MahoreLee

I have a 1986 Porsche 928s auto that only does full heat. I've looked up under the drivers side about 5 times now trying to find a white clip or where it should be and can not find it. I know it is knee hight by the gas peddal. Does anyone have any pictures or a better description? Perhaps there's a cover I need to remove?

I have this picture : http://www.clarks-garage.com/shop-manual/hvac-01.htm but can not find anything that looks even close to that.

Adamant1971

Start by replacing the heater control valve, then by testing the vac lines one by one to find out if any of the diaphragms are busted.

To get at the lines you need to remove the carpet side cover that runs along the left side of the console.

http://dwaynesgarage.norcal928.org/1...0Procedure.htm

Mark Anderson

this should help
http://members.rennlist.com/pirtle/svc_act.html

MahoreLee

Thanks, those links are helpful. But I really want to figure out where that white clip is first just to make sure that the issue isn't as simple as it being broken.

Adamant1971

Have you checked the heater control valve yet? That is the most common source of always heat, the next being the diaphragm for the top mixing door or a combination of both.

All of my 928's have exhibited always heat, and every time it has been the heater valve. When you turn to heat it opens coolant flow to the heater core, when it fails hot coolant is always running to the core.

SeanR

What white clip? It's not a 944.

The Forgotten On

Get out a hand held vacuum pump and start testing everything looking for vacuum leaks.

I had a failed solenoid giving me issues before I located it. And before that it was a few of the diaphragms in the HVAC box including the dreaded recirc box above the fuse board.

Just take your time and check everything.

ROG100

I want to know as well - what white clip???

MahoreLee

I could have sworn I saw the white clip referenced on 928s. Would make sense why I couldn't find it.

I went to Napa and auto zone. Napa wanted $200+ and autozone said $150 for a vacuum pump. Just ordered one on Amazon for $20.

MainePorsche

Do not go to Napa for 928 material.

j.kenzie@sbcglobal.net

I think you want a hand vacuum pump like Mity Vac. When the heater valve fails due to loss of vacuum control, it goes to full open heat. There are a number of other controls in the system as well.
Good luck,
Dave

MahoreLee

Why not Napa? They are only 3 minutes away from me. Over priced or poor quality?

And yeah a hand vacuum pump is what I just bought on Amazon. Now I wait. Thank goodness it's only 2 day shipping

SQLGuy

I bought a MityVac kit at a local O'Reilly for about $50.

I can't remember the color of the clips, but I think he's talking about the clips and the Z shaped metal arm that connect the mixer flap and the actuator for it. It's closer to the leading edge of the dash than the gas pedal. The arm hangs vertically, and clips, IIRC, to the left (driver's side) into the actuator lever. The mixer can be adjusted by popping the bottom part of the arm out of the lever and then turning the arm to lengthen or shorten it (it has a turnbuckle in the middle). The theory is that you can make up for disintegrated foam at the mixer... in practice it seems that you can get less "extra" heat in summer, in exchange for missing heat (leaks of cold air) in winter, or vice-versa; if you live in an always-warm climate, that might be fine.

jpitman2

If you have climate control, check the connectivity of the external air temp sensor in the alternator cooling duct - there is a 2 pin connector behind the left front wheel front splash shield. If this is open circuit , moving the temp selector off full cold will give you full heat.
jp 83 Euro S AT 57k

MahoreLee

Checked the vacuume check valve and it holds fine. I pumped up the HVAC source line and it holds pressure fine. However when I turn the key over to run and try and pump it back up it will not hold any pressure. Should I go on and test each vacuume hose connection?

I found a service record from the local Porsche shop with a quote for a new AC head unit. In the comments it said:

"heater valve staying on, rec flap not closing"
"A/C control valve not working correctly"

Should I still go ahead and test the vacuume lines or give in and buy a new unit?