Started in summer. Very hot outside ac will only blow hot. Cool day no heat at all. Any ideas of what could be causing it. Does the opposite of what I need it to do
thanks

 

Sounds like you have a broken temperature blend door. Do a Google search for "2006 Equinox heater blend door" and you'll find plenty of info about it. In a nutshell, it's a weekend job to replace a $60 part (heater blend door actuator).

 

Thanks