2016 Suburban Rear AC blowing Warm

[usaf27]

Howdy all. I’ve got a 2016 Suburban. Last year I replaced the AC Condenser and Compressor due to my entire AC system not blowing cold air. I recharged it all properly and AC was working great. Now just the rear vents will not blow cold air.

Where should I look for this issue? Just wanted to see what is common before starting to tear into it.

Thanks!

 

[Matthew Jeschke]

Sounds like maybe a TXV valve issue. If you replaced the rear evap, did you put back the bulb sensor / install the bulb sensor? It's connected to the TXV valve.

First check.... Remove the rear cover and check the inlet and outlet on the evap. Once side will be ice beer can cold. The other side a bit less cool. This is the boiling / superheat process. If it's not taking place then there's no pressure differential to create the boiling / cooling effect. I always check this before I ever hook up any gauges. It's simple and quick. You can even charge with this measurement if you have the right tools.

Sub cooling is the condenser similar check but will be HOT w/ temp difference between inlet and outlet.

Did you flush your system before you bolted on the new parts? Years ago I rebuilt mine only to get debris in the rear evap. I tore it down and while I was in there replaced the TXV valve.

Note the Blub sensor is a part of the TXV valve. It meters / regulates refrigerant flow.

 

[usaf27]

Sounds like maybe a TXV valve issue. If you replaced the rear evap, did you put back the bulb sensor / install the bulb sensor? It's connected to the TXV valve.

First check.... Remove the rear cover and check the inlet and outlet on the evap. Once side will be ice beer can cold. The other side a bit less cool. This is the boiling / superheat process. If it's not taking place then there's no pressure differential to create the boiling / cooling effect. I always check this before I ever hook up any gauges. It's simple and quick. You can even charge with this measurement if you have the right tools.

Sub cooling is the condenser similar check but will be HOT w/ temp difference between inlet and outlet.

Did you flush your system before you bolted on the new parts? Years ago I rebuilt mine only to get debris in the rear evap. I tore it down and while I was in there replaced the TXV valve.

Note the Blub sensor is a part of the TXV valve. It meters / regulates refrigerant flow.

I never messed with any of the rear AC components. I only replaced the front Condenser and Compressor as I saw leaks (dye) coming from both. After that I vacuumed the system in which it had held a successful vacuum.

I’ll take a look at the rear AC evap and check that out first. Thank you for the sense of direction!

 

[Matthew Jeschke]

I don't know if this will work... but you maybe able to go near rear bumper where the high and low pressure lines go to the evap and do a superheating test there. The touch test I recommended. Mine are exposed just inside the fender behind the tire (below where evap is in rear air system).