2001 pontiac sunfire problems

I have a 2001 sunfire. recently when you push the rear defrost button the service and theft lights come on. was told to replace heating/ac unit. did it today but lights came back on. please help.

this is electrical in nature. you are getting a short. not really understanding why you would replace your heater or ac. go to the dealer and have them look at this as they are really better prepared at gremlins related to electronics. otherwise, you could just live with it and consider it a false alert.

I’d suggest taking it to a shop that specializes in automotive electrical systems.
Without a schematic, I can only suggest that the systems interact somewhere, perhaps in the Body Control Module (BCM). A shop such as the one I suggested will have the schematics and expertise to do a proper diagnosis.

It is a 13 year old Sunfire. Just stop pressing the rear defrost button.