Front A/C not cold, the rear works fine?

Tiny
JHALL41422
  • MEMBER
  • 2015 CHEVROLET SUBURBAN
  • 17,000 MILES
Front A/C not cold. Back works fine. Modes works we can switch to defrost etc, but the air is just room temperature. Freon levels are fine. The condenser was replaced due to a deer incident 6 months ago. Have checked drivers and passenger actuator and they are fine. What would be our next item to check? Please help
Sunday, August 13th, 2023 AT 11:07 AM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
This is the third time we have had this problem on the site, can you please let me know what happens? I believe there is an air dust outlet temperature sensor that is bad or the ambient air temperature sensor is not plugged in or is bad, we should do a CAN scan which will go through the system and report back with any shorted or out of range sensors, you can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here are the locations of the duct and ambient temperature sensor so you can check it out. Check out the images (below). Please let us know how it goes.

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Monday, August 14th, 2023 AT 4:29 PM
Tiny
JHALL41422
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  • 4 POSTS
We have an OBDII +CAN scanner. And it is not showing any codes. How do we figure out which sensor may not be working?
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Thursday, August 17th, 2023 AT 8:21 PM
Tiny
KEN L
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  • 54,144 POSTS
Does the scanner have the capability to see the sensor values? It may not have a code if the sensor reading is off, in other words one of the sensors can be reporting back to the HVAC module that the inside cabin temperature is -20 degrees in which case the AC will not work. Also, we might wat to try to reset the system, you can try disconnecting the battery overnight to see what happens. Also it could be a software update that is needed.
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Friday, August 18th, 2023 AT 10:14 AM
Tiny
JHALL41422
  • MEMBER
  • 4 POSTS
We left the battery disconnected overnight a few days ago. No change. The scanner doesn’t show any HVAC sensors. But could it be a sensor if the rear A/C is working? If yes. Which sensor controls the front A/C? We may just go ahead and replace it to see.
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Friday, August 18th, 2023 AT 10:33 AM
Tiny
KEN L
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Okay, there are four sensors though as described above. This is a new problem for GM, so I am very interested to see what the problem is. It could be the HVAC controller, can I ask which CAN scanner you are using?
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Saturday, August 19th, 2023 AT 9:26 AM
Tiny
JHALL41422
  • MEMBER
  • 4 POSTS
Hey! Update. After scanning with snap on scanner. Still no codes. Finally figured out it was the evaporation valve. $25 part and it works great now!
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Saturday, September 2nd, 2023 AT 3:16 PM
Tiny
KEN L
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Thank you so much for getting back to me :) so for clarification this is the valve you replaced? Check out the images. (Below)
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Sunday, September 3rd, 2023 AT 10:29 AM

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