I have Gmc Sierra 2005 and I disconnected battery and now the a/c is blowing hot. It stars out cool but goes hot. Today when I started it the driver's side is cool but passenger side is hot now. This is crazy!!! Help me if you can Thanks Rusty

Is the compressor running when it blows hot air ?

you have taken the calibration out of sink. you will now have to remove battery power again for about 5 minutes. after this time reconnect the battery. then turn key to on position for 3 minutes but do not touch the heater control or temperature controls. This should allow the heater and ac system to recalibrate. once the 3 minutes is up turn key off and then back on and start truck.. Try your controls again and see what happens. if no change then dealer will have to reprogram the heater control calibration for you.

Give some more details of the problem.

If air is hot then cold it sounds like you have a sizable air pocket in the cooling system. This could be caused by a leak or if you have recently done anything to the system without bleeding it afterward.

stuck thermostat, replace stat

you have a couple of problems first of all your drivers sd=ide heated heat pad is probably faulty, for your heating problem you may have to get the hvac doors recalibrated.

need to go to dealer to have HVAC module reprogramed. whenever diconnecting battery power on these vehicles you can connect a 9 volt battery between neg and pos to keep the memory in the computers. I am an master ase technician and 5 classes from gm world class tech.

THERMOSTAT REPLACE IF NOT SEE IF HOSES ARE CLOGGED SHOT OF AIR COULD HELP OR DISSCONNECT BATTERY CABLE 10-15 MIN CONNECT BACK TRY HEATER

you need to have the actuators reset you can try unhooking battery again if not it will have to be done by the dealer

had the same problem/. it's the ac plenium