Hello all,

I have a 1993 945T. Just replaced the heater control valve with a Volvo part - the cheap (FCP groton) aftermarket one leaked after just one year. I have learned to buy Volvo parts the hard way... But that is another story.

My problem is that the heater control valve doesn't close. It seems as though the vacuum is too weak to close the valve. (I can feel some vacuum in the line to the valve.) The vacuum coming from the engine seems okay. The other HVAC controls seemingly work fine: I can select floor vents, blowing at me, or dash vents and think that the recirculation vent works also. I don't hear anything when the heater knob is turned from the cold (off) position to a warmer position. I think that I remember that there used to be a brief "hiss" when I turned it. My recollection is that the heater control valve worked okay last summer. Any suggestions as to what to check first?

Thanks,
Steve