Mark Parker

I just last week bought an 85.5 944, a little rough, but it has potential. I recieved no owners manual, and as I am tweaking and evaluating I find that the heat stays on constantly and the temp doesn't seem to respond to the **** on the climate control center. I am getting an owners manual so that I can figure out how the thing is s'posed to work, but in the meantime, can anyone give me some tips on what might be amiss. Thanks.

Melchior

Go to www.paragon-products.com and click on tech sessions. There is an article listed on how to fix the heat mixing lever.

johnmshaw

Hi there are small white clips in the climate control unit box(sorry don't know tech name) it's located in footwell on drivers side near accelerator pedal. one or both have broken and this is why you are being blasted with hot air. cheap fix parts avail at dealer not sure part#. Good Luck and enjoy your car. John 86 951

Mark Parker

Thanks much for the tips, I also stumbled on the same late last night as I wandered bleary eyed through the archives. But it's good news, bad news for me. The good news, the clips are intact, the bad news of course is that I still have my problem. I am beginning to fear the worst. I have taken the CC unit out and inspected the terminals on the harness plugs. They look to be in good shape, but I put a little dielectric grease on the pins anyway and reinstalled it. I understand from what I have read in the archives that as I move the two sliders on the unit, I should get a corresponding change in the air output from dash vents to floor, but I don't get any change at all. Could I be lookin' at a bum CC unit? Thre fan works fine BTW.

Magown

Mark, if you lay under the dash and have the little black cover off, you should see and hear movement from the arms moving as they change the position of the flaps. Also your heater control valve should be shutting too. If the valve isn't opening and closing and the arms aren't moving then you have a problem with the control unit.

Rolfe

Hi Mark, I had exactly this problem when I bought my S2 convertable. I traced it to the rubber hose that fits onto the dashboard that acts as the cabin sensor. This was bunged up with fluff. I cleared it and it all worked fine. You have to admit its a good heater though!!!

Tom

Also bear in mind that what may seem to be a problem may be normal. When it's cold, I sometimes think my 944S is broken because as it warms up, it blasts out hot air. This usually continues after I think it should stop. Then a little later I will notice that I only get cool air. The reason is that the temperature is thermostatically controlled (the numbers on the dial are degrees Celcius). It puts out a lot of heat until the desired temperature is reached, then cools off. 72 degree air actually feels cool so the proof is if its cold outside and I'm comfortable, even if it feels kind of drafty. I also don't notice much of a draft out of the floor vents. The defroster vents are easier to check. Also make sure the defroster is not on. It automatically sets full fan and full heat, can't leave it on long but it does clear off the windshield. The button below the defroster is for air recirculation in case you're stuck behind a bus or going past a hoglot.

Mark Parker

Thanks to everyone for the tips. I've checked the clips under the dash and they're fine, and my heater control valve holds vacuum from a hand pump, but the CC unit gets no response from any vacuum motors. I pulled out the sampling fan and in fact it was clogged, but the motor itself seems quite stiff, and the harness to it indicates only 1.5 volts available. The fan will run on 12 volts when jumpered to the battery, but I'm satisfied that it needs replacing.I am still going to check the other two temp sensors for general condition, but I can't help thinking that even in the default full hot mode I should still be getting some reaction from the fresh air intake and vent/ heat doors, and I get none. I'm afraid Stephen has pegged it, and I may very well have a bad CC unit. But then again "bad" may be a relative term. I know some pretty sharp electronics guys, and it may be something they can fix. In the meantime the quest continues. If anyone knows of a better schematic of the CC system than the one in the Haynes manual, I'd appreciate the info.

Adrian

Dear Mark,
The Haynes stuff is useless. I have the manual myself and well I could have done without spending the money. Now I have never seen the 944 data available however I do have the 964 data from www.alldata.com They should have a full set of factory wiring diagrams on the 944 part of their site. It will cost you money to subscribe (About $24:00 I think now) but if the 944 stuff is anything like the 964 stuff I think you will find it money very well spent,
Ciao,
Adrian
911C4

PS: My 944 had the same problem and it turned out to be the servo valve which mixes the hot and cool air. It was stuck in the full hot position. I also played with the vacuum source and thought I had repaired it. The very last thing to replace is the control unit. 9 times out of 10 they are perfectly serviceable.

Mark Parker

Adrian: Your suggestