2008 Yukon Denali - weird issue

[ktsanf]

Hi all, first post. Have a very weird issue going on with my 2008 Yukon Denali. Front blower started acting weird, so I replaced the blower motor resistor. The weird part was it didn’t work at all after replacing, and then started working about two hours later, and has been fine for a while. Then it did something different where the fan would run without the car running. So I replaced the blower motor resistor again, and it’s been fine for quite a while. But now I have no front blower fan at all (The fan display works where it shows the fan going from low to high). The front fan does not run, but the rear blower does. Took the blower motor out of the front and put power to it and it spins fine. Fuses are fine. I’m thinking the HVAC control module? I searched through out the forum and couldn’t find anything similar to this problem.

Appreciate it greatly if anybody has any ideas what to do on this craziness....

 

[CaptainAmerica1]

Check the resister again. If it was the control module I assume the rear would exhibit the same symptoms as the front. You’ve checked everything else and the resister is easy enough to check with a dvom so I’d start there.

 

[gooffeyguy]

The fan running after vehicle is shut off sounds like the afterblow function was enabled, which can only be done by a dealer or someone with a two-way diagnistic tool such as a Tech2.

There was a TSB about it. Have you ever taken it in due to a musty smell from the air vents?

Sent from my SM-G930V using Tapatalk

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics, please.


Other folks will chime in with their suggestions.

 

[ktsanf]

Check the resister again. If it was the control module I assume the rear would exhibit the same symptoms as the front. You’ve checked everything else and the resister is easy enough to check with a dvom so I’d start there.

Thanks for the reply. I was going to try that as well. I think I may try a new blower motor because when I had the existing one out it was sort of hard to turn. I read elsewhere online that if the blower motor is failing it might be using more power than usual and causing issues with the resistor. I know it wasn’t spinning freely by hand and I thought it was odd that it needed a little bit of force. Luckily, my brother owns an auto parts store.

 

[ktsanf]

The fan running after vehicle is shut off sounds like the afterblow function was enabled, which can only be done by a dealer or someone with a two-way diagnistic tool such as a Tech2.

There was a TSB about it. Have you ever taken it in due to a musty smell from the air vents?

Sent from my SM-G930V using Tapatalk

Thanks for the info. There’s been no musty smell at all and no one has touched the vehicle since we’ve owned it.

 

[petethepug]

Sounds like a bearing on its way out on the fan. If there’s any resistance on the motor you pretty much nailed one of the problems in the issue.

In my other car the resistor pack is the first thing to go when the supply fan is going out. Strangely the fuse never goes, the resistor pack goes first. Clean off your evap coils when you’re in there, if possible. It’s also a good time to add the cabin air filter when all is apart.


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[91RS]

It isn't a resistor if it has auto HVAC it is a blower motor control module. Did you buy a GM one or aftermarket? I would buy a GM one if you bought an aftermarket one.

 

[ktsanf]

Sounds like a bearing on its way out on the fan. If there’s any resistance on the motor you pretty much nailed one of the problems in the issue.

In my other car the resistor pack is the first thing to go when the supply fan is going out. Strangely the fuse never goes, the resistor pack goes first. Clean off your evap coils when you’re in there, if possible. It’s also a good time to add the cabin air filter when all is apart.


Sent from my iPhone using Tapatalk Pro

Thanks for the reply. Yeah, it needs force to spin it. I just replaced it and so far all good......

 

[ktsanf]

It isn't a resistor if it has auto HVAC it is a blower motor control module. Did you buy a GM one or aftermarket? I would buy a GM one if you bought an aftermarket one.

Correct, control module. I tried one after-market and one GM. Just replaced the blower motor, all good (so far......).

Thanks to everyone who has offered suggestions on this issue. Greatly appreciated.