2016 Tahoe A/C issue

[Twnotter]

Cruising down the highway and the A/C started blowing some warm air. Figured it was just a freon leak, since there are known issues. Grabbed some gauges and then I got lost real quick.

When the car sits, it will start and the A/C gets cool. Outside temp is around 80. It stays cool for a couple of minutes and then slowly turns back to outside air temp. I tried adjusting the temp to see if there was any change where he could just be a stuck gate. No difference. I thought the rear air seemed a little cooler, but I could not duplicate it enough to say there was a big difference.

I went and checked the low side piping. It would cool at the beginning and return to an outside air temp. I only did it by touch and did not use a temp gauge.

Checked the compressor and the clutch was engaging like it should.

The gauges is what got me. Low side is 60 psi. It would fluctuate between 60-65. So, it is higher than it should be. Once switched on, the high side would start at 225 or so and then gradually decrease to 150 on one test to 175 on the next.

Turned the system off and let it sit. It took over an hour for them to settle at similar pressures. High side was still above by 15 psi.

So, I am lost now. I cannot find what would cause a high low pressure side like this. I have read so much and watched too many videos. Some claim the TXV is only for the front and could be an issue and the rear only uses an orifice. This doesn't sound right but I want to get some opinions before I start taking this entire thing apart and replacing parts I don't need to.

 

[Big Mama]

Welcome to the forum from Virginia. There are lots of knowledgeable folks here to help. It may be different on your rig but on my Sierra the problem was the condenser but I didn’t put gauges on it before taking it in.

 

[Miami-Dade]

@Twnotter In my case it was the Condenser just like @Big Mama. Mine went belly up at 80K miles. It was a known issue on just about all 2015-2017 models. If you have the original Condenser that just might be the issue. It was under a warranty so dealer fixed it.

Welcome from Miami&NYC!

 

[Matthew Jeschke]

I don't like to hook up gauges if I don't have to. This is something the FSM won't explain but is VERY helpful. I like to check super heating and sub cooling first. You can get a quick IDEA of what maybe issue. A good AC tech will start by checking temps. It's a lot quicker and more effective in my opinion. I have no clue why FSM doesn't explain that process.

Put hand on two lines going into evap (do this on both front and rear). Is one side is icey beer can cold (input after metering device / orifice tube or txv) and other side bit warmer (output). Next check the condenser. One side should be really hot and other side bit cooler. You may need a temperature gun to do the condenser. You can also run temperature gun across condenser to see if there's any dead spots in it / dramatic temperature jumps.

There are charts and tables for the sub heating and supercooling temps you should see but a sanity check should give you an idea of where fault may lie. You have to google them for the given refrigerant. I think approximately 10f delta on evap is roughly good enough but I just do hand check. It's hard to get good reading without AC tech tools. I don't recall at all what delta is on condenser... so long as it's cooler on output should be good sanity check... like considerably cooler... 50f? Other people who are more knowledgeable can chip in here..

If the TXV's bulb sensor (rear) isn't functioning the AC will have intermittent / poor performance. That maybe your issue. The rear air simply taking all the refrigerant flow.

Once you are comfortable with theory of operation for refrigerant cycles you'll bang your head and wonder why you ever paid thousands for other people to work on the stuff. It's really simple.

NOTE: I have a 2001 Tahoe and front air uses orifice tube, rear uses a TXV w/ bulb sensor.

 

[2020RangerEd]

I've had to replace the rear seal (back seat), the front seals and the latest issue was a condenser seal on my 2016 SLE in the last three years. Garbage components in my opinion. GM dropped the ball on this system. Garbage in, Garbage out. I'm hoping that's it for this vehicle HVAC. It's cost me a fortune. My neighbor has a 2016 Silverado and his condenser is also leaking. Just an FYI for other owners.

 

[arkie]

GM extended the warranty on the 16 Yukon condenser to 5 yrs from delivery.
All were subject to a crack
Mine went out about 2 months after warranty expired

 

[RST Dana]

GM extended the warranty on the 16 Yukon condenser to 5 yrs from delivery.
All were subject to a crack
Mine went out about 2 months after warranty expired

Mine went out 5k miles after warranty as well. They split the bill 50/50 with me.

 

[Big Mama]

It’s a shame. GM really dropped the ball on this one. The lifter/cam issue, the trans issue, and the AC condenser issue are terrible. GM not stepping up is worse.

 

[travisk]

Had issues with mine last year. One similar issue you described as cooling at idle then all of a sudden temperatures rising. I figured out it was my cooling fans that where shutting off for whatever reason....Thinking it's a ai logic issue (guessing the engine temperature is cool enough for it to think it can shut the fan off but it's like it forgot that the AC is also on and needs air flow across the AC condenser while sitting at idle to be able to cool)...

Also mine didn't cool that well at idle when it's 100+ degrees out... Had bought a Diablo tuner to be able to increase idle speed to 900 RPM when in park... Also now with the higher idle the cooling fans are forced to stay on to keep the engine cool which also keeps air flowing across the ac condenser. Not ideal but it's the only thing I've figured out to be able to remote start my truck and have it cooling for a little while before I get in it on 100+ degree days.

My AC can work great because I've seen it do it for short bursts but the AI logic adjusts the AC compressor so much im guessing to keep it from freezing up the evaporator and fluctuates my vent temperatures too much...