A/C evaporator freezing up

INDY1K

MEMBER
2007 CHEVROLET TAHOE
5.3L
V8
4WD
AUTOMATIC
203,657 MILES

On my vehicle listed above, after 15 minutes or so, it appears the A/C evaporator is freezing up. The compressor is not cycling off and on. It does shut if if you it off. Also, lots of water leaking from the Evap box under the car. Someone said it is the Evaporator Temperature Sensor, but I cannot find reference to it for a 2007 anywhere. Is there one on the vehicle listed above? Where is it and can it be changed?
Thank you for your time and help.
Kevin

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

It could be the sensor but we need to start with the basics first or you could be wasting your time with a sensor issue. The reason is, the A/C is cycled on and off based on pressure and not the temp sensors in the HVAC housing. Those sensors are monitoring the air temp that is blowing in the cabin and it will adjust the blend door if needed but will not cause the compressor to continue to run or not run.

This is why we need to monitor the A/C pressure with it on and see what it is and that will tell us what is happening.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

As for the water coming out, that is due to the evaporator freezing and then thawing.

Let's start with this and go from there. Thanks

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Sunday, January 3rd, 2021 AT 6:28 PM

INDY1K

MEMBER
2 POSTS

So, are we saying there is no evaporator temperature sensor on the 2007 Tahoe?
I know the low pressure sensor is working because the compressor was not running. I put dye in and recharged the system The compressor came on and I was able to detect a leak at the evaporator block connection for the rear A/C system. I need to fix this first and report back. I would like to change the orifice tubes at the same time and continue. I will get an A/C vacuum system to do this and report back. Thanks

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Sunday, January 3rd, 2021 AT 7:22 PM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. That sounds like a great plan. Clearly any leak needs to be repaired before any other diagnosis on this system can take place because it is a sealed system. So if it is not actually sealed then we have to fix that first.

Let us know how it works out after that. Thanks for the update.

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Monday, January 4th, 2021 AT 6:42 PM