Thread: Intermittent HVAC blower

Hey boys and girls, I've been an avid reader for the last couple months; looking at a few mods I'm thinking about undertaking. For the past 6 weeks I've had one problem after another with the car and the forum has helped me solve all those problems up until today.

My HVAC blower fan started cutting in and out today. I have the 2004 GP, no digital controls (3 knobs only). The fan works on every setting, switches positions, blows cold air, blows hot air (thanks to the heater core flush accomplished with help from this site 2 weeks ago) but when I hit bumps on the road, the fan dies out. Sometimes it just cuts out and comes right back on, sometimes it will cut out until I hit the next bump. Like I said, works on all speeds so I'm thinking its not the resistor, there are no other accessory issues, so I don't think its the ignition switch. I'm thinking its some sort of electrical issue. I'm not an electrical guy so I'm wondering if anyone has run into something similar or might have any suggestions where I should start looking. Any known issues with connectors, grounds, etc?

check the wires going to the motor, or it could be the motor its self.

Ahhh, its cutting in and out even when on full speed, which leads me to think its NOT the resistor. I guess I'll dig in there tomorrow and have a look, I was just trying to avoid it having already done it on a couple other GMs. At 6'2" and 240lbs I do not fit easily under the dash, haha.

I planned on pulling the blower motor resistor and replacing it, seeing as (I thought) it was only around $30. Got to the parts store, they list the resistor for the '04-'08 model at $120???? At that price point I'm gonna have to do some more accurate troubleshooting. I spent the afternoon driving around trying to get the fan to cut out, then pulling over to check connections. I had it basically narrowed down to the actual plug into the blower motor. CK115, you just picked up a new connector (2 wires from the resistor, to the blower)? I think I'll try to pick one up tomorrow, but I'm going to have to track down some grounds and look into that as well. 3 or 4 times I got a "Charging System Failure" message flash on and off with the fan as well. I'm done for now, its -35 outside and the 4 car shop I normally use has 6 cars jammed in it - typical. We had a -30 degree cold snap a couple weeks ago when my heater core decided to stop blowing hot air too.

Alright, I did some more digging and it looks like someone else on here was having some brutal mileage due to a bad battery draining the charging system. I'm also having some pretty crappy mileage. I had chalked it up to the winter tires, remote starter, and more idling in the cold weather but maybe I've got a battery or alternator issue. Lots of exploring to do in the morning; I'll keep everyone posted.

As for my earlier post, for anyone who has replaced the blower motor resistor on the 2004, does $130 sound reasonable? The picture of the part (wasn't in stock) didn't look like any GM blower motor resistor I've ever seen before, and like I said, is about $100 more than the others as well.

well i see one wrong thing in that picture...made in mexico =P

I changed out the blower motor and so far the problem's solved. Looks like it was the blower itself. About 6 hours of diagnostics but less than 45 minutes to swap it out, including the trip to the parts store. Glad it wasn't the resistor, that one looks a little more awkward to get at.

Originally Posted by cleangtp

Good deal man but it takes literally 3 minutes to take out the blower and hook it up to 12v lead. Resistor is easy take out the 2 bolts you can see, wiggle the resistor and it comes out or breaks. Then you just reinstall the new with 2 bolts done. Shouldn't have took 6 hrs but I'm glad you have heat now!

It took that long to reliably replicate the problem so I could track it down in the first place. Opening and closing the door would shake it enough that it would start working again, undoing my seat belt, put the car in park too hard, every time I'd go near the connections it would start working again. She was being a really bastard, haha. In any case, all good now.