Help locating AC drain 2021 GMC Yukon xl Denali 6.2l 4wd

BamaJamma87 · June 9, 2023

Trying to locate the main AC drain on my 2021 Yukon XL. I have a musty smell when first starting the vehicle. I have cleaned out the rear drain but cannot locate the main ac drain. There is water that is soaking up on the transmission heat shield and dripping off the bottom of the transmission. And help would be appreciated.

is this the ac drain??? Located underneath on the passenger side.

mjm-1957 · June 9, 2023

That is the starter you are circling.The water you are seeing on the transmission is from the ac drain. It is above the trans and drips right on top of it. Another brilliant idea from GM.

BamaJamma87 · June 9, 2023

Dang… well that is incredibly inconvenient. Is there any way to get to the AC line to check for clogs? I can’t even see it from underneath.

mjm-1957 · June 9, 2023

If you see water dripping on the transmission case chances are good that the drain is clear.When you shut off the truck the water lays in the blower case after the blower motor stops pushing air threw the evaporator. There are evaporator cleaning chemicals that are sprayed threw the intake vent under the hood at the base of the windshield that are supposed to help with the smell. There was also an afterblow calibration that was available and would keep the blower motor circulating air threw the evaporator to try and dry it and force the water out of the blower case. Have the dealer see if there are any TSBs relating to your complaint.

KARNUT · June 9, 2023

I don’t think it would be a problem on a vehicle with automatic climate control. Sometimes keeping an AC in max recirculating can cause a musty smell. By not allowing outside air to flow through the AC.

newdude · June 12, 2023

Drain is right on the firewall above the transmission. Probably can't really get to it without pulling the right front wheel and the wheel liner, or the liner at a minimum.

I'd check the cabin filter as well and replace it if dirty.