Heater runs when A/C on
 

I have a 1982 924 I just got. The heat runs when the A/C is on, making the a/c less effective. It either blows out at the feet when the middle knob is to the left, up thru the defrost when slid over to the right. A/C blows cool air fine and a new compressor was put in. I read in another thread that it may be a heater flap control. Any advice appreciated...the dealer is a little stymied by it all.

Hmmm I have the same problem and from what I have heard it might be the heater control valve (HVC, about $20-$30 with shipping on pelican) if so this site should help a bit. Its for the early 944 and 924.

944 Foot To The Floor: How to repair heater control valve on a Porsche 944 (Square Dash Model)

Thanks!!...will give it a try and respond when done.

Turns out that the inner steel portion of the heater control cable was broken at the heater control valve, and the valve was in the wide open position, thus making it blow hot air all the time. Replaced the cable and now works like a charm. Why the dealer could not figure this out is beyond me!!