Chevy A/C High Pressure Connector

I have a set of R134A gages and the high pressure coupler connector won't lock onto the high pressure port on my 2004 Avalanche? I've used this gage on several cars with no problems. I even tested it on my Dodge with no problems. I even had an old schrader valve laying around and it locks onto to it with no problem. Is there something different about Chevy's high pressure A/C connection?

Inspect the port and make sure it isn't damaged..

If your system doesn't have any "freon" left in it you could change it out. The whole unit swaps out. I just did  that in my truck because it was leaking.

Rodney

My low pressure port checks out at a perfect 45psi so I'm reluctant to change the high pressure port. I have a new high pressure quick connect I bought at NAPA and I'm waiting for the adapter to connect to my gages to get here. Hopefully I can get a high pressure reading soon. I hate to change the entire Schrader valve for this!

Is your compressor cycling fast? If so then you might have an issue otherwise I wouldn't worry about it then if you are getting cold air.

You can't change the high pressure port on your truck if it is one piece like mine. It is not an actual shraeder valve but a little different setup and it can't be rebuilt. To replace it you end up venting the system.