Question about my cars AC system? My blower won't go off, even when my car is turned off and keys are out.?

just happened today. My AC works fine. Blows cold air but today another fan came on that blows only at my feet. Well it won't turn off. I have to disconnect the batt. to stop it. I've looked on the internet and most people say bad Blower Resister but that seems to be an issue for the AC that blower going through its different speeds.. My AC works fine but this other blower, I don't even know what it is, keeps blowing hot air at my feet. I have a 2004 GMC envoy SLT v8 engine if that helps. It has dual auto climate control.

1 Answer

  • paul h
    Lv 7
    5 years ago
    Favourite answer

    Possibly a problem with the control head/programmer module or bad servos for lower vent air flow mode door and temp blend door...or mode/temp doors stuck in position, etc... The blower staying on could also be a stuck relay or bad control head/module. The blower resistor pack is used in conjunction with the fan speed switch to set fan speeds...if it goes bad and melts wiring, it could cause a cross-arc of power which may keep the fan blower on although the control head should turn off power to the fan motor after a while.Try puling the fuse for the HVAC system...wait 10 minutes or so and reinstall...that may reset the system.

    Removing and re-installing the fuse for the HVAC Control Module (found in the Rear Fuse Block located under the driver's side rear seat) will reset the control head and possibly allow it to resume normal operation.

    The control head on auto climate /dual zone systems stays powered up for 4+ hours so if it's defective, it might keep power to the blower motor (there is only one) and also may cause the servo for the lower vent or temp doors to stay in wrong positions. My guess is the control head is bad but pulling the fuse may reset it. Check with GM for any related TSB's on the issue..

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