Ac not as cold
 

I have a 2008 hhr with almost 200 000 miles on it, the ac was blowing cold now it started to blow a lot less cold after I got gas and turned it on, I know that the thermostats bad I just haven't replaced it yet, I know sometimes that shuts down the ac but when that happens the temperature guage doesn't work, the temperature guage still works but not the ac, I'm pretty sure I can hear the compressor kick on

Replace the thermostat AC Delco 131-158 180 degree , only! and the Dexcool only lasts 5 years so drain and fill with 50/50 mix

Need more information and clarity;
I got gas ?= put freon into system or gasoline in tank?
Do you have an engine running hot trouble?
A cooling system flush and thermostat service will help that.
Seems you are combining the A/C not working symptom with engine cooling.
Priority would be the engine correctly at the optimal operating temperature.

i got gasoline i don't think that has anything to do with it it but it was working fine before then and then I turned it on, and it was a lot warmer

the engine is not running hot but I know the thermostat is stuck open because I have that code

Don't look at the gauge, look at the digital temp. If you have as P0128 the AC is disabled.

X2 ^^^^^^^, that code? Is it P0128? Change out the thermostat!

....................X3 change the 'stat & service the cooling system too if possible (flush and refill w new antifreeze-H2O mix)

clear the code(s) and let's see where it's at after that!

Not just coolant….Dexcool and potable water 50/50 mix!

A stuck open t-stat does not cause overheating it causes underheating.