FRUNKenstein

Ok, 928 newbie. Just picked up the car yesterday. Driving from Indianapolis to KC today. Yesterday the car drove well, but blasted us out with heat. No problem, I'll just zip tie the heater control valve shut. I researched last night here and then go out to the hotel parking lot to do the deed. After removing the air box below is what I found. Obviously there was recent work done with the shiny new brass valve. But I don't see anything that looks like the heater control valve I see in the photos in the writeups here. Nothing down there has a control arm to tie off. Is the new part a new type of heater control valve?

928 at last

Someone's replaced the OE valve (Plastic) with the one you've got in there.
Thus, ...No external arm.

Bertrand Daoust

It should be where the brass valve is.

First time I see this kind of valve.
The stock part is made of black and white plastic.

http://shop.site-link.com/928intl/pr...928-574-573-04

jcorenman

The brass-colored thing is the heater valve, an aftermarket replacement off some other car. It should work (if it is the correct type), but as noted has no external actuator arm, nor any (external) way to tell if it is open or closed.

The first thing to check is that the vacuum line is properly connected, it is the white-ish nylon tube in your picture (below). The (stock) valve is normally open, it will be on full-heat with no vacuum (i.e. leaking or disconnected vac line).

There is also some serious funkiness going on with that hose clamp-- looks like a hack because the short hose is the wrong size (too large).

Which of course raises the question of whether the PO installed the correct type of heater valve. Generic valves come as either normally-open or normally closed types, if the vac line is OK then my guess is that a normally-closed valve was installed, and vacuum is opening it instead of closing it. If this is the case then disconnecting the vacuum line would shut it off and solve the immediate problem.

And if it turns out to be the wrong type of valve (and given the hose-clamp funkiness) then the next concern is whatever else the PO might have touched. Do you have receipts, so you know where to look?

The part# for the stock heater valve is 928-574-573-03 (MSRP $96.22 but available for e.g. $25 from 928 Int'l as Bertrand noted), the short hose is 928-574-567-03 and the clamps are 999-512-346-00. For the stock valve, be sure it is oriented correctly as noted above-- black side towards the engine.

P.S. While you are in there, check the U-shaped fuel hose that lives just under the MAF, between the fuel regulator and damper. For now make sure it is smooth and not cracked, but plan on replacing fuel hoses soon. Depending on who was in there last, the MAF may just pull out of the rubber boot at the bottom, or you may need to loosen the hose clamp that secures it-- a long 1/4" extension and a 7mm socket, and go in just above the right-side fuel rail (car's right side, US passenger's side)-- assuming it is not oriented in some funny direction.

syoo8

Hi KCattorney,

If you'd like help sorting through your HVAC issues- I'm no Jim Corenman (by any means) but I've done it twice now. I'm in the middle of Missouri.

FRUNKenstein

Thanks for all of the help. It's very much appreciated! Yep, looks like I've got some sorting out to do. You guys here on the 928 board have some serious gurus!
So far today we're just getting ambient air - not heat. Keeping my fingers crossed it holds out for the next several hours.
Scott, we will be at Shakespeare's Pizza downtown CoMo at 3:00 pm today stopping for lunch with my Mizzou freshman son. If you're in the area, stop by.

syoo8

KC- PM sent.

Imo000

That's a Chrysler mini van heater valve. Common replacement for the plastic one. It's supposte to be leak proof because it's metal. Check the vacumme line.

FRUNKenstein

Thanks Imo. Good to see a familiar face over here on the 928 board. Like others have done, I was thinking about putting a shut off valve in the line. I assume that goes in after the heater control valve before the firewall? Obviously no room in the short hose between the block and the heater control valve. Any suggestions for the part to use for that shutoff valve?

docmirror

You can put a manual valve in there, although it's a tight fit. You would put it before the firewall, doesn't matter on which side of the heater valve it goes on.

For now, run the car, put the HVAC on the cold setting, and remove that white vac line. Test that you have good vac on that line with your finger. If you don't the vac solenoid control is in bad shape. If you do have vac on that white line, connect it to the heater valve and that should keep the hot water out of the heat exchanger inside, and keep it fairly cool.

If you do NOT have vac on that white line, your next best bet is to take the pressure off the cooling system, take off that funky hose clamp, remove the regular hose clamp that holds the hose to the heater valve and put a marble in that line to block it until you get home to fix it right.