Can anyone provide resistances for the blower motor power stage so I can trouble shoot it? My fan stopped,no blinking lights on ECC unit,and I think it could the power stage(actually the resistors for the blower motor speeds). Also, where is the relay for the blower motor located? My Haynes manual doesn't help much in this area. AC cycles on with AC on/off and cycles on with defrost setting. Just no fan at any speed setting.
If your unit has continuously-variable blower speed, the "power stage" and is a heat sink for one or more transistors that supply the current to the fan motor. The factory manual lsits either DTC codes (connector B1) or substitution for troubleshooting this part.
The schematic also shows a manual system, where there there are several fixed blower speeds. This uses a resistor pack Pin 4 (green wire) is the common, and three resistors go from there to pins 1,2,3 (black, black/white, brown)
They don't show the resistor values, but if one was bad, it should still work on some speeds.
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The problem with no fan on any speed was the resistor for the blower motor. I bought a used one and changed it out. None of the codes I pulled on my 94 850 said "bad resisor". There was tons of crap about shorted to ground sensors- about 15 different codes. I think the system just is not set up to diagnose a bad resistor for the blower motor. Thanks- JDG
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