A/C Stinks at Start Up

T-Town-Z · June 10, 2015

I've noticed it pretty much since my truck was new, but this summer, when I start my truck, the smell of the air is really nasty. Now that it's hot and humid again, the A/C just smells putrid - stagnant for the first few minutes after starting it up. Kind of like an old, damp musty pair of running shoes. I was going to change out the cabin air filter to see if that helps, but figured I would let the dealership investigate it when I get my next oil change (if I can stand it that long).

Is anyone else having this problem ? Anyone found a cure for it ?

BigBadSierra · June 11, 2015

Turn the AC off just before you stop/park it for a lng period of time.

Just run it until warm air strats going through it.

The smell comes from the cold moist air staying in the system.

Just blowing it out helps.

It seems to be worse if you park in a garage as the cool air stays in the system longer.

Spurshot · June 11, 2015

This is a common issue across many makes of vehicles. GM has a spray can of disinfectant you can buy. You run the AC at wide open (manual) and spray into the inlet at the base of the windshield. Lysol works too. But get the unscented or some lightly scented type. Otherwise you'll hate the smell even more.

Here's another from some good guys on AC Kits. They have a forum worth keeping in mind. http://www.ackits.com/product-categories/evaporator-core-treatments-odor-removal

Some on Amazon. http://www.amazon.com/s/ref=nb_sb_ss_c_0_8?url=search-alias%3Dautomotive&field-keywords=ac+odor+treatment&sprefix=ac+odor+%2Caps%2C213

The foaming types are the best for cleaning really badly fouled ones.

haider320 · June 11, 2015

Turn the AC off just before you stop/park it for a lng period of time.

Just run it until warm air strats going through it.

The smell comes from the cold moist air staying in the system.

Just blowing it out helps.

It seems to be worse if you park in a garage as the cool air stays in the system longer.

What he said. Just check your cabin filter, don't wait for the dealer. It's an easy check.

Payton34 · June 11, 2015

I had this and the dealer said their was a TSB and had to order some parts. I had it fixed couple months ago and AC has no more funky smell.

T-Town-Z · June 12, 2015

I've owned a lot of vehicles over the years and its surprising to me how bad this one smells ! And its only a year old ! Thanks for the suggestions. Looks like I'll try one of the products that I saw on Amazon since they have much more selection than the local auto parts place... I'll reply back with my results in a week or so.

oldscsc · June 12, 2015

Condensation is created when air is cooled and hangs around on the evaporator, where the hot-to-cold transition takes place.

If you run the A/C until you shut the pickup off, the condensation lingers on the evaporator fins. Keep in mind that the HVAC box where the evaporator lives is a damp, dark place. Mildew has a hay day on the evaporator core if you allow it to stay damp.

The best method to alleviate this concern is to install an afterblow module, which typically runs the blower motor for 30-60 seconds after the pickup is turned off. This ambient airflow is normally sufficient to dry the evaporator. I believe afterblow modules have been a field fix for this concern on past GM models.

As mentioned, you can accomplish the same thing by turning the A/C off and circulate fresh air for approximately a minute before reaching your destination.

GMC-AT · June 12, 2015

don't use the recirculate mode on your AC... will help...

20L8TSierra24 · June 12, 2015

Changing oit the cabin air filter might help the stinkage as well

SouthernSilveradoGuy85 · June 12, 2015

This is my 3rd Chevy truck and I've never had that smell and I don't have any friends that had that issue either. It's probably just something somewhere in the ducting or just somewhere in the system since it was doing it since it was brand new. I've left the A/C on all the time in any truck when turning it off and no smell even after running it full blast.

Spurshot · June 13, 2015

What it amounts to is bacteria is growing on the evaporator where the inlet air is flowing over to be cooled. The bacteria is from airborne organisms in the air landing on the evaporator and then the condensation feeding moisture to it. Generally, drier conditions don't facilitate it well.

therink · June 13, 2015

As mentioned above, pull your cabin filter and check it. It is located behind the glove box. I bet it is full of mold. Easy fix.

Search amazon. About $15.

Spurshot · June 13, 2015

If you get on some AC forums you'll get some direct experience from guys with a lot of years doing this. Bacteria is growing on your evaporator because it gets wet everytime you use the AC. You need to clean it and kill the bacteria. If you aren't up for doing it, take it to an AC shop. They'll have the foaming cleaners and get it cleaned up. It just gets progressively worse as time goes on. Best to address it sooner than later. It should get done on an annual basis, more or less, depending on your experience/environmental conditions. Lots of heavy pollens seem to be a contributor as well as humid climate..

Spurshot · June 13, 2015

cleaners that have been popular.

http://www.dwd2.com/

http://www.summitracing.com/parts/lbg-96030?seid=srese1&gclid=COy0gpzljMYCFZNefgodTj8AWg

http://www.zoro.com/simple-green-coil-cleaner-aerosol-20-oz-white-0110001213418/i/G6223725/?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CKqCrsnljMYCFUeTfgodgmUA0w&gclsrc=aw.ds

How to youtube

https://www.youtube.com/watch?v=0iD_lEz6z78

Link to a forum post on this.

http://www.autoacforum.com/messageview.cfm?catid=2.&threadid=18586

The article above mentions some GM vehicles having the blower motor run for 5 mins after shutdown. I think this was a TSB or other doc in the old GMT800 or 900.