Chevy garbage – stinky AC

Chevy made awesome trucks, I had a friends 04 Go 300k miles on original trans and motor and was still going when he sold it . The first gens of duramaxs with allisons awesome trucks . Multiple people I know had eras of that truck and trans go 100s of thousands and thousands of miles… but lately.. Chevys been irritating the hell out of me .

I have had company vehicles (all Silverado’s) for the last 10 years. 30-40 k miles a year I put on . As of 2015-16 EVERY chevy truck Ive owned has the AC compressors start to smell like wet dog . Almost all my coworkers have the same issue. They are good for the first half of their life, but now it smells like a combo of wet dog and dog poop . Anyone else have this issue find a fix ? Ive brought them to the dealers and they spray some disinfectant spray on and it fixes it for a few months but usually its back to square one. Also changed the cabin air filter which looks like new. Lots of posts online but very few fixes. Anyone else experience this ? I have a 99 Ford with factory AC that mice live in half the year that smells better.

Dont get me started on the giant touch screens and carplay either .

Honestly we haven’t had any in the shop that I can think of with that issue. They sell filters that have a scent built in. I have smelled lots of older cars in the past that smell like your talking about though. I would have thought you would have been complaining about there terrible transmissions.

I wonder if an ozone generator would help. I used one to get a musty smell out of my topper carpet a few years ago. No smell since.

Considering every Chevy work vehicle we’ve had the last decade has leaked oil like a sieve, perhaps it’s the least of your worries?

John Rasmussen wrote:

Honestly we haven’t had any in the shop that I can think of with that issue. They sell filters that have a scent built in. I have smelled lots of older cars in the past that smell like your talking about though. I would have thought you would have been complaining about there terrible transmissions.

Ive had one tranny out (forgot cant use the word tranny to describe transmissions anymore lol ) and one fuel pump go out . The tranny went out due to a cracked line leaking oil. Havent had one longer than 90 k miles.

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Moisture from the heating core builds up in certain cars. Check for a drain hole that might be plugged.

I know many GMs from that era had condenser issues due to a weak weld point cracking. I had a 2015 Sierra that had a bad condenser which I replaced with a newer version.

Not likely why you’re having an issue. I would check the evaporator drain, maybe it’s clogged.

Always check and maintain your vehicles cabin air filter. They trap all types of contaminants and materials that can keep your HVAC system from not functioning properly and can cause some pretty funky smells as they start to decompose.

isu22andy wrote:

I have had company vehicles (all Silverado’s) for the last 10 years. 30-40 k miles a year I put on . As of 2015-16 EVERY chevy truck Ive owned has the AC compressors start to smell like wet dog .

More info is needed. You can’t ever smell an AC compressor because the compressor is compressing refrigerant gas in a closed system. What you’re smelling is outside air that is passing through something rancid on it’s way to the cab.

First off, are you only smelling wet dog when the AC is on? Or does it also smell that way when the heating is on as well?

If AC only, here’s what I’d check:

1. Have you checked and changed the cabin air filter? What did it look and smell like? Was it wet?

If you’re doing 30-40k per year you should be changing this filter at least yearly.

2. Clean and disinfect the evaporator coil. Again, important to note what it looked and smelled like to know if this was the problem.

3. Check and unclog the evaporator drain pan and line. In the summer, you will usually know you’ve found the problem if it’s the evaporator drain because about a gallon of putrid, rancid water that smells like dog sh!t will come dumping out on your garage floor when you unclog it, but this time of year without running the AC too much, you may not have the buildup of gross water in the evap pan and drain. I’d test the drain by pouring water in and seeing if it runs out by the drain line. Again, disinfect the entire pan and drain with high quality disinfectant.

If you’re smelling wet dog with the heat on, you may have a different problem. Any signs of mouse infestation like mouse nests, turds, etc?

I’ve pulled the cabin air filter at least 10 times in all these different vehicles . Usually they look and smell brand new . Replacing them regardless does nothing . It’s usually upon start up when the ac is running and will go away after running a few minutes .

You’re right I probably do need to do the disinfectant fix – but on brand new 1-2 year old trucks I’d sure think I’d expect more . I’ve taken it to the dealer to do it but it’s a temporary fix . More or less frustrated they can keep sending brand new vehicles out like this . Seems crazy .

When it comes to cabin filters some are just paper filters and you can upgrade with an available charcoal filter for odor control.

Check for wet carpet around the heater area.

