Porsche Enthusiasts Club Forum

No it was not an ac unit, butitwasthe later type with numbers, I am still of the opinion that the sensor connectors are present, they should be connected, with out the input from those how does it know what to do

Really would be great if someone on here had a similar set up so could check & compare!

I still think the parts missing are

911 624 065 00 fan and sensor
944 572 529 00 Hose

the under bonnet sensor, handily is listed by Chassis Number

944 653 123 00
F >> 94-KN404 397, 944,944S2

964 659 120 00
F 94-KN404 398 >>

so if the Chassis number falls in one of these ranges, it really is missing a sensor, and the cable tie in the picture looks out of place

the early sensor has been superseded by the 964 number, and they are £45.00

there is a repair Kit for the Mixing chamber sensor, PCG 653 121 00 @ £103

and the under dash fan mentioned above is £172.00

as for the controllers

08/84 to 07/88 944 653 021 02
08/84 to 07/88 944 653 021 03 M424, Found on Stuttcars 424 Automatic heating control
08/84 to 07/88 944 653 021 04 M573 (airCon)

08/88 to 07/91 944 653 021 03
08/88 to 07/91 944 653 021 04 M573

not a lot to choose from.


the 968 one I sent him.

944 653 021 03 01C

so the same device just with a different face plate.

and that's it for Oval Dash Cars, Square Dash is completely different

I pulled the dash vents off again today to double check there is nothing there, there is a clip in the molding in the collector area but nothing in it or even in the vicinity.



I was thinking the way mine works is just by opening/closing a flap to regulate how much hot or cold air was let into the cabin when you turn the knob, I assumed the later one with temperature figures on it was a more accurate system and then would need sensors to reflect what was on the knob?

so the idea of posting the chassis numbers would give us a clue if these sensors were fitted to your car or not,

I cant see any reason why they would use an electronic controller that needs all those sensors and then not fit them,

as the clip is there ????, the under bonnet connector is there, is there a plug for the fan unit and for the mixing chamber sensor?

does you chassis number fit in either of those two ranges

as for numbers v red/blue I dont think there is any difference as all 968 except sport and CS had numbers, but the basic controller was used in the sport and CS,

there are only three different ones from 1985.5 to 1995, wonder if it was used as a parts donor at sometime?

I didn't have access to the chassis number when I posted my last post but I have been to get it today.



My chassis number ends with ***********400330






This is something that hadn't crossed my mind but its a quite original and unmolested car but you just never know I guess?

So with that chassis number it should have the early one, that has now been changed to the 964 part number one

be nice if we could find some bits to borrow

I'd love to have a nosy around another S but I never see another one around at shows or anywhere really.

I will be on the look out the next club meet!

The last and possibly only other one I've seen was at Oulton Park RS day last year, a guy had driven over from Ireland for the track day (just to spectate) and parked directly behind my garage. I'm not sure if he'll be there again this year but ideally I'd like to sort it out before March?

Finally, I can post again!

Managed to hunt down a 944 S with gradual blue/red heater control unit; no temperature numbers. It was at a friend's MOT station. As far as I could see, there was no thermister at the fan inlet under bonnet, or the one with fan/tubing to small dash vent behind glove box.

Hope this helps.

I wrote an update with pictures a few days ago but it wouldn't post



That info does help, and I think how mine left the factory, I wasn't sure the next time I would see one in the flesh so wasn't sure if I should buy all the missing parts or not?

Actually, managed to see another 944 S on Sunday where we have our regular Sunday morning unofficial cars & coffee gathering.

I don't think you need those parts. I could also see the plug behind the glove for the thermister fan/motor, so most prob not used in this set up.

I had read back through this thread and Waylander originally suggested, the vac valve by the oil filter may be one culprit, so I decided to change this anyway, my original one seemed to work fine but I just wanted to eliminate it.



I fitted the new one and noticed the joint elbow was quite loose and not a great seal, I did think this may have been causing the problem but again it didn't cure it!



I have given up with it for a little while and have refitted the glovebox and left the heater flap bar disconnected to allow warm air into the cabin. I will get back on it in the Summer but I'm not holding out much hope.

I have got back on this now the car is sorted out in other areas, with the engine fully warm and on idle at 950 rpm I decided to check the vacuum on the brake booster, which is reasonably close to the inlet manifold. I got the reading you see in the picture below, its not in the green area so I'm thinking it is too low? Is this enough to affect the heater system from working?



Once the engine was turned off the vacuum dropped to zero within around 45 seconds, I'm not sure how long it should hold for if at all, considering the throttle body could leak vacuum easily, I've not found anything regarding how long it should hold for?