We have a 2012 Chevrolet Equinox. We cant turn off the interior heat even when we turn the temp all the way down. Even when we turn off the heater it keeps blowing hot air.
What could be the problem?
This feels like a broken blend door. A blend door controls how much air is allowed to flow past the heater core, or past the a/c evaporator. A broken door means that air physically stuck going past the heater core, thereby heating it up.
Unfortunately, those doors live inside of the heater box, which usually requires you to rip apart the dash (and then remove the box and take it apart), which requires discharging and then disconnecting the A/C lines. Quite a project.
This sounds like a stuck or faulty heater circuit valve. There's a pipeline from the engine coolant system that goes up to a heat exchanger in the air conditioning duct. There's a valve that regulates how much hot coolant flows in this circuit, and if that valve sticks open or its actuating linkage is broken, the system will be on hot, hot or hot - No matter what you do with the controls.