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A lot of hot air

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Hi All
Hope some one can answer this query, having just bought my first Porsche, an '86 944 which is great fun so far...
I can only get hot air out of the heater whatever the temperature control or vents are set on. I'm told the heater control valve needs replacing... is this right?
My local Porsche specialist guy has changed the valve once but it didn't cure the problem - he said it must be a faulty valve and is ordering me another one. Is he right?
Any ideas would be much appreciated.
Many thanks.
Steve
 
The heater fails to hot if it has a fault. It could be the controls or pretty much anything else in the system too. A common failure is the plastic clips that hold linkage rods together down the side of the glovebox but usually the symptom there is random temperature variation rather than just hot. Worth a check though as it is pennies to replace them.
 
If the white plastic actuator clip is broken you get hot with any setting other than cold and cold with cold.

It is possible to see the actuating rod if you look up between the side of the glove box and the heater controls, but it is probably easier just to remove the glove box. Be careful as it is easy to earth out the glove box light.[;)]
 
If you are referring to the control valve between the bulk head and the engine, this seldom goes wrong other than leaking. Its main function is to stop the water flowing through the heater matrix until the engine warms up although it does open and close with hot and cold settings, the main temperature controls are pneumatic operated flaps.
As John and Fen suggest I would check the white plastic clip. Mine first 944 was on fully hot even when set on cold, drove it for 2 weeks with the windows down until I fixed the clip.
 
After removing the glove box you will see
Rod A, should be held by clip B

60C37B613F2349939554492C039F6DB6.gif
 
I didn't realise you got full hot with a broken clip. The only time mine has failed (first 944) it would go hot under acceleration and cold under deceleration (might have been the other way round). At constant speed it worked not to badly as I recall.
 
Welcome Steve - good choice of car [;)]

If your specialist did not know about this 50p clip then I think its time to look for another specialist [:D] Many of us on here have had to change this clip - both of mine have snapped since I've owned the cars
 
Chapelgate OPC didn't know about it when mine went. They recommended a new control unit which at that time was very expensive even from a breaker. I got one from Douglas Valley for £450 and it made no difference of course. Fortunately they took it back, which moved them up in my estimations. I never went back to Chapelgate.
 
I didn't realise you got full hot with a broken clip. The only time mine has failed (first 944) it would go hot under acceleration and cold under deceleration (might have been the other way round). At constant speed it worked not to badly as I recall.
Click to expand...
[:D]Just thought.......

My rod might have dropped and wedged.

Fens rod [;)][;)][;)] was dangling loose (as usual) and was opening and closing by G-force (or should that be string[:D])

Mike[:'(]
 
Many thanks all for the helpful advice... I can see I shall be spending some time grovelling around in the glovebox the next couple of evenings to hopefully sort this out!
 
The heater control on my 944S is digital. In the off position it's completely cold. If I turn the knob to about 9 o'clock, it goes from full cold to full hot (and very hot it is too).

I'm [pretty sure that it's just a worn valve. Is it an easy enough job to replace it? The car is my daily driver, so it would be nice to have some better resolution on the heater control [&:]
 
In answer to James
Assuming you have the temp control wth numbers on then it is probably one of the thermocouples. IIRC there are 3 one in the middle of the dash somewhere, one at the end of the pipe that goes from the small round grill above the glovebox and one in the scuttle area. It is usually the outside air temp one that fails. I haven't had this problem but I believe Diver944 has and knows more about it. It may well have been discussed here before a search for 'thermocouple' shouldn't bring up too many other threads.

Back to the original post, If the plastic clip is OK it could be one of the servo motors jamming - My lux did this, If the clip is ok I will post details of how to check the motors.

Tony
 
I have the dial without the numbers, so I think that means it's just a dumb valve. It's probably just a bit worn and letting too much hot water in when it's opened a fraction.
 
I may still be that the valve is either open of closed and the temp control is stil by blending outside air with warm air passed through the matrix. I have never had the blue/red graduated heater though so I could very well be talking nonsese and ususal.
 
Might be worth checking for a vacuum leak, under the bonnet and in the drivers footwell, and yes the lever where the plastic clip brakes is supposed to blend hot and cold air to blend the correct temp so this could be badly adjusted or the motor might be doing strange things - It should move smoothly and linearly as you move the knob from blue to red.
Tony
 
Well well!
Guess what I found - one dangling rod and one broken clip!
Hopefully a new clip should cure things.
The end of the rod is 'threaded' - I assume this is where the rod is held in the clip? It's a bit difficult to see from your photo?
Thanks for the help.
 
Thanks Paul
Er... what's the OPC?
Sounds like one of those awful American teenagers programmes they have on Sky TV.
Official Porsche Centre?
Going to the Porsche main dealers in Belfast tomorrow to order the offending clip. Spoke to their parts guy this afternoon and between us - me trying to describe the parts without knowing the proper names for them, and him trying to magnify his fiche - we decided it would be easier to sort it out in person!
 
ORIGINAL: JamesH

The heater control on my 944S is digital. In the off position it's completely cold. If I turn the knob to about 9 o'clock, it goes from full cold to full hot (and very hot it is too).....
Click to expand...

It could be that I didn't remember the sequence, as noted above, and a broken clip gives you cold until you turn fully hot. Either way it sounds like the air blending and thus the lever (and hopefully clip). This is very very common (happened to most people I've spoken to) so I would start there.
 
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