Sour smell coming from vents

[Kyle]

So my fiancé's 09' impala has this horrible sour vinegar smell coming from the vents when you turn on the air. I've used sprays, replaced filters, attempted to swab as much of the hvac system I could, and I've also tried a combo of spray and running the Heater for over an hour to try get the ducts hot enough to dry out any mildew that could be hanging around... I'm about exhausted with ideas now.. The smell may go away for a week or so once I've tried something, but it comes back...angrier each time....

Anyone have any experience with this? Any suggestions or ideas are appreciated. I'm trying to avoid taking it in anywhere

 

[karlac]

No expert, but solved the problem in my wife's Lexus by making sure the AC was not in recirculating mode, and was using fresh outside air. Took a while, but it quit smelling, as long as it was not always automatically recirculating. Cheap to try in any event.

 

[Savage20]

put the air on Recirculate then spray some Lysol under the dash where it intakes the air. voila!

keep your face away from the exhaust vents when you do this. lol

 

[TexMex247]

I am an expert, this is what I found doing some brief research. Your car does list a cabin air filter that is serviceable and accessible through your fresh air cowl. That is basically the plastic trough below your front windshield. To gain access you have to turn off the key while running your wipers in an up position, then remove a sectional plastic cover. That is your best starting point. You should also verfiy that condesation is properly draining from the evaporator core housing and not creating mold by standing in the HVAC housing.
From there, GM actually adresses this problem using a "deodorizing kit". If you buy one from them, it will hopefully include instructions. If it doesn't, you basically have to unplug your compressor and run the heat on high for 10 mins or more to dry the evaporator core. Next, you punch a small hole in your duct work close to the evaporator housing and spray the deodorizer in short bursts, toward the core. It's tricky to find a spot upstream of the blower motor that will circulate the spray onto the core. It honestly seems simpler to do it through the fresh air cowl with the cabin air filter removed.
Anyhow, hopefully you just have a dirty cabin filter and that's the end of it. Otherwise, using the spray and properly apllying it seems like a complete pain in the ass even for an experienced tech. Best of luck.

 

[Kyle]

No expert, but solved the problem in my wife's Lexus by making sure the AC was not in recirculating mode, and was using fresh outside air. Took a while, but it quit smelling, as long as it was not always automatically recirculating. Cheap to try in any event.

She has been keeping it on fresh air for over 2 months now, with no improvement unfortunately :/

put the air on Recirculate then spray some Lysol under the dash where it intakes the air. voila!

keep your face away from the exhaust vents when you do this. lol

I've actually done that, it works for a few days and then comes back.. I did unfortunately blast myself with Lysol though. Haha

I am an expert, this is what I found doing some brief research. Your car does list a cabin air filter that is serviceable and accessible through your fresh air cowl. That is basically the plastic trough below your front windshield. To gain access you have to turn off the key while running your wipers in an up position, then remove a sectional plastic cover. That is your best starting point. You should also verfiy that condesation is properly draining from the evaporator core housing and not creating mold by standing in the HVAC housing.
From there, GM actually adresses this problem using a "deodorizing kit". If you buy one from them, it will hopefully include instructions. If it doesn't, you basically have to unplug your compressor and run the heat on high for 10 mins or more to dry the evaporator core. Next, you punch a small hole in your duct work close to the evaporator housing and spray the deodorizer in short bursts, toward the core. It's tricky to find a spot upstream of the blower motor that will circulate the spray onto the core. It honestly seems simpler to do it through the fresh air cowl with the cabin air filter removed.
Anyhow, hopefully you just have a dirty cabin filter and that's the end of it. Otherwise, using the spray and properly apllying it seems like a complete pain in the ass even for an experienced tech. Best of luck.

I've taken that cowl off, replaced the filter and used that spot to directly blast the deodorizer and I have run it with the heat on high for quite a long time. It worked for about a week and then came back even worse...

I have excellent drainage from the evaporator core and I've gone as far as to dismantle the blower and and swab the duct work hoping to pull back something. Clean as a whistle. Next step will be to trade in the car and make it someone else's problem...

 

[shortround]

It is the smell of Government Bail-Out money and it will never go away.

Be well.

 

[Charlie]

Just buy here a new car, damnit!

 

[Phogot]

Also try ac evaporator foam cleaner that comes with a long hose to put in the drain tube under the car, check YouTube and Amazon. I did it on my odyssey van and made a big difference

 

[Whistler]

Mrs. Whistler's HHR had a sour smell, it was caused by a leak right at the bottom of the windscreen allowing water to get into the cabin air filter. If it rained a lot the passenger floorboard would be damp. Fixed the leak, replaced the cabin air filter (again), no more smell.

I know you said you replaced the cabin air filter, so did I but it did no good until I found and resolved the leak.

 

[ed308]

Mrs. Whistler's HHR had a sour smell, it was caused by a leak right at the bottom of the windscreen allowing water to get into the cabin air filter. If it rained a lot the passenger floorboard would be damp. Fixed the leak, replaced the cabin air filter (again), no more smell.

I know you said you replaced the cabin air filter, so did I but it did no good until I found and resolved the leak.

I'm thinking a leak as well. Also wondering if mold is the causing the odor. If you fix the leak, the water will eventually evaporate and the mold will stop growing and go dormant. But I would get rid of the mold if you can find it. Just wipe the area with a rag soaked in bleach and that should kill any mold found.