistor and blower fan connector for contact resistance and oxidation according to Contact Resistance And Oxidation . Check that connectors are connected correctly.
Check that the blower fan is not blocked or turning slowly.
Check power supply between MCC control module #A1, #A2, #A3, #A5 and fan resistor terminals 2, 6, 4, 1 for an open-circuit according to Open-Circuit, Permanent Faults and a short-circuit to ground according to Short-Circuit To Ground, Permanent Faults .
Check the power supply between MCC control module #A6 and blower fan for an open-circuit according to Open-Circuit, Permanent Faults and for a short-circuit to ground according to Short-Circuit To Ground, Permanent Faults .
Check power supply to MCC control module #A4 for an open-circuit according to Open-Circuit, Permanent Faults .
Check ground lead between blower fan and ground terminal for an open-circuit according to Open-Circuit, Permanent Faults .
If the cables are OK, try a new blower fan resistor or a new blower fan.
Remedy as necessary.
Other information:
- To access/replace the control module, refer to Replacing ECC Control Module .
- To access/replace the blower fan resistor, refer to Replacing Blower Fan Rheostat (MCC) .
- To access/replace the blower fan, refer to Replacing Blower Fan Motor .
- To connect the breakout box, see Connection Of Breakout Box MCC .
- For information on signals, refer to Signal Descriptions MCC .
- Continue
Refer to Verification