Originally Posted by CobraMike

I have the same problem. Dealer said it was not covered under Warranty. The Heater control valves are normally open. The Heater Control Module grounds the valve which causes it to close. There are 3 wires on the valve, the center one is 12v and the 2 outer ones are the control signal. In my case the Control Module is bad and the passenger side never turns off. The Heater Control Module is part of the Dash Board Controls and there is a good test procedure in the Service Manual. To test mine I put a jumper wire on the center pin of the Heater valve to the positive post of the battery, put jumper wires on the outside pins on the Heater valve and ground them. You should be able to feel the valves close. Start the engine and turn on the AC to see if it is cooling now. If you remove one of the grounded jumpers that side of the car should get warm quickly.
To double check the module itself. Measure voltage from center pin (2) of the cable to ground. It should be 12Vdc. Measure from pin 1 to 2, then 2 to 3, with the heater set to cold (Blue Dots) and you should read 10 to 14 Vdc. If you do not see 10Vdc or more then the module is probably bad. If you press the R.E.S.T button with the car off you should hear the pump under the rt headlight turn on with the temp controls set to heat (red Dots).

Good Luck,
Mike