Question about AC
 

Hi all, I have a 2008 hhr about 280k miles on it. Never once had a problem with this guy except I had to replace the battery some years ago. About 3 months ago the AC seems to have stopped working. Air will still blow out at full strength but it is not cooled at all its just blowing ambient temperature air at me. I am not much of a car guy but have an engineering background so not afraid to DIY. I am just a little unsure of what could be the cause of the issue, from searching it looks like I made need to replace the refrigerant or could be a full on compressor issue. Was wondering if anyone else has encountered this problem and if there are any quick ways to tell whether I need to look at replacing the compressor or just buying some 134a, thank you!

Are you ignoring a CheckEngineLight?
What is the digital coolant temp?

If the thermostat is not working correctly, you will get a CEL, the temp readout will show --- and the A/C will stop working.

No check engine light, coolant hovers between 187 - 192 while driving, most of the time its at 190 degrees

Use your Mark I optical sensors yo see if the compressor clutch is engaging. Then check the diode #9 and fuse #22 in the under hood fuse box. Then look at the connections on the AC switch.
I don't recommend those freon kits, unless you know what you are doing. The freon does not leak unless the connections have been messed with.
I know it is technically not freon.