2014 Silverado A/C blows warm air, two mechanics that checked it are stumped

[D_wayne09]

I bought this truck in 2019. When I first got it a/c worked great but every once in awhile it's blow warm air for a short period of time before going back to cold again, usually after turning off truck then starting again. 

 

Past couple years during the summer it's starts blowing warm no matter what. 

Last summer I disconnected my battery for another issue & upon hooking it back up the a/c started working again and stayed that way until this summer. 

 

I've had two different mechanics look at it and they have no idea what's going on. 

 

- a/c clutch is engaging

- low side lines are ice cold under hood

- condensation dripping from port on firewall

-had thermal expansion valve replaced twice along with all the seals.

- had system vacuumed, recharged and tested for any leaks twice. 

- fans are working

- fuses good

- changed cabin air filter

- inspected blend door actuator and it's turning as I turn the dial from hot to cold as it should 

 

Despite all that it still blows warm. Sometimes after sitting all day it'll blow somewhat cool before slowly getting warmer and warmer.

 

Anyone have any idea what could be going on? These Florida summers are brutal with no a/c. 

[Jsdirt]

You've clearly got an electrical issue. You need to find another shop that's well versed in electrical troubleshooting. These days that is a MUST. Not everyone has the skills (Or the patience / motivation) necessary to find electrical gremlins in modern vehicles. The newer the vehicle, the more difficult troubleshooting becomes.

 

That said, STAY AWAY from ANY dealer. Find a local, non-dealer shop that has good reviews online, and that the locals speak highly of with electrical issues. This one seems to be intermittent, and is going to take some skill to nail down. 

Edited August 5, 2023 by Jsdirt

[Duelin]

I would be looking at the blend doors. And If you have a bi-directional scanner you can reset the positions of the blend doors to their home position. Its not uncommon for them to get out of calibration.

 

Also what can happen is the heater blend door has a piece of foam that helps seal the door when closed. And every once in a while that foam will come loose and fall down and jam up between the door. And then instead of sealing the door shut it jams the door open and won't let close all the way. Now you will get constant heat moving thru there.

 

Good Luck

[Jsdirt]

Yep, another common failure point. So many it's hard to keep track these days!