newworld

87s4aut. I did a full refresh AC...new hoses. Etc I also added an extension to low side port. Pressure tested and held vacuum. Ran engine AC compressor clicks on and sucked in r134a.

Went inside car and got warm air thru vents. Gave up an called it a day.

Next am, turned on AC and it was cold good AC. Then after car warmed up no AC.

I know something is amiss with heater valve as heat comes on and probably overpowers AC.

My issue is that besides just swapping out a new heater valve, I don't know what to troubleshoot.

Any help appreciated. There is a vacuum connection to heater valve. I think my issue somehow is when AC is turned on I do not know how that heater valve is actuated.

The previous owner did all kinds of things with car so there my be vacuum lines not working to that heater valve. I was wondering if there is a way to turn on heater valve for winter and shut it off for summer.

I think heater valve is fine, I do not think vacuum or triggers when AC is depressed is connected or on. AC compressor does engage clutch and all is well with AC system itself as u do get cold AC on cold engine.

SeanR

Go to www.928gt.com and go to 928Tips and follow Wally's World. He's got the perfect write up to diagnosing this.

newworld

Read that write up. Very nice one.

My only questions additions for Wally is on the vacuum part. Does the vacuum do what for the center console flaps etc? I understand vacuum white line is from heater valve and somehow triggers a close on heater valve. So I guess a bondage bypass during summer would be to connect vacuum line from brake booster to heater valve so heater valve is always closed in summer.

I don't understand the other multi color vacuum lines....do they keep flaps open?