2004 Pontiac Grand Prix



February, 8, 2008 AT 10:21 AM

Heater problem
2004 Pontiac Grand Prix 6 cyl Front Wheel Drive Automatic 46000 miles

Blower will not shut off even when key is off and out of the ignition. It is stuck in the high position and it cant be controlled. I have unplugged the connector that is going to the speed control and temp setting switch(I can control the temp) and it still runs on high. If I unplug the connector at the blower motor it will stop. Any suggestions

7 Answers


brian 1

February, 8, 2008 AT 8:58 PM

You have to install a capacitor at the blower motor. Here is a bulletin for this problem. Some customers may comment on an inoperative or intermittent Heating, Ventilation and Air Conditioning (HVAC) blower motor. Others may comment that the blower motor speed may momentarily drop or that the blower motor continues to run after the key is turned off. This condition may be caused by a voltage spike from the wiper motor. The voltage spike may cause a logic lock up in the blower motor control module that may be either momentary or permanent. Disconnect the negative cable from the batteryRemove the right closeout/insulator panel. Disconnect the wire harness connector to the blower motor control module. Install a capacitor, P/N 25073556, into the blower motor control module connector using the following steps. Refer to the illustration above to locate the positive and negative leads of the capacitor. Strip a short length of insulation from the red wire in cavity C, circuit 442, of the blower motor control module connector. Using a splice clip from the J-38125 Terminal Repair Kit, crimp the positive lead of the capacitor to the red wire.

Strip a short length of insulation from the black wire in cavity A of the blower motor control module connector. The circuit number for Buick vehicles is 1450 and for Pontiac vehicles it is 150. Using a splice clip from the J-38125 Terminal Repair Kit, crimp the negative lead of the capacitor to the black wire.

Solder both crimp connections.

Cover both crimp connections with electrical tape.

Tape the capacitor to the blower motor control module wiring harness and cover it completely with electrical tape.

If the customer concern was of a blower motor that continues to run after key off, then replace the blower motor control module and install the capacitor. Reconnect the blower motor control module connector.
Install the right closeout/insulator panel. Reconnect the negative cable to the battery. Here is the part # to the capacitor 25073556



February, 13, 2008 AT 2:03 PM

Hey Brian1,

Where did you find this bulletin? I have a 2000 Pontiac Grand Prix GTP with the automatic climate control that the blower motor would come on after starting the vehicle even though I had the heat/AC off. And sometimes, it would take a few minutes for it to come on even though I had the heat turned on. The last time, it took about 5 minutes for it to come on, after that, it wouldn't come on at all. I also had a bad rain water leak into the passenger's side floor board before this happened, it was due to a flap under the plastic cowl that was sending the water into the blower motor. I tested the blower motor outside of the car and it worked fine. Could it just be that I need to add the resistor in the above bulletin?

I would really appreciate a reply. Those blower motor control modules are $100, I would hate to replace it if I don't have to, thanks.


brian 1

February, 13, 2008 AT 7:49 PM

To answer your question I got the bulletin from the dealer.(I work at the dealer that how I got it)to answer your other question when you had the water leak it probably got on the resistor and could have shorted it out. For you to fix it wright read the bulletin again. You have to install a capacitor also to fix this problem. If you put a resistor in it might only fix half your problem. It's hard to fully answer your problem without actually looking at the car. This is the best advise I can give you.I would post a picture of the capactor but I don't know how. Post back with what you find.



February, 14, 2008 AT 1:39 PM

I will be trying the capacitor first. Radio Shack doesn't have one, so I'm hoping a friend of mine can pick one up at work. I have the automatic climate control, which means it has a mini-computer controling the blower motor instead of the resistors. That's a $100 item as opposed to a $20 one. I wish I had the resistor, I would have replaced it already. Thanks for the replies and sorry for taking over this topic.



February, 18, 2008 AT 11:37 AM

OK, this is what I found.

1) No power to blower motor - already knew that

2) No signal coming from Heater/AC Control in dash to the blower motor control module

3) C1 - C12 has 12V on the Heater/AC Control connector in dash

4) With ignition in run position, C1 - C5 has 10.5V on Heater/AC Control connector

5) No shorts or opens on any related circuits

Now ALLDATA says, based on these measurements, the heater/AC control needs to be replaced. However, I am concerned about this 10.5V. I wonder if it is related to my other problem.

I also have this problem with there only being around 10V at the batter after starting the car and shutting it off a couple times. I usually have a hard time starting it and have to jump start it every couple times. I got a new battery and it does the same thing, the old one actually tested as good. I noticed that if I took a long ride, (> 30 minutes), it will start without a problem. It's those short trips to the store that really causes it to need a jump start the next morning. It also seems to not matter if the car sits for a few hours or a few days. I took a 2 hour trip and parked it for 3-4 days and it started up without a problem. But my girlfriend has driven it a couple blocks down the street to get gas and it wouldn't start at the gas station.

I really want to figure this out without spending money on unnecessary parts. Thanks for any replies.



February, 20, 2008 AT 12:36 PM

OK, I replaced the ignition starter switch and it brought the run power up to 12V like it should be. But the heater/AC control still doesn't work. Waiting to get one in by Friday. Will post back with the results. Why do I have all these problems with this car? I have a 1990 Jeep with all original stuff like this and it still works flawlessly. I guess you have to buy new and get rid of it within 4 years.



March, 9, 2008 AT 9:20 PM

It turned out to be the blower motor control module. I thought it was still not working, until it finally came on 20 minutes later.

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