Help, my 944 heater is roasting me!

[silverS2]

I was 'pressing on' yesterday and went over a wide piece of overbanding which gave the car quite a wallop (enough for the CD player to skip), straight after the heater went full on to hot, I turned it down but it seems to be either full heat or cold now, there is no in between.
I've tried turning it right down and then creeping it up but as soon as it gets near half way it goews full on and stays on until I turn it right down again!

I've taken out the glovebox and had a look at the little pipe that the heater samples the air with hoping it had fallen off but it all looked fine.

Is there anything else I could look at that might be causing the heater to behave in this way?

Thanks
(Very hot) Andy

[Riverside]

You were looking in the right place but at the wrong part - there's a little plastic connecting rod that can come off or break, if you're lucky it might just pop back on

The thermistors (one of which is at the end of that pipe) tend to fail to hot too so you are thinking along the right lines but it's more likely to just be the connecting rod.

hth

[diver944]

Riverside is spot on the money.

There is a guide with pictures here (note the guide is for a LHD car)

www.clarks-garage.com/shop-manual/hvac-01.htm

[silverS2]

Thanks for the tip, I'll have a look this morning.
Andy

Exactly as described, the little arm had fallen out of the clip, 5 mins and a bit of araldite, job done (and no more roasted toes)
Thanks all.
Andy

Edited by silverS2 on Saturday 7th April 18:03

[leeb]

Hope this is ok to ressurect the old post, (shows i tried to fix it)

few issues with my early spec 85 944, main one being it constantly blows hot, wherever the temp is set too. blower speed changes, but just stays hot.

i have seen the help topic on the attachment, and although its fantastic and all makes sence, how the hell do you get to that part from the left footwell with steering wheel and pedals down there? (shoulda brought a proper rhd one i know!) is there a way in from the front?

I have also checked my fuse box, and have no fuses or holders for them for ac. i appear to have just a simple blower under the bonnet, so i dont think there is ac in the car. maybe im wrong?

any help would be much apeciated. Thank you.

Lee

[Riverside]

Never owned an early dash 944 but IIRC the heater design is one of the major differences between early & late models so check you are going through the correct diagnostic list for your model, my post above is relevant to an oval dash car.

[leeb]

that was what i thought when looking at the link, the pics further down confirmed the dash was different. Looked on the clarks garage site, and it explains the s1 dash, but not a clue how to get behind there with all the pedals etc in the way. i will have a look to see if the front comes off tomorrow. warm air is good tonight, but come the august trip to the 'ring, that will be bad news!!

[924racer]

I remember removing the heater from a 924 (with same dash) and i seem to recall its a very simple cable operated flap which opens upwards to allow air to be drawn from just under the bottom of the windscreen. If somethings happened to the cable the flap would just fall shut - allowing no outside temp air through. This is really only a guess though so your best bet is to get hold of a 924 haynes manual as this will have the correct info for the earlier dash.

[leeb]

in case anyone else has this problem, i have found this link, havent done it yet as its p1ssing down outside and its 8am!!! hopefully will later though.

http://www.kronowit.com/porsches/944-heater-fix.ht...

Can anyone confirm if all 944s had the Air con? or will it be a simple case of heaters and cold'ish air? this lack of air on fuses is bugging me. Cheers



Edited, because i have just gone and got wet, to realise that it loos nothing like the one in this link, i think this link is the 85.5> model. not the early one. GOOGLE............

Edited by leeb on Sunday 16th March 08:17

[james0]

On the early dash car first place to look for heater issues is the engine bay.
At the rear of the engine is a plastic valve which is controlled by the cable from the dash, the arm can break off or cable come unclipped.

[leeb]

this dam car!
james what you say is spot on, me and a mate today hunted all around on the hunt for the broken clip which could be causing this as that made perfect sence. followed the "hot/cold lever" cable, out through the front of the car, into the engine bay and tested it with one watching the other moving, and the clip is all intact, and moving apparently how it should be. all of the cables are connected as far as we can work out, and all valves opening properly. we are just getting no cold air blowing through!!

checked all the fuses and no problems with them. could if be a relay? Im wet, cold and i havent fixed the dam problem!

[james0]

Is it definatly an air con car? That valve should stop the hot water to the heater matrix and you should get cold-ish air, if not i would say the valve was shot. never had a car with air con but i do know that the compresser sits above the alternator under the air box

[leeb]

i would say it is a 'no air con' based on te fact there is no fuse 5 or 6 which are the air con fuses, and the settings on the heater have just a turn knob with 0,1,2,3 and a slider from cold to hot. doesnt look like air con, but even without ac, the temp coming into the car on cold, should be relitavly cool should it not? it was pooring with rain and about 5'C here today.

[james0]

Replace the heater valve, its a cheap part its probably letting by, you may want to try to dissconnect the cable and turn it manually as there is a possibility that its not closing completly when pulled/pushed by the cable.

[leeb]

cheers mate, i will have a look over this weekend. sorry to be thick, is this heater valve under the dash, or the part i can see moving at the rear of the engine bay?

[james0]

It's the valve in the engine bay

[kevstor996]

My heating is driving me nuts right now (1986 2.5 lux), late dash model, with being on hot the whole time! Ive gone through the system as best I can and worked out the following:
- tested vacuum valve in engine bay - works fine if I suck on it or if I bypass the internal pipes and hook the brake vacuum directly to it
- swapped out both solenoid valves under dash
- swapped out heater control unit with a 2nd hand one and now when I hit the recirc button I can feel the rear solenoid work and recirc circuit works properly
- no matter what I do with the heater knob it just blows hot air constantly - solenoid doesnt feel like its switching at all

I realise the system defaults to hot if theres a problem. All vacuum hoses seem to be ok. not an air con model as far as i know, no compressor etc. All clips on left hand side of dash are ok and intact.

Only thing I can think is that the heater rheostat is broken on my new 2nd hand heater control unit - Ive tried 3 now so would be damn unlucky if I had 3 failed units? Either that or theres no +ve feed coming in to the rheostat that should then go out to the solenoid when the temp control is set to cold? As far as Im aware there are no hidden fuses anywhere to check..

Any help appreciated as Im not sure what to do next and cant afford to keep buying heater control units!

[Pope]

Quite the thread ressurection!!

Have you checked the mechanism beside the glovebox? The mixing flap is connected there.