Bill Ball

Hot air right after starting with a hot engine is "normal" and none of the replacement valves will fix that. It is due to the fact that the system loses vacuum when shut down, allowing the valve to open. The design is failsafe to heat on. Somebody here modified the vacuum system to change this, but I don't have a link to that handy.

However, the valve should close quickly and once you get underway, the vents should quickly approach ambient if you have the temp slider all the way down without the AC on. If the center vent temp is above ambient, the valve is probably leaking. My vents ran about 10F above ambient just comparing one hand over the vent versus one hand out the window. There was not a noticeable interference with AC with this small leak. A new valve took care of this.

heinrich

Bill YES that one. And MYTHBUSTERS .. the vacuum in a perfect system is maintained and the heater valve wil NOT release hot waterinto your system.

Bill Ball

H'man: You've got a good point about maintaining vacuum. There is a check valve before the 4-way, one of whose arms feeds the climate control manifold. So, it should hold vacuum. Or is this wishful thinking?

oups59

I decided to order both the OEM



and This one? Part 74803



Will see if there is one better than the other. I will start with the second one since I have a good idea about the longevity of the OEM.

Bill Ball

Put in both in series.

docmirror

Bill, you are a warped, deeply bent and bizzare individual. And I love your solutions, we must have been separated at birth.

Erling G-P

Bill, thanks. Checked while driving today, and air from the center vent is def. warmer than ambient, even on the move, so I guess this indicates a leaking valve ? Somewhat puzzled by the way; if I selected 'recirc', still with AC off, air from the center vent got quite cool; cooler than ambient I'd say Is that how it's supposed to work ? (Btw. get virtually no air from the door vents when selecting 'recirc')

Cheers,
Erling

Alan

Recirc turns the AC on...

Alan

WallyP

If the rubber seal on top of the firewall behind the engine is missing or out of place, hot air will flow from the engine compartment into the air inlet...

Erling G-P

LOL, wonder if I'll ever get familiar with the intricacies of the 928 ventilation system...

Thanks Alan & Wally - 'wonderful' that there are always multiple possible causes for a problem...

IF it's the valve; is it relatively accessible, or do you have to take half the engine assembly apart to get to it ? (Alan, you mentioned something about replacing it with the airbox off)

Cheers,
Erling

Bill Ball

It's under the airbox. Not much to remove. You will lose maybe a gallon of coolant during the replacement process.

Erling G-P

Guys, I have a dilemma...

Would like to replace my heater control valve, as I suspect it isn't closing properly.

However, Porsche here in Denmark charge a rather outrageous $106 for this valve - at least when compared to the $16,95 at 928 International. Can of course order it from the latter, but their regular shipping is $40, and once I add customs, VAT etc, I end up with roughly the same price as here.

928 International kindly suggested an Audi part instead, but it's apparantly not available here. Dealer found a VW part instead that looked like OEM on the drawing, but it's rather expensive at $70 and would have to be ordered from Germany! (With no guaranty it actually fits...)

I may be able to arrange somewhat cheaper shipping from 928 Intl, but the report here that the OEMs are likely to fail after only a year, does not make it very attractive to use one of those at all.

Thus would like to try the Grand Caravan one that Heinrich mentions, but I can't order from Partsamerica (no international orders). Would anyone here be willing to order one from them and then send it on to me in Denmark ?
I will of course pay in advance, including a little compensation for the trouble - preferably via Paypal, as it's no doubt the cheapest way to transfer the money.

Cheers,
Erling

docmirror

I will gladly order and forward for you. Give me your address, and I'll go get two. I want to put one in my car as well. I'll either order from rockauto, or go get the metal one locally, whichever you prefer. The difference in price once I get it shipped is only a few dollars, er - Kroner - er, shekels. Oh what ever. What the heck, it's only $20, I'll pay for it, just send me your address.

heinrich

With pleasure.

Erling G-P

Thanks a bunch guys; very much appreciated

Docmirror, I'll shoot you a PM since you're the first who replied, but please let me pay for both valves - as thanks for your efforts

Cheers,
Erling