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HVAC smell

autocomman

Buick Newbie
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Buick Ownership
Buick
Anyone notice a musty smell in the AC after turning it off and leaving the blower on? Yes I've replaced the cabin filter, and the car is not dirty, 2019 15k miles.

Is GM using some kind of cleaning solution to deal with this in other cars? I do not want a dealer removing the dash and hvac unit to deal with this smell. It was a problem when I worked at VW and there were cleaning solutions you pump into the evaporator box. Thoughts?
 

RegalMN

Active member
128
76
28
Minnesota
Buick Ownership
'18 Regal Sportback Essence
Anyone notice a musty smell in the AC after turning it off and leaving the blower on? Yes I've replaced the cabin filter, and the car is not dirty, 2019 15k miles.

Is GM using some kind of cleaning solution to deal with this in other cars? I do not want a dealer removing the dash and hvac unit to deal with this smell. It was a problem when I worked at VW and there were cleaning solutions you pump into the evaporator box. Thoughts?
It happens in every car I've ever had. If it gets too bad you can buy cleaners to run thru with the AC on. They have worked pretty well for me.
 

FavaBean

Well-known member
695
469
63
DE
Buick Ownership
2018 Regal TourX Essence
No smells yet.... but after running the A/C, I try to dry out the insides of the vents by turning the A/C off and just blow air through it for about a min before reaching my destination. Even got my wife to start doing it in her car. Seems to help with odors in the ducts.

You can try opening the hood and spray Lysol [EDIT - see post #5 may be flammable] (or maybe Fabreeze) in the vent intake in the hood cowl. I'd remove the cabin filter prior to spraying. Cycle through the different settings to distribute through the various ducts. Good luck!
 
Last edited:
84
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Hamilton, New Zealand
Buick Ownership
2019 Holden ZB Commodore RSV Liftback 3.6 AWD
There is a simple solution to this problem which I use. Turn off the A/C about a minute before you stop the engine on the last trip of the day. Note, I am only turning off the A/C portion of the HVAC system.

This allows time for any condensation from the evaporator to drain away. I leave the ventilation fan running while doing this as I think the extra flow from the fan helps expel the condensation.

If there's no moisture left lying in the HVAC system there's no smell.

Edit: While I was typing my reply I see @FavaBean as given the same advice.
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Sael

New member
7
4
3
Buick Ownership
2018 TourX
You can try opening the hood and spray Lysol (or maybe Fabreeze) in the vent intake in the hood cowl. I'd remove the cabin filter prior to spraying. Cycle through the different settings to distribute through the various ducts. Good luck!
I can tell you from experience not to do this with the vehicle running and the fan blowing. Apparently the propellant in Lysol is highly flammable, I did this years ago with a Dodge van and poof, a small explosion and big flame from the intake vent. I happened to have a hose right there and sprayed down the vent, fortunately there was no damage.
 

RegalMN

Active member
128
76
28
Minnesota
Buick Ownership
'18 Regal Sportback Essence
I can tell you from experience not to do this with the vehicle running and the fan blowing. Apparently the propellant in Lysol is highly flammable, I did this years ago with a Dodge van and poof, a small explosion and big flame from the intake vent. I happened to have a hose right there and sprayed down the vent, fortunately there was no damage.
You can use this instead:

I've used it and it works pretty well.
 

2007LucerneCXL

Full Member
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Illinois
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2007 Lucerne CXL. and 1995 Lesabre currently, past 1973 Riviera, 1968 Riviera
Check out other GM vehicles as a Reprogram HVAC Control Module to Enable Afterblow Function has been used. There are TSB that deal with the musty smell on many GM vehicles that include reprogramming, coil cleaning with approved chemicals and component replacement lots of available solutions but what would apply may be something to cover with GM or their tech support, dealers may be the route to start the inquiries.
 

PrincipalDan

Well-known member
1,044
860
113
Gallup, NM
Buick Ownership
2018 Regal TourX
I never use "recirculate" setting. That just seems to promote that "swamp a$$" smell developing as quickly as possible. My wife bought a 2016 Terrain brand new and by the 2nd summer it smelled like a sewage treatment plant when the A/C was running. I had to retrain her that you didn't need to run the A/C on MAX & recirculate 99% of the summer. You could get hot air out faster by opening the windows, driving a short distance, and then using regular AC while the windows were rolled up.

Used to chafe my behind that my Toyota automatically engaged recirculate if you dared to turn the dial all the way to cold.
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1500cc

Active member
223
110
43
Ontario
Buick Ownership
2018 Regal GS
I had this happen in my C6. A mechanic with the right scan tool can turn on "after blow", which turns the fan on for a minute or so about 30 minutes after you shut the car off. Same principle as manually turning the a/c off before you reach your destination like mentioned above, but of course it's automatic. It probably killed 80% of the odour for me. I also did the Lysol thing which helped some too.

My ATS also had this problem, the dealer did a bunch of things including installing a ozone generator, but it cut the smell only by about 50% at best and I just had to live with it

Also make sure your evaporator drain isn't blocked; easiest way is to just make sure you see it dripping on the driveway when the a/c is running.

I think that once you have a car with this problem, it just 'embeds' itself and you'll never totally get rid of it.
 

autocomman

Buick Newbie
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28
Buick Ownership
Buick
I know bout the afterblow function, but I would have thought that's just turned on, guess it's not by default? I never payed enough attention to it. I switch between recirc and fresh air. Half the time in LA you get stuck behind someone's smelly junk and I don't feel like breathing it. Or a smoker with the windows down. I also have tried to run the blower ac off a min or so before I park the car if I've had the ac on. Guess I'll look into some of the cleaning products, and the next visit to the dealer for the inevitable infotainment update (if it's ever released), the creaky strut mounts and squeaky brakes I'll mention the smell and afterblow.
 

buickbox

Member
36
20
8
Buick Ownership
2018 Regal Tour X Preferred
you can try gm acdelco odor eliminator, treat your car on full ac with ozone generator in car for a day and swap a new cabin air filter. Mine has smell and now it is all gone. If you spill something on the carpet, wet vacuum it using Home Depot rental detailer.
 

ItsDeke

New member
4
1
3
Buick Ownership
TourX
I think I’ve been running into this the last couple days and it’s weird. I’ve only had the car a few months (2019, 22k miles) and there was never any smell before. I guess the heat and humidity have had the AC working over time and it caused it to get funky? Like it borderline smells like BO. That said, I’m currently sitting in the car typing this with the AC off and the blower on, and I think it’s a lot better already. If this is the fix that’s not a huge deal in the grand scheme of things, but what a weird design flaw that I can’t say I’ve encountered in any other cars.
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RegalMN

Active member
128
76
28
Minnesota
Buick Ownership
'18 Regal Sportback Essence
I think I’ve been running into this the last couple days and it’s weird. I’ve only had the car a few months (2019, 22k miles) and there was never any smell before. I guess the heat and humidity have had the AC working over time and it caused it to get funky? Like it borderline smells like BO. That said, I’m currently sitting in the car typing this with the AC off and the blower on, and I think it’s a lot better already. If this is the fix that’s not a huge deal in the grand scheme of things, but what a weird design flaw that I can’t say I’ve encountered in any other cars.
Mine went through a phase this spring when I was switching a lot between AC and no AC. Now that summer is in full swing and the AC is on all the time the smell went away.
 
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