2004 Grand Prix blower motor???? GM Tech. help?

[mcbassin]

On the way home last night in our 2004 Grand Prix the blower motor for the a/c heater just quit. I have researched it a little on google but I'm still a little confused.
I have read where the control module or resistor will keep them from running but I removed it and have hooked up direct 12 volts from another car battery and it blows full blast.
I checked the connector with a DVM and it goes from about 10v when all the way down up to about 12.5 all the way up. It looks like there is voltage to the fan so I hate to spend $60 plus for the resistor or $50 plus for the fan only to find out its something else.
Any GM techs. mind helping me diagnose further before buying parts? thanks

[72chevyk10]

may be a dumb question and i dont really know about it, but have you checked the fuses?

[mcbassin]

Well, since I'm getting 12 volts at the plug
I really didn't see any need to check it
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[Restrorob]

If your getting voltage to the fan motor make sure it's getting a good ground....

[mcbassin]

Originally Posted by Restrorob

If your getting voltage to the fan motor make sure it's getting a good ground....

I'm not sure how to check that since the housing is plastic and I think it pulls the ground from the connector? If there is a seperate ground I couldn't find it. I looked thinking the same thing.

[hayhauler71]

. Check voltage on the Gray/Black wire at the blower control module, check for 8 volts on high blower speed and about 2 volts on low speed . If it is OK, check the B+ on the Red wire and ground. Before replacing the blower module, amp draw the blower motor. The blower motor should draw less than 15 amps running on the Black wire. If all this is good, then the blower module needs to be replaced

[mcbassin]

Originally Posted by hayhauler71

. Check voltage on the Gray/Black wire at the blower control module, check for 8 volts on high blower speed and about 2 volts on low speed .

I checked the voltage on the gray/black wire here are the results:
with the knob all the way down 5.38 volts as I turned it up the voltage dropped to 1.34.
Does the fan need to be connected? It wasn't

Originally Posted by hayhauler71

If it is OK, check the B+ on the Red wire and ground. Before replacing the blower module, amp draw the blower motor. The blower motor should draw less than 15 amps running on the Black wire. If all this is good, then the blower module needs to be replaced

Not sure what the B+ is? I checked the voltage from the Red wire to ground and it was 11.95 and when I switched the knob it stayed the same.
I don't have an amp probe or amp meter to get the load amperage?

[mcbassin]

What baffles me, If there is 12+/- volts going to the fan, why wouldn't it run? Do they work different from a standard 12 volt lamp or similar device?

[68C15]

current flow;
battery, fuse, fan motor, resistor(or module if you have auto temp control), switch, ground.

if the fan is totally inop I usually find either a bad motor (tap with hammer handle to diagnose while on high) or melted connections at resistor.

if fan quit on only one or 2 speeds I usually find a bad resistor

[mcbassin]

Originally Posted by 68C15

current flow;
battery, fuse, fan motor, resistor(or module if you have auto temp control), switch, ground.

if the fan is totally inop I usually find either a bad motor (tap with hammer handle to diagnose while on high) or melted connections at resistor.

if fan quit on only one or 2 speeds I usually find a bad resistor

So, just plug the fan in turn it on high and hit with a small hammer on the side? It will work intermittendly? If so, replace the fan? It will work when I connect it directly to a battery.

[fine69]

If you pull your resistor out you will be able to tell if it is bad.

I have replaced plenty of them. And there is always a burnt spot on the resistor.

[mcbassin]

Originally Posted by fine69

If you pull your resistor out you will be able to tell if it is bad.

I have replaced plenty of them. And there is always a burnt spot on the resistor.

I think that thing is riveted in? Just drill those out to remove it?
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[463]

in the last year or so what i have seen is on the early 2000 car/truck is the the resistor burns and when it is replaced it will normal run the year and burn out a gain. this seems due to the blower on the way out. the blower will run but is pulling slightly higher amps than the factory specks. so to fix the proper way is a resistor and blower motor at the same time. i think they have to step up and builid a better resitor. in the older cars what has been said it what i have found to work.

[GruntMoanCough]

I replaced the resistor on my '02 Grand Prix and within 6 months (of kicking the heater box ), the motor stopped all together. It's all good now.

IIRC, the resistor was held in with 3 hex head screws (7mm?)

[mcbassin]

Originally Posted by 463

in the last year or so what i have seen is on the early 2000 car/truck is the the resistor burns and when it is replaced it will normal run the year and burn out a gain. this seems due to the blower on the way out. the blower will run but is pulling slightly higher amps than the factory specks. so to fix the proper way is a resistor and blower motor at the same time. i think they have to step up and builid a better resitor. in the older cars what has been said it what i have found to work.

Well,
after reading this, I just ordered a new fan and resistor.

Originally Posted by GruntMoanCough

I replaced the resistor on my '02 Grand Prix and within 6 months (of kicking the heater box ), the motor stopped all together. It's all good now.

IIRC, the resistor was held in with 3 hex head screws (7mm?)

Man, I would swear this thing is held in with rivets? I will check it out when I get the parts. I quit driving this car this week since the temp is in the 20s to 30s.

[68C15]

Originally Posted by GruntMoanCough

IIRC, the resistor was held in with 3 hex head screws (7mm?)

there is 3, they take a 5.5mm
you will need a swivel socket to get to the one by firewall. here's a tip, that one at front is a bit**. use a utility knife and cut away some of the firewall sound insulation

[mcbassin]

Originally Posted by 68C15

there is 3, they take a 5.5mm
you will need a swivel socket to get to the one by firewall. here's a tip, that one at front is a bit**. use a utility knife and cut away some of the firewall sound insulation

Tell me I ordered the right part? I thought this is the resistor. It doesn't have screws. I guess these have to be drilled out?

[68C15]

that looks like a blower control module. it serves the same purpose as a resistor. the HVAC computer sends a pulse width modulated signal to turn on and off a solid state switch which in turn controls blower speed.

red is ign. power, black is ground, gray is control signal, purple is blower power while the black next to it is blower ground.

borrowed from hayhauler post; Check voltage on the Gray/Black wire at the blower control module, check for 8 volts on high blower speed and about 2 volts on low speed . If it is OK, check the B+ on the Red wire and ground. Before replacing the blower module, amp draw the blower motor. The blower motor should draw less than 15 amps running on the Black wire. If all this is good, then the blower module needs to be replaced

when replacing module you remove the heads of rivets and install new unit with screws in the other holes visible in picture. they do it that way as it's quicker on the assembly line than using screws.

I should add that this design of blower control has a shorter life span that a resistor and is a common failure item. the large transistor inside gets overheated and the molecular structure of the emitter blows in the same manner as a fuse. a new blower motor would be a good idea to prevent premature failure of new module.

[mcbassin]

Originally Posted by 68C15

that looks like a blower control module. it serves the same purpose as a resistor. the HVAC computer sends a pulse width modulated signal to turn on and off a solid state switch which in turn controls blower speed.

red is ign. power, black is ground, gray is control signal, purple is blower power while the black next to it is blower ground.

borrowed from hayhauler post; Check voltage on the Gray/Black wire at the blower control module, check for 8 volts on high blower speed and about 2 volts on low speed . If it is OK, check the B+ on the Red wire and ground. Before replacing the blower module, amp draw the blower motor. The blower motor should draw less than 15 amps running on the Black wire. If all this is good, then the blower module needs to be replaced

when replacing module you remove the heads of rivets and install new unit with screws in the other holes visible in picture. they do it that way as it's quicker on the assembly line than using screws.

I should add that this design of blower control has a shorter life span that a resistor and is a common failure item. the large transistor inside gets overheated and the molecular structure of the emitter blows in the same manner as a fuse. a new blower motor would be a good idea to prevent premature failure of new module.

I really don't know what you guys are talking about "B+" on the red wire?
I did the rest of the volt meter test results above.

I have already ordered a new blower and module/resistor so when I get those parts in I'm just going to replace both. I was hoping to avoid the high price of replacing both but after reading what you fellows wrote it's just insurance that we won't have to mess with it for another 7 years.......... hopefully

[mcbassin]

Here's another weird thing. I had a quick errand to run last night so I thought I'll just take the GP. Well, we got a few miles down the road and decided it was a bad idea without the blower motor installed. It just blew icy air into the cabin. I stopped at a gas station and stuck the fan back in to fill the hole. I thought well I might well stick the plug in for kicks. It fired right up? It was pretty loud right down there by it, so the fan is more than likely toast but it has been working flawless since I put it back in last night.

When I get the new fan, you guys think I should still replace the fan and controller??