Advice on A/C Problem and Service Bulletin

mtcrumb · Aug 1, 2012

Having a problem with the musty odor on start up of 2008 Tahoe. Had it at the dealer yesterday for service and was told nothing could be done. I started looking around and found this on another site. Have any of you had this done and did it fix the problem? Thanks

TIP: Do not enable the afterblow function until its purpose and operation are explained to the customer and they approve the change.

Once the afterblow option has been enabled, the blower motor will turn on approximately 10 minutes after the vehicle is shut off. The blower motor will run continuously for 10 minutes at a 30% duty cycle. The afterblow function will activate only if the air conditioning compressor was engaged during conditions of high ambient temperature. If the vehicle is started within 10 minutes of the last key off, the afterblow function from the previous key cycle will be cancelled.

Turn this option ON in the HVAC Control Module instead of installing the Electronic Evaporator Dryer Module Kit referred to in the Air Conditioning Odor bulletin 99-01-39-004A.

To enable afterblow:

1. Verify the Tech 2 is updated with the latest software.

2. “Build” the vehicle on the Tech 2.

3. Use the following Tech 2 pathing:

Vehicle Control Systems > Select engine > Module Setup > HVAC Control Module > Afterblow Option

4. Follow the on-screen directions.

LTLux · Aug 1, 2012

I have not seen or heard of that but it might work. If it's not under warranty then it will run you about $100 to get it flashed at the dealer.

I have that smell but it comes and goes. You can take the blower motor out from under the dash and use some lysol and spray a good bit up there and it will kill some of the mold and make it smell better. I also turn my air off about 5 min before I get where I'm going to give the system time to dry out.

mtcrumb · Aug 1, 2012

Thanks

This is the wife's car....getting her to turn off the A/C before pulling into the garage... :Nonono:

well you know how that goes. It is under warrenty. Just looking to see if anyone used this?

Modded · Aug 1, 2012

I had the afterblow function enabled on my A/C almost three years ago. It turns on after I turn off the car on hot days. My musty odor has not come back since.

mtcrumb · Aug 1, 2012

Thanks

Thats what I was looking for. I think with most of her short trips and parking in the garage added with our high humidity this sounded like it should fix the problem.

mtcrumb · Aug 3, 2012

Update on A/C

Just wanted to provide an update to anyone with the same problem. Took the Tahoe back to the dealer yesterday with the printed Bulletin in hand. This visit they were very helpful. To prevent this re-occurrence of musty smell the evaporator core was cleaned with something to eliminate microbial grow that smells very clean(sorry don't know the name) The after blow option was activated, all actuators were recalibrated , Then topped off with freon. All was taken care of under warranty. No more musty smell. Very cool fix.

GM Customer Service · Aug 3, 2012

mtcrumb said:
Having a problem with the musty odor on start up of 2008 Tahoe. Had it at the dealer yesterday for service and was told nothing could be done. I started looking around and found this on another site. Have any of you had this done and did it fix the problem? Thanks

TIP: Do not enable the afterblow function until its purpose and operation are explained to the customer and they approve the change.

Once the afterblow option has been enabled, the blower motor will turn on approximately 10 minutes after the vehicle is shut off. The blower motor will run continuously for 10 minutes at a 30% duty cycle. The afterblow function will activate only if the air conditioning compressor was engaged during conditions of high ambient temperature. If the vehicle is started within 10 minutes of the last key off, the afterblow function from the previous key cycle will be cancelled.

Turn this option ON in the HVAC Control Module instead of installing the Electronic Evaporator Dryer Module Kit referred to in the Air Conditioning Odor bulletin 99-01-39-004A.

To enable afterblow:

1. Verify the Tech 2 is updated with the latest software.

2. “Build” the vehicle on the Tech 2.

3. Use the following Tech 2 pathing:

Vehicle Control Systems > Select engine > Module Setup > HVAC Control Module > Afterblow Option

4. Follow the on-screen directions.

I would like to apologize with the concern you are having with your vehicle. I would like to look into this concern further for you. Can you please send me your full name, address, phone number, vehicle mileage, VIN and the name and city of your dealership so I may proceed?

Louis
GM Customer Service

mtcrumb · Aug 3, 2012

Last Post

Please see above the problem was taken care of at the dealer yesterday.
Thanks for your offer to help.

Chrisalecia · Jul 29, 2013

do you have to leave AC on for afterblow to engage?

I had the Afterblow function enabled in my AC Control Module at the dealer. They knew exactly what it was when I asked for it then they said they checked the functionality after they made the change.

I've tried twice to get it to work but it doesn't come on. Here's what I know:

1. AC must have been on for at least 10 minutes
2. if you turn on the vehicle before the 10 minutes the system will reset itself
3. It must be 70d or higher outside temp

I've had all of that and nothing. I turn off the AC before I turn off the truck. Do you have to leave the AC on? I'll try that and if it doesn't work it looks like I'm back to the dealer - which I hate.

guy from norcal · Jul 29, 2013

yeah the wifes yukon gets that smell sometimes too. she doesn't turn the a/c off before the driveway either :emotions34:

auto zone sells this spray that goes behind the glove box that kills any mildew and smells good

Advice on A/C Problem and Service Bulletin

mtcrumb

TYF Newbie

LTLux

Full Access Member

mtcrumb

TYF Newbie

Modded

That Guy

mtcrumb

TYF Newbie

mtcrumb

TYF Newbie

GM Customer Service

Full Access Member

mtcrumb

TYF Newbie

Chrisalecia

Member

guy from norcal

Full Access Member

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