86 944 Heater on Hot

UK952 · 08-11-2001, 10:33 AM

Hi,
I have an 86 Oval dash 944 and the heater is stuck on hot, It is a UK car, The motor to drive the hot/cold flap the other posts talk about (the one with the clip) doesn't move. (Passenger side on my car) The clip is ok. The heater control valve also doesn't move. The vacuum is present in the interior, if I remove the pipes at the bulkhead (firewall?) and join them the control valve moves.
Do I need a replacement controller or is there anything else I can try? Moving the o sliders on the controller the other flaps move around correctly.

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Tony

944lvr · 08-11-2001, 11:20 AM

I have the same problem with my 87. I fixed half of it by putting the metal rod (under the steering wheel, which is protected by a plastic cover that you have to unscrew) back into the heat clip. This prevents the heat from entering youre car. However my heat is still on fulltime and ive replaced the heater valve. My mechanic said that i have no vacuum to the heater valve but i have no idea how to fix this problem. Check previous posts on this topic they may help a bit

Andre · Andre's Garage

When is that clip supposed to move?when you move the like temp knob?

UK952 · 08-12-2001, 03:44 AM

I think so,I think it is probably related to the electrics behind the knob or a relay somewhere as neither the lever that moves the flap or the underbonnet valve (in the coolant pipe) move. I also have a Turbo so I could look on there, but it has air-con and the underbonnet valve is in a different location.

jboehm25 · 08-12-2001, 03:46 PM

I just had my heater control valve replaced to fix this exact problem. Unfortunately, the problem wasn't with the valve but rather with the vacuum in the hoses. Anyone out there know an efficient way to check where the vacuum lak might be?

SnoopDogg · 08-12-2001, 04:23 PM

hey where in UK you from, im in the UK and im lookin to buy a 944 this week... engine blown as a project.... im from Leicester, but movin to uxbridge, middlesex in a month...

944lvr · 08-12-2001, 04:36 PM

I wish i knew how to check my vacuums, i have the same problem

UK952 · 08-12-2001, 04:58 PM

I did a pratiall Vacuum check by joining the 2 pipes to each other that go through the bulkhead (Firewall?) together. (they are quite easy to access on an 8V non turbo), join them and the valve should close.

UK952 · 08-12-2001, 05:00 PM

Quote:

Originally posted by SnoopDogg:
hey where in UK you from, im in the UK and im lookin to buy a 944 this week... engine blown as a project.... im from Leicester, but movin to uxbridge, middlesex in a month...

I live near Bournemouth on the South Coast, I travel around a lot though. How blown is the engine?

UK952 · 08-12-2001, 05:02 PM

Quote:

Originally posted by UK952:
I did a pratiall Vacuum check by joining the 2 pipes to each other that go through the bulkhead (Firewall?) together. (they are quite easy to access on an 8V non turbo), join them and the valve should close.

or maybe a partial one!

SnoopDogg · 08-12-2001, 05:23 PM

as far as i know the engine is dead, cheaper to get another one... but i have found a 3.0 S2 engine with wiring, ECU, exhuust system (G reg car) for 800 pounds....

should be ok once i get it fitted into the B reg 944

UK952 · 08-13-2001, 12:53 AM

You'll probably want the brakes from the S2 as well

scottewid · 08-13-2001, 10:23 AM

I had a similar problem in my 86 951. The recirculate flappers were not working:

Take the glove box out and on the left side, under the cigarette lighter, you'll see two vacuum solenoids.
The one closer to the front of the dash controls vacuum to the recirculate valves. This one only has two vacuum lines on it. The one next to it with more lines on it is the heater valve.

The heater valve solenoid provides constant vacuum to the recirc solenoid and when you hit recirc or turn on the a/c, it opens and sends vacuum to the flapper doors. I was able to verify it was working, but the vacuum line was clogged somewhere between it and the doors. I ran a new vacuum line through the rubber grommet that goes into the battery compartment and now it works like a charm. Only problem is my a/c compressor just crapped out. Oh well, if it's not one thing, it's another!

You'll have to play around with the heater control solenoid some by experimenting and pulling some hoses off to see which normally have vacuum when opened and closed, but when you turn the temp knob to full hot, you should hear it click and re-route vacuum. If it seems to be working ok, but the vacuum isn't getting to the other side of the firewall, you could just by-pass it like I did.

If it doesn't click, the solenoid might be bad or the acc unit could be bad.

Good luck.

Ehab · 08-13-2001, 01:09 PM

this might help
http://porsche-944-garage.tripod.com/shop-manual/hvac-01.html