94 850 with ECC- no fan

Discussion in 'Volvo 850' started by JDG, Jan 14, 2006.

  1. JDG

    JDG Guest

    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.
     
    JDG, Jan 14, 2006
    #1
  2. JDG

    Doug Warner Guest



    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.
     
    Doug Warner, Jan 15, 2006
    #2
  3. JDG

    JDG Guest

    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
     
    JDG, Jan 20, 2006
    #3
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