2002 GMC Envoy AC heat haywire
About 25% of the time, the heat and
AC work fine. But most of the time, it’s
going crazy. The first indication will be
the display flashing and/or completely
cutting off. During the summer, I’d
have the AC on and all of a sudden it
would blow hot air, I can’t use the
controls and display flashing, until out
of nowhere, it settles down. Now with
cooler weather, it’s the opposite. With
the heat on, freezing cold air will start
blasting. Any ideas?
Sounds like you have automatic climate controls, meaning digital. I'd look to the blower motor control module first. Check the pigtails for any signs of getting hot or melting too. It's located behind the glovebox.