Smell from AC

SAKO79 · June 8, 2016

i have a 2014 gmc sierra 1500 42000km on it. i just started getting a musky/fruity smell from the ac when it first turns on. im still covered under the factory warranty. is this something that the dealer can fix under warranty or is it better that i repair the problem. i changed the cabin air filter at 36000km

bigsam94 · June 9, 2016

ask your dealer to look at it; if they come back and find nothing then ask them to turn on the afterblow feature. It is in the manual.

fondupot · June 9, 2016

ask your dealer to look at it; if they come back and find nothing then ask them to turn on the afterblow feature. It is in the manual.

Hmm. I didn't have any luck finding anything on afterblow in my truck. I too have been noticing a smelly AC system.

Been also meaning to replace the cabin air filter.

bigsam94 · June 9, 2016

Replace the filter, that's 90% of the problem most of the time. I was told it was in the Manual but I haven't personally checked, I will when I get off of work

P.s. Make sure the dealer doesnt drop a bunch of leaves in your AC blower like mine did

DAY11 · June 9, 2016

From other vehicles it seems to be related to running the AC right up until you shut off the veh and moisture collects in the air lines. It molds up. You can help avoid it by turning off ac but leaving the fan on for last (short) portion of the trip to allow the air to blow and cut down on moisture. (water collects in the lines as it is drawn to cold like it does to the outside of an iced tea glass.) Turning off the AC in effect allows the lines to warm up a little closer to ambient air temp and the air movement reduces the moisture already there.

To reduce the smell there are products you spray into the intake at windshield that gets drawn into the system to "clean" the lines. I've heard of just misting Simple Green in and it made a huge difference without buying a special product. Turn off recirculate to ensure it gets drawn in.

Others may know better ...

My Mercedes has "afterblow" feature. It runs the fan after the vehicle is shut off to achieve similar drying/warming that I suggested.

spaceghost2000 · June 10, 2016

Same thing, taking mine into the dealer next Friday.

bigsam94 · June 10, 2016

Hmm. I didn't have any luck finding anything on afterblow in my truck. I too have been noticing a smelly AC system.

Been also meaning to replace the cabin air filter.

found this in another thread:

Afterblow

Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned OFF. This reduces the amount of microbial growth that can create undesirable odors. The vehicle does not come equipped with the afterblow feature turned ON. If the afterblow feature is required due to an odor concern, it must be enabled using the scan tool Afterblow configuration function.

After the HVAC control module has been programmed for afterblow, the following conditions must be met for afterblow to operate:

The engine has been turned OFF for at least 30 minutes.
The ambient air temperature is at least 21°C (70°F).
The A/C compressor operated for more than 2 minutes before shut down.
The system voltage is at least 12 volts.

Once the above conditions have been met, the blower motor will perform the following sequence up to 5 times. This could last up to an hour:

The blower motor will be OFF for 7–11 minutes.
The blower motor will RUN for 25–30 seconds.

fondupot · June 10, 2016

found this in another thread:

Afterblow

Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned OFF. This reduces the amount of microbial growth that can create undesirable odors. The vehicle does not come equipped with the afterblow feature turned ON. If the afterblow feature is required due to an odor concern, it must be enabled using the scan tool Afterblow configuration function.

After the HVAC control module has been programmed for afterblow, the following conditions must be met for afterblow to operate:

The engine has been turned OFF for at least 30 minutes.

The ambient air temperature is at least 21°C (70°F).

The A/C compressor operated for more than 2 minutes before shut down.

The system voltage is at least 12 volts.

Once the above conditions have been met, the blower motor will perform the following sequence up to 5 times. This could last up to an hour:

The blower motor will be OFF for 7–11 minutes.

The blower motor will RUN for 25–30 seconds.

Thanks, so it's something that needs to be programmed into the truck. It's not there from the factory.

bigsam94 · June 11, 2016

Thanks, so it's something that needs to be programmed into the truck. It's not there from the factory.

not trying to split hairs, but i think it is "there" so to speak, the dealer just has to turn it on. Next time you are there for anything mention it to the service writer and i'm sure they will turn it on for you for free, thats what i plan on doing and it cant take them more than 10 minutes.

crankman · June 11, 2016

I had thie happen on my 2007 silverado work truck, ran it it to my dealer and they said its a easy fix. Never smelled it again. Sorry dodnt know what they did but it had a nice clean cold smell coming out of the vents ever since.

phabejhmoob · July 19, 2018

Mine's doing that recently, scheduled to be taken. What are the results? fixed by dealer?

TXGREEK · July 19, 2018

Mine's doing that recently, scheduled to be taken. What are the results? fixed by dealer?

Change your in cabin air filter every year.

Research on YouTube on how to. Here’s the one I use on both my GMC’s and never have a musty/stinky smell. If you don’t change it out then the mildew/mold sets in onto the inner hoses requiring sanitizing.

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swathdiver · July 19, 2018

Afterblow on the GMT900s is turned on via the Tech2. The K2s are serviced with the MDI/GDS and Afterblow is probably turned on by that tool.

jagabom (Esquire) · July 24, 2018

Good idea.

ShamrockShooter · July 24, 2018

Can't you just turn the vent on recirculate air from inside and spray some Lysol into the air intake under the glove box? Just guessing here but I think I remember that was the procedure on my wife's Honda.

I tried replacing the cabin air filter but the moldy smell persists. I always forget to turn off the AC 5 minutes before I turn off the car to let it dry out.

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