I have a 2004 Pontiac grand prix, when I turn off my car my heater fan motor stays on… could anyone please tell me what could be the cause of this?
Probably a virus or malware in your cars computer, this happens when you go through car washes, they implant viruses in your car. Really I toy with you because you have supplied zero information that would aid us in helping you, like how long has this been happening, is it just on high speed? please some details.
Do you mean your heater fan in the dashboard or the fan near the radiator in the engine compartment? What happens if you remove the key?
Try to notice if any other things, like the radio etc. that should turn off also stay on.
The problem might be in the blower motor control processor. This is what grounds the blower motor circuit so the blower runs. The speeds of the blower motor is controlled thru the HVAC module. If the processor has failed where it no longer ungrounds the circuit, the blower motor will continue to run even with ignition off.
Tester
It stays on high speed, all the other controlls for the heat/air work fine, this just started yesterday, I have pulled all the fusses individually, it doesn’t cut off, even the relay fuse, the only way of turning it off is unhooking the battery!
How could I fix this?
Where Is the controll proceessor located and where is the HVAC module located?
Locate battery main fuse 30, 30 amp. This supplies constant voltage to the blower motor control processor. Pull the fuse and if the blower stops functioning, the processor isn’t ungrounding the circuit.
Have you had the cabin air filter replaced lately? If so, the water deflector may have been left off. This then allows water into the blower plenum rusting the blower motor and the processor which is part of the blower motor. Refer to TSB 03-08-57-006B for this problem.
Tester
Also,This is my girlfriends car and I asked her about the cabin air filter being replaced and she said not to her knowledge. But we have noticed some water coming in on the floorboard but we can’t tell where it’s coming from. It seems to be coming in from the front but we can’t pin point exactly where the water is entering the car.
Try pullin fuse#30 green 30 amp & #18 red 10 amp under the hood,if its still runs pull the HVAC fuse located in the fuse panel in the car it should be a red 10 amp.
Thank you very much for the information that you supplied on the issue of the Heater Fan Motor. It was very helpful, We will now be able to correct the problem W/ the Heater Fan motor.
Thanks Again,
Ronnie
The controller for the blower motor speed is usually mounted near the motor and to the side of the air ducting to allow for cooling of the module. Hopefully you can follow the wires from the motor which then tie to the module. The module is wired in series with the power to the blower and most likely has a shorted transistor inside it (not a short to ground) which allows power to run directly to the motor keeping it turned on. The module is used to control the speed of the motor through the HVAC control module. The modules run around 130 dollars or so.