AC smell when first turned on

[21denali62]

Hi All,

Just got a new to me 21 Yukon Denali Ultimate with 28k miles and so far loving it. Noticed a funk smell when first turning on the AC. Figured it must be mold/mildew in the vents or a clogged ac drain line. Otherwise ac works just fine.

I did one of the vent treatments to kill of the mold and changed the cabin air filter just to be sure. Still a small smell when first turning ac on. Figure the ac drain line must be clogged. Anyone have a photo of the drain tube location so I can try to blow some air into it? Or should I just take it to dealer since it has a few months of factory warranty left?

TIA

 

[OR VietVet]

Welcome to the forum.

You said, "Still a small smell", so must have gotten better and on the right track. The drain is on the engine side of the firewall and likely up above the exhaust pipe on the passenger side. Do not blow air up in to it. Whatever is still trapped there will be blown in to the evap case. Take a small section of coat hanger and leave a slight bend at the end of it and stick up in there just a very little at a time and wiggle/twirl it to free up the clog. If you feel something hard with it, do not push harder. I would also do another vent treatment and when you use it next, especially on a humid day, crawl under there, while it is idling with a/c on, and look for that water to flow freely. I would bet you can locate the drain the same way because if was completely clogged, the inside floor could get wet.

I am a bit surprised that this problem is there, this early in it's life.

 

[Micahsd]

Curious how you make out on this as my ‘21 Tahoe is doing the same. I did use one treatment of the BG Frigi Fresh product in the vent intake area above the firewall/below the wipers area and while it improved a little it’s still there.

 

[21denali62]

Welcome to the forum.

You said, "Still a small smell", so must have gotten better and on the right track. The drain is on the engine side of the firewall and likely up above the exhaust pipe on the passenger side. Do not blow air up in to it. Whatever is still trapped there will be blown in to the evap case. Take a small section of coat hanger and leave a slight bend at the end of it and stick up in there just a very little at a time and wiggle/twirl it to free up the clog. If you feel something hard with it, do not push harder. I would also do another vent treatment and when you use it next, especially on a humid day, crawl under there, while it is idling with a/c on, and look for that water to flow freely. I would bet you can locate the drain the same way because if was completely clogged, the inside floor could get wet.

I am a bit surprised that this problem is there, this early in it's life.

Thanks for the reply. Agreed that it did get better. I did a second treatment today. After I drove around doing errands I can home and saw it was definitely draining on the garage floor. I'll let you know if it follows up.

Is it just the one drain above the exhaust? That is where it was coming from and heard the sizzle for the small amount that hits the section of exhaust pipe.

 

[21denali62]

Curious how you make out on this as my ‘21 Tahoe is doing the same. I did use one treatment of the BG Frigi Fresh product in the vent intake area above the firewall/below the wipers area and while it improved a little it’s still there.

I'll let you know for sure. Who knows if the owners before me had pets, etc.

The first time around I used microban (Lysol would work too) in the vent you mentioned. Feel like it is designed to kill mold/mildew better. I also used a small amount of the armor all product made for vents when I did it.

This time I did the full cab treatment for vents that AC pro makes. I did half into the vents under the hood and let it run. It then has you spray the other half directly into the vents inside the car. After you let it run with windows open for 5-10 minutes.

I'd recommend trying the microban in the outside vent and letting it run through. After a day or so try the ac pro treatment. I swapped my cabin filter after the first treatment.

I'll let you know in a few days how it's doing.

 

[OR VietVet]

If it is dripping then drain is not clogged or just partially clogged. May be some info out there for this new of a vehicle having this problem.

 

[21denali62]

If it is dripping then drain is not clogged or just partially clogged. May be some info out there for this new of a vehicle having this problem.

I'll circle back in a few days and see if the second treatment did the trick.

On a side note, based on your username name, thanks for your service. I'm an Army vet myself , Afghanistan.

 

[OR VietVet]

I'll circle back in a few days and see if the second treatment did the trick.

On a side note, based on your username name, thanks for your service. I'm an Army vet myself , Afghanistan.

Thank you for your service and thanks for your comment about mine.