A/C suddenly smells terrible!

[WhereRU_A-A-Ron]

So yesterday I drove my Jeep, A/C was going the whole time, no issues. I get in this morning and crank her up and almost immediately everything smells like moldy cheese and I mean EXACTLY like moldy cheese. My two boys are about ready to bail.

I pull the cabin air filter and it’s really clean and doesn’t smell like anything at all actually. No excessive debris or signs of freeloaders. Okay… so I check below the windshield to see if something got spilled there and it’s picking it up on the way in; nothing. Garage doesn’t smell like this at all.

I dropped my kids off and then turned it back on and eventually it subsided. However, every time I’ve gotten back in today it’s the same tune - stinks for a few minutes then goes away.

So now I’m stumped… HOW DO I GET RID OF THIS SMELL?!

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[TheBirdie72]

 

[mwilk012]

Clean the evaporator, and make sure there isn't a dead mouse in there anywhere.

 

[MikeyK]

07 FJ Cruiser always had a mouse nest in the dash or engine compartment around this time of year ?

 

[PhoenixM3]

Most likely a condensate drain is plugged.

Also, if Wranglers are prone to this issue, it really does help to shut the AC off a minute or two before stopping
and shutting off the engine. This does help minimize that sour dishrag smell. Coincidentally, “Sour Dishrag Smell“ is the name of my new band.

 

[jeepdabest]

I hope it isn't the evaporator. It's under the dash near the heater core and they have to take your whole dash apart. Check to make sure your carpets in front arent wet.

 

[jjvincent]

Make sure the AC drain is not plugged. It might be (or really restricted) and then old stagnant water sits inside and thus you get stinky time.

On the other hand, the funniest thing I have ever read in a diagnostic for smells for the AC unit was from Ford. It listed "wet cement smell" as water buildup on the evaporator.

To finish, we had a Mazda CX9 in and the customer complained of a grinding noise when turning left. Thus, you think things like a wheel bearing. Nope. It was the AC drain was plugged and it was that when you turned left, the water wooshed over to the blower motor and it sounded like a paddle wheel. Swerve the car back and forth, it sounded like the ocean. When I unplugged the AC drain, I got just over 2 gallons of water that was sitting in there.

 

[WhereRU_A-A-Ron]

I hope it isn't the evaporator. It's under the dash near the heater core and they have to take your whole dash apart. Check to make sure your carpets in front arent wet.

Okay yeah that sucks so second that. Don’t think the carpets were wet but I’ll check.

 

[WhereRU_A-A-Ron]

Love the suggestions! Thanks! I’ll report back if I find anything. Open to more suggestions as well.

 

[roaniecowpony]

Okay yeah that sucks so second that. Don’t think the carpets were wet but I’ll check.

If it smell like old gym shoes, it's the evaporator. It has built up some mildew. There are commercial foams that are intended to clean the evaporator. Getting the foam on the evaporator is the hard part. If drilling a hole in the HVAC housing is necessary, it's worth it in the long run. But be careful.

 

[TheBirdie72]

If it smells that bad, I’d say “light a match” but… ?

 

[WhereRU_A-A-Ron]

Anybody got a picture of the drain location? Google isn’t helping much right now. Everything coming up is about the floor drain plugs.

 

[PhoenixM3]

Q

Anybody got a picture of the drain location? Google isn’t helping much right now. Everything coming up is about the floor drain plugs.

I don’t have my Jeep yet, so I’m guessing here…. Have you checked for any debris near the hood cowling near the base of the windshield? There must be some area that may have clogged and failed to drain properly. I suspect residual moisture has formed mildew in/or around the ventilation inlets, or out of sight on/near the AC evaporator coil. Locate and remove your cabin AC filter and change that too. Good luck and keep us posted!

 

[roaniecowpony]

It's very common for evaporators to build mildew and mold, since the evaporator gets condensation all over it every time the A/C is used. It's a well known problem. Lots of videos on it for cars and your home A/C.

But yes, it could also be excerbated by a clogged drain. Pouring a bit of water in the HVAC intake at the base of the windshield should result in it draining out of the pinch weld.

 

[rkwfxd]

Just happened in my wife’s Tahoe. I changed the cabin filter behind the glove box. Super easy on JL, pretty much a PITA on the Tahoe. Anyway, the smell went away.

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