Heater Stuck ON!

[neikoh]

The knob on the temp control is frozen, and the heater is always on.
PLEASE HELP!!!

1989 944 2.7L

[mytrplseven]

Go under the hood behind the motor and there's a small valve that is the heater valve. Pull the linkage from the mechanism. Be careful not to disconnect any vacuum lines. Then push the lever from the position it was in when you found it, to the other position.

[Grandad#3]

The valve "mytrplsvev" is talking about is The Vacuum Heater Control Valve. The link below is the valve.

Porsche 924S/944/968 Heating & Ventilation - Page 1

Cheers,
Larry

[944tothefloor]

Sometimes you can remedy the valve by turning the knob back and forth every few seconds while driving.

Or your problem is the "door" under the dash board. A plastic clip occasionally breaks and and then you have constant, full heat.

[mhariush]

It's prob the little plastic clip under your glove compartment.

944 Heater Fix

[Jfrahm]

I think the poster said his temp control knob is frozen, which should be considered as a potential problem before one addresses the plastic clip or whatever.

The water valve can be tied shut with a ziptie while you get a new climate control unit to deal with the stuck or broken control knob. Make sure you get a later 85.5+ control unit, the earlier ones look the same from the front but are larger and have more antique electronics inside. I am not sure when the change occurs, maybe 1987. The 968 unit is nice too, it has a detent pot for temp control.

If you have other problems after fixing the climate control unit you can look at the usual suspects, the valve itself (which can leak hot water even when closed) or the heater clip which I am told breaks but in 15 years and 6 cars I have never seen one break myself.

-Joel.

[mhariush]

I see, I read it as "frozen" meaning nothing happens and always on hot... got it If it's the case of the knob being stuck, i'd get a new unit to try...

[neikoh]

where do i apply the zip-tie? to the larger hoses? Do I keep the vacuum line attached?

[neikoh]

Temp knob is still stuck. What I did was swap the support that was good from the mixture control to the heater "Flap/door" controller and pushed the linkage till the door closed and attached to the support. Time for a test run...

[Jfrahm]

I do not have a 944 heater valve handy but to zip it shut you pull the arm in as if there is vacuum to the actuator and tie it that way. That should keep hot water out of the heater core unless the valve is passing hot coolant even when closed (I have had this problem.)

If you are back there I suggest replacing the heater valve with a stronger aftermarket version unless the Porsche valve is quite new. They can crack and dump coolant. There are a couple aftermarket valves which I feel are stronger. Ford Escort, Audi 5000 fitments I believe.