when i am sitting idle in park w/ my AC on, as soon as i press the OFF button on my AC, the engine turns off with it. this doesnt affect me while i am driving, but i tested it out while i was reversing and i can tell the engine was about to shut off when i pressed it.

it's not a big problem for me right now, but i dont want it to escalate into something huge. does anybody know why this is happening?

 

It could be an idle air control valve (IACV) issue. When AC is on, the IACV is opening more frequently to hold slightly higher engine power and maintain idle RPM. When AC goes off the IACV, would close more frequently to reduce air flow and maintain idle speed (no increase in idle speed). Your IACV may be sticking open, or may completely close long and choke-kill the engine.

Clean and check IACV for function.

good luck