Okay so that establishes that it’s probably not the cabin air filter. But…

isu22andy wrote:

You’re right I probably do need to do the disinfectant fix – but on brand new 1-2 year old trucks I’d sure think I’d expect more . I’ve taken it to the dealer to do it but it’s a temporary fix .

The dealership fix is temporary because they haven’t found the real problem would be my thought. Unfortunately you or an actual mechanic needs to be able to physically look at the evaporator coil and the area under the coil that catches all the condensation.

In my opinion this diagnosis is easier in the summer when the air conditioner has been used a lot. Then it’s totally obvious what’s going on because there’s going to be a lot of stinky water in the area below the evaporator that catches the condensation if the drain is clogged.

The other thing to look at, and this is really gross, is might you have a mouse that’s built a nest somewhere in the air system? Now most of us know what mouse pee smells like and in my opinion your description sounds more like something wet and moldy. I’m just throwing out other options here. You should have seen the rancid mouse nest that I dug out of the neighbor’s car. Freaking gross.

I’m with Tom, look for moist carpet. Also Take off the plastic floor moulding under the door in the cab. I had a bad weld that leaked onto the carpet and had that smell.

My 2016 silverado had a bad seal where the a/c lines went through the fire wall. Causing the carpet and pad to retain water. Mold and dog $hit smell. Main motors fixed under warnnity. Two them 2 months to get parts had to take the dash apart. Every two weeks I was getting a new loaner cause the6
Didn’t run the miles up on there loaner.

Thanks for this post!!!! Been a Chevy guy all my life. Have owned 6 brand new ones since I’ve been 21. Latest a 2021 3500 High Country about a year in started smelling literally like I thought the kids stepped in dog $hit. I have searched high and low. Had it detailed twice since I’ve owned it. Once the perfume wears off the smell comes back. I started to think it’s the leather? Probably not though if your WT’s are having the same issues. Pic is of my work truck. Mechanic failed its first DOT inspection. I got an email about something in the front end being “misaligned”. Went into garage to find out what the hell is wrong with my brand new truck. Should have known the ford guy didn’t like my modification. lol. I told him I didn’t want my neighbors talking.

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Try turning off the a/c (and defrost) and putting on vent 5 minutes before you shut off the vehicle. This will dry out the evaporator, reducing the amount of moisture in it.
Did I mention defrost is running the a/c?

2019 1500 100K + miles – no issues with mine.

I have a 2015 Colorado with the same issue. Cabin air filter change does nothing to fix it. Only with the AC not the heat/vent. Also, it’s only for the first few minutes of the AC running, then you don’t notice it. I had written it off to years of hauling sweaty kids for youth sports and their funk seeping into the interior, but they’re leather seats, And if it was the interior it would always smell, and not just the first few minutes of air. I will check the evaporator drain, that’s something I hadn’t thought of.

I had a similar problem and did Brandymans process.
Worked like a charm. Was told the moisture from the AC was what was stinking. If you run the vent for 2-5 minutes before shutting it down it worked great – no smell. And yes, once the vehicle was running for a while with the AC on the smell went away. About 3 blocks from my house I would turn the AC off and the fan to high.

Have a 2017 Impala. Same issue.

2005 Silverado 1500, 180,000 miles and no smell. 2015 Silverado 1500, just under 100,000 miles and no smell.

I guess it turns out that modern GMs stink in more ways than one…

3rdtryguy wrote:

I’m with Tom, look for moist carpet. Also Take off the plastic floor moulding under the door in the cab. I had a bad weld that leaked onto the carpet and had that smell.

Is the smell caused by wet carpet and leaks present all the time?

Just wondering because OP says the smell only present when he’s running AC. Which is why I suspected evaporator and drain issues.

We have a 2019 Dodge van and I had no idea that there was a cabin filter in the thing. We had an oil change done and was asked if we wanted that cabin filter changed and I asked to look at the current one and got an eye full. New filter and the van’s interior smells 100% better.

Evaporator and humidity in the vehicle. Roll down windows and turn on vent before putting away as often as possible.

I have had a new 1999 2002 2005 2007 2019 & 2022 non of them have ever had stinky a/c.

To be fair this truck sees alot of gravel and corn fields so likely could be a plugged drain. Ive found some links on where to find them … Doesnt look like an easy access to find . Im still rather annoyed of why all the old vehicles have 0 issues with this problem…

https://www.gm-trucks.com/forums/topic/240608-clogged-ac-drain/

Much easier on a hoist, if I can help the shop is in Ham Lake. Let me know.