This 2004 Pontiac Grand Prix came in with a complaint that the blower had stopped working and the customer saw smoke from under the passenger side of the dash. Inspection at the under hood fuse box found a blown 30 amp fuse.
I replaced the fuse.
The new fuse is the square pink fuse second from the left.
I checked and found the blower would work but made a terrible noise and would not turn off.
Time to change the blower motor and blower motor speed controller. I started by removing the passenger side lower hush panel by removing several push pin retainers.
I removed the courtesy light from the panel.
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Then I could access the motor assembly for removal. Three screws and a harness connector and it was out of there. The blower motor speed controller was put on at the factory by melting retaining bosses to hold the assembly together.
I had to use a screwdriver and pry the unit from the housing and installed the new one with screws to hold it in place.
I also checked and replaced the dirty cabin air filter which is probably what helped cause this problem. Click here to see that post.
Ok I checked the voltage to that ground and it is 0. Faulty resistor was my first diagnosis so I replaced it with three different brands to check it as I stated in first post, but none of them did anything(fan didn’t turn). Three different parts stores. The old one barely spun the fan but it spun. All the ones I checked did nothing. Then I accidentally broke the old one and bought one that’s supposed to cross-reference with my car from AutoZone and this one matches all the ones on EBay for my type of car. How can all of them not work? The old one spun the fan enough to give my ac a breath out of vents?
My guess would be that you have not yet confirmed the condition of the ground on the large black wire that is not going to the blower motor. Key on and blower set to high. What is the voltage on that wire when checked to a known good chassis ground point? If it is anything other than a nominal 0-1 volt there is a problem with that ground. If it is withing that range the new blower speed controller (resistor) is faulty. This system uses the ground side of the battery to control blower operation. Battery power is a constant.
Ok. I broke the module so I replaced it. Also got a climate control unit. Fan still not turning (its new and I connected it to battery to test) the wires running to the modules are as follows, black, tan i@ black, red, purple, black(the purple and black run into fan also) with all harnesses connected, the voltage I get from signal wire (tan/black. Mines not purple/white)
Is 7.1 on the fan speed notch low. With the fan speed selector on high I get just over 2.0 volts? The purple wire running into fan is 12 volts. I think I fried my brain. What’s could it be? Checked the grounds wires from the harness at passenger door under carpet and behind radio. Is there any others? I’m lost. Please help.
I also took pictures to email you if you want.
Thanks
You have lost me on the tan wire. I am thinking it should be purple. GM does not show a tan wire for the blower speed controller in the diagrams. Two black wires, one red, one purple and one small gray wire with a black stripe.
You are thinking about this incorrectly. The control panel sends a pulse width modulated ground signal out on the small gray/black wire to bring down the voltage that is outputted from the blower speed controller. Nothing will happen if you test with the wiring disconnected. Most GM blower speed controllers have between 5 and 10 volts on that circuit. Yours seems high at 13.4. That is why I mentioned testing the ground integrity. A weak ground could let that voltage go higher.
The wires come from climate control unit to resistor/module and then 2 wires to the blower motor. One black one tan. The tan runs a constant 13.4 volts no matter what the fan speed selector is at. The signal wire from climate control unit still 0_.10 of a volt depending where speed selector is at (highest speed .10 of a volt). The red wire going into module does have power @12v. I checked the ignition switch for low voltage and that is ok also. All wire condition is fine. Is the signal wire voltage supposed to be that low of a range?