There is no voltage going to the heater control valve.

Had this happen this weekend, thanks for the link. Even on a warm muggy South East evening, we were getting FROZEN out of the car. Had to basically keep the fan running, and cycle the A/C on for maybe 30 seconds to a minute then off once we were *cold* again. Had the system turned up to 90 degrees. I opened up the valve manually and will just leave it there. The A/C system should be able to easily overcome any heat coming in. I've never had a car with a valve like this. On my Miata, Protege, Jetta and S2000 and I *believe* 03 Pathfinder I've had over the years, water always flows through the heater core. Now with the valve manually 100% open, the A/C's been blowing at the desired temperature. Easy / cheap fix. I think if it ever breaks I'm just going to put a pipe fitting between the 2 hoses... what a silly part to have, made of plastic.