Blower Motor... Revisited

Mattillac · #1 (**permalink**) 12-15-08, 08:10 PM

OK.

I fondly remember this issue when I had my '88 Brougham. The A/C Power Module (which I discovered was the culprit later) had blown on me which caused the blower motor to constantly stay on... and that eventually caused the blower motor to fail. I went back and forth replacing parts until I finally discovered what was happening. Quite fun.

Needless to say I was thrilled when I got into my car on Sunday and discovered the fan to be defunct. Here we go again, I thought. Now some foresight to this story... I was performing the Big 3 upgrade last week (for those who do not know, it's an upgrade to the stock grounds and alternator wires). I accidentally touched the Alt+ wire to a ground source for a split second, which let of a small shower of sparks, but the car seemed none worse for the wear. I know, I should've been more careful. Everything worked fine when I started the car so I thought nothing of it.

So I'm thinking this might've had something to do with it. I dug out all of the old service paperwork (I have it all for the history of the car) and found that the blower motor had actually been replaced only three years ago (14,000 miles ago).

Now my question is - Is this system like the old style with the A/C Power Module and the blower motor, I mean, is there anything else I should check before just replacing the motor? I don't see how it could've gone out so fast even with my little mishap.

(P.S. - I checked the HVAC fuse and all is well)

Thanks!

**Ranger** · #2 (**permalink**) 12-15-08, 08:59 PM

I THINK the '88 may have a separate control module (or whatever it is called) down line from the blower. If so, it will be mounted on top of the HVAC housing on the firewall. It would control the blower speeds. Follow the blower motor wires to it.

Mattillac · #3 (**permalink**) 12-15-08, 09:50 PM

Thanks for the quick reply Ranger but I'm having this problem in my '95 Deville (4.9L non-N*) and I was just providing a little anecdote about my old '88 at the beginning

Sorry for the confusion

**Ranger** · #4 (**permalink**) 12-15-08, 09:56 PM

Oooh, in that case maybe you did fry the motor. I know they are pretty sensitive to their proximity to spark plug wires.

Mattillac · #5 (**permalink**) 12-15-08, 10:15 PM

Do you think that small mishap I had with grounding out the battery might've done it? I don't see any other reason for a 14,000mi old blower to fail

**Ranger** · #6 (**permalink**) 12-15-08, 10:30 PM

It's possible, but I couldn't say for sure.

Tonkin · #7 (**permalink**) 12-16-08, 12:28 AM

I would agree till I lost a 96 blower. Could not understand how a simple motor could go bad. Motors run for years and years and are a simple device. Ahhh, but when I took the motor apart I found why GM motors go bad. The blower motor is fine but the electronics mounted on the blower rotor wheel are the weak link. There is a round circuit board about 4 inches around mounted to the rotor which has 5 Transistors, 3 SCRs, and an IC mounted to it. The SCRs are mounted to a heat sink and the insulator between the insulator and SCR wears through and shorts out the SCR and smokes it. It is a 90 cent part but is a bitch to get to in order to replace. I repaired it just to see if that was what the problem was. Works fine but probable not worth the effort to fix. Took me 3 evenings to fix. So as to your original question could a grounded lead cause the blower to fail my guess would be yes. The blower motor itself is fine but the electronics inside it probable got fried. Now I see why Ranger says the "motor" is sensitive to their proximity to spark plug wires. Never could understand how that could hurt a motor. Now I do, because it takes out the electronics.
12-15-08 05:50 PM

Mattillac · #8 (**permalink**) 12-16-08, 12:37 AM

Crap well I guess I'll start shopping for replacement motors

Thanks guys

Mattillac · #9 (**permalink**) 01-09-09, 04:52 AM

I just wanted to update you guys on the situation... and possibly bash myself for being stupid...

When I installed the larger gauge wire for my audio system, I neglected to re-attach the ground for the blower... I was looking under the hood today and when I touched the wire to a ground point the blower would turn on...

So take me as an example and always check the little things first... I now have a $209 blower motor that I need to return to the parts store.

Thanks again for all of the help.

chubbyranger · #10 (**permalink**) 01-09-09, 07:42 AM

Quote:

Originally Posted by Mattillac

I just wanted to update you guys on the situation... and possibly bash myself for being stupid...

When I installed the larger gauge wire for my audio system, I neglected to re-attach the ground for the blower... I was looking under the hood today and when I touched the wire to a ground point the blower would turn on...

So take me as an example and always check the little things first... I now have a $209 blower motor that I need to return to the parts store.

Thanks again for all of the help.

You're not the first and definitely not the last to get bit by the simple stuff. Check with your parts store though - some do not accept returns on electrical items.