2007 Chevy Tahoe AC Compressor Help

[Rambler Gambler]

Preface: I barely know what I'm doing. Through troubleshooting on my last Tahoe, I am somewhat familiar with the components of the air conditioning system and recently upgraded to a 2007 Chevy Tahoe. My father works on vehicles, but this problem has stumped him as well, any assistance would be greatly appreciated, and apologies for the ignorance in advance.

The Problem: I purchased the vehicle, a 2007 Chevy Tahoe LT 4WD 5.3l this past March, well before the weather really started to warm up. I checked the air conditioning when I took it for a test drive, but because I'm an aforementioned idiot, I took it for a short test drive and assumed the air was getting colder the longer I drove and didn't give it a second thought.

Now that the weather is warming up, I'm realizing something is wrong with the AC. The air seems to not get any cooler than the outside temperature, understandably cooler when the vehicle is moving. The heat seems to work just fine, and I can adjust it incrementally, which leads me to believe it isn't the blend door actuator (replaced one of those on my 2002 Tahoe).

What We've Tried:
1. Adding Freon (about two cans, ~1lb) - At first, the compressor was only at 10psi, but eventually started accepting freon. We used manifold gauges, and eventually (at the end of the second can) had the ac compressor fluctuating between 75 and 25 psi, at ~80 degrees outside temperature. Despite there being pressure, and some freon, there was no noticeable change in temperature. It's worth noting that the compressor was cycling, and didn't sound abnormal - tended to cycle every 20-30 seconds.

2. Did the 10a fuse "Reset": While I was pretty sure this was more for the blend door actuator, I tried this anyway. Removed the 10a fuse for 10 seconds (with blower completely off, vehicle off), started the engine, and waited a minute, then turned on the AC. No noticeable difference.


What we believe to be the problem:
Low-Pressure Switch (sensor?) - We tried "jumping" it with a paperclip, and after countless tries, weren't able to get any sort of spark/reaction. We didn't get in and check it with a voltage meter but plan to next time we work on it. What would cause us to not be able to jump the switch? We assumed, incorrectly, that the newer car might not allow it - but searching on this forum has shown otherwise. Could the problem be as simple as a new low-pressure switch?

Any recommendations would be sincerely appreciated. We plan to try more freon (since we only added 1lb, and chevy recommends 2.5), and potentially a new low-pressure switch. Is there anything else worth trying? If the compressor is cycling, it has freon, and the problem isn't the low-pressure switch, could it be possibly a leak within the compressor?

Thanks for any help, y'all are the best!

- A dumbass son

 

[kbuskill]

More info would help.

Auto or manual A/C controls?

When you say the pressure was fluctuating between 75-25 psi... was that high side pressure or low side pressure???

Low side at 80° ambient temperature should be 45-50 psi and high side should be 175-220 psi roughly.

It probably needs more juice.

 

[Rambler Gambler]

Thanks for the reply, @kbuskill!

We were reading that on the low side, moronically with the high gauge closed. We'll be taking these readings again soon and I will report back.

Manual A/C controls.

 

[Bill 1960]

Do consider that no Freon means a leak, unless someone has opened it up previously and let it out. When the refrigerant leaks out, often you’ll lose oil too.

Sometimes it’s worth paying a pro to get it right, you may avoid buying a compressor.

At the very least, finding and fixing the leak is job one. Soapy water is the old school method, but you cannot see inside some places. There’s dyes you can add that fluoresce. Pros will have an electronic leak sniffer. They’re not too expensive; I have one.

No need to feel stupid, none of us was born with knowledge; that results from asking questions and gaining experience. Stupid people are the ones who DON’T ask for help learning.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics, please.

As @Bill 1960 stated, the only stupid question is the one that is not asked. You are already receiving sage advice from the knowledgeable folks here on the Forum, and others will chime in.

 

[Rambler Gambler]

Rather than disappear into the abyss, thought I would pop back in and let you know what the solution ended up being.

When troubleshooting the system, we noticed that one side of the orifice tube was hot, the other was cold. We realized that this meant that there was a clog in the tube and it needed to be replaced. Less than $20 from your local parts store, just make sure you have a means to responsibly vacuum and dispose of the freon in the system. Otherwise, a fairly easy and straightforward install. Hope this helps someone else in the future! Check your orifice tube.

 

[swathdiver]

Rather than disappear into the abyss, thought I would pop back in and let you know what the solution ended up being.

When troubleshooting the system, we noticed that one side of the orifice tube was hot, the other was cold. We realized that this meant that there was a clog in the tube and it needed to be replaced. Less than $20 from your local parts store, just make sure you have a means to responsibly vacuum and dispose of the freon in the system. Otherwise, a fairly easy and straightforward install. Hope this helps someone else in the future! Check your orifice tube.

So what was yours clogged with? After 11 years, mine is still spotless.