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

[BamaJamma87]

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]

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]

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]

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]

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]

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. 

 

Edited June 12, 2023 by newdude

[Jr1985]

What is the hose size for the ac drain? I would like to add an extended hoze but I need the width dimension. Thanks in advance.

[Nick Arenas]

 

Does anyone know the exact location of this so called ac drain plug. I can't find it anywhere. A picture would be nice. Thank you 

[KARNUT]

20 minutes ago, Nick Arenas said:

 

Does anyone know the exact location of this so called ac drain plug. I can't find it anywhere. A picture would be nice. Thank you 

If it works turn it on and follow the drip.

[newdude]

25 minutes ago, Nick Arenas said:

 

Does anyone know the exact location of this so called ac drain plug. I can't find it anywhere. A picture would be nice. Thank you 

 

 

Read the whole thread.  There's a picture just a couple posts up.  

[KARNUT]

15 minutes ago, newdude said:

 

 

Read the whole thread.  There's a picture just a couple posts up.  

[broken1812]

Dealing with this right now.  Anyone able to get theirs unclogged and can offer any tips?

 

[Carl Rushing]

i have a 2013 Yukon, and the drain appears to be similar to what NEWDUDE shows in his June 12, 2023, post.

My vehicle is draining back into the passenger side (picture taken two weeks ago attached).  I looked again yesterday, and the black collar in the picture is gone. Over time, it must have become brittle and broken off.  I can feel moisture if I put my pinky in the drain hole location, where the water does not make it past the firewall.

Does anyone know the procedure to replace the drain?  As anyone knows, this is hard to access.  All the YouTube videos I found so far are worthless.  I need to figure out if there is some tubing left on the AC Condenser drain outlet and remove it. Trying to figure out how to install a new drain tube.  Plus Rock Auto is a little sketchy on the part and shows TWO different options.

[newdude]

37 minutes ago, Carl Rushing said:

i have a 2013 Yukon, and the drain appears to be similar to what NEWDUDE shows in his June 12, 2023, post.

My vehicle is draining back into the passenger side (picture taken two weeks ago attached).  I looked again yesterday, and the black collar in the picture is gone. Over time, it must have become brittle and broken off.  I can feel moisture if I put my pinky in the drain hole location, where the water does not make it past the firewall.

Does anyone know the procedure to replace the drain?  As anyone knows, this is hard to access.  All the YouTube videos I found so far are worthless.  I need to figure out if there is some tubing left on the AC Condenser drain outlet and remove it. Trying to figure out how to install a new drain tube.  Plus Rock Auto is a little sketchy on the part and shows TWO different options.

 

 

The drain on a 2013 is nothing like the drain on a 2021-up.  Totally different design. 

 

21-up has just that rubber grommet with that drain boot in the center.  

 

Your 2013 has a nipple that is part of the heater box that comes out of the firewall, and then the rubber 90 degree hose that slides on that nipple.  If the nipple is broken, you need a new heater box, or find a way to epoxy a new nipple onto it.  

 

 

Edited April 17, 2025 by newdude