Porschefool

I seem to be having the reverse of the common problem around here, and just want hot air in my chilly '84; my HVAC head sliders seem to be dead, though the blower speed switch works fine. It's my understanding that the heater control valve defaults in the open position, allowing hot coolant into the heater core. The air coming from the blower is lukewarm at best, even with the engine at operating temp. Any tips? Even if I have a massive vacuum leak somewhere, I should still be getting hot air, shouldn't I?

The Forgotten On

You could try disconnecting the valve and plugging its vacuum line. BTW, what year is your 928? The HVAC systems are 78-79 manual climate, 80-82 manual climate, 81-83 auto climate, and basically stayed the same to the end of production after that.

The manual systems have the vacuum solenoids in the head itself while the auto units have them mounted under the HVAC box.

It would help determine what is the best fix for you if you could give us the year. Good luck on the fix

Porschefool

Thanks for the reply. As I mentioned, it's my "chilly '84"
Appreciate everyone's input.

The Forgotten On

Sorry, missed that. You should check the flap adjusting motor that is on the drivers side. Sometimes they need new transistors soldered in place as the old ones burn out. The thread it is on escapes me for the moment.

Also, it wouldn't hurt to crack it open and clean the metal tracks that the slider rides on. They can sometimes get corroded and not detect a change in slider position.

j.kenzie@sbcglobal.net

Also, check your coolant level, especially after a coolant change.
Good luck,
Dave

Porschefool

Thanks for the pointers, fellas. The car has been sitting due to the heating issue for about a week now, and as I was preparing to follow up on your ideas I discover that my brand-new monstrous Group 49 battery is completely dead. To quote the great Gilda Radner, "it's always something..."
Ah, the joys of Shark ownership.

Alan

Well you may need to replace the heater valve - about the only thing that would stop flow would be a faulty valve that is stuck closed. Nothing much else needs to work for a hot heater core.

But you will need to make sure the heater flaps are open to get good circulation - you can fix them there to get heat even if the head unit isn't controlling this correctly.

Alan

Porschefool

I'm all over it, as soon as I'm done searching for "parasitic draw" on the board...