[schembfr]

Thanks Wizzer and everyone! Same problem 2004 Highlander. Started with a/c intermittently shutting off while driving and it would work again when I jiggled or moved temp control knob. Got worse and worse until pretty much just steaming hot air blowing at me while a/c on. Tonight, spent 5 minutes- pulled off temp control knob (middle one -just pulls off), and found loose nut on switch. Tightened with 7/16" deep socket wrench and a/c worked perfectly again! I probably do have a loose wire behind there, but at least I know the problem and can take it apart when it stops working again.

I was quoted $800 for this repair by Toyota of Weymouth/ Braintree MA for an entire new heater control unit. At this point, it looks like I would've paid $800 to basically tighten a screw. It would've been me who would've gotten the screw!