estomax

iTrader: (2)

you can test the heater control valve by pulling the vacuum hose out of the plunger and seeing if it opens (hot water going through heatercore) and then putting vac to it which closes it (hot water not going through heatercore).

a simple diagnostic step anyway...

Marko

Aron9000

Its not the heater control valve. I had somebody sit in the car and turn the **** from max cool to max hot, back and forth. The little servo motor works fine.

I'm having the a/c on the house serviced next week, preventative maintenance. The guy said he'd hook up his gauges to my car and let me know if I'm low on freon, and hopefully give me some advice on what to do.

estomax

iTrader: (2)

You are talking about the mixer flap in the dash? The heater control valve is a vacuum solenoid in the engine bay on the pass side near the firewall that controls hot coolant going into heater core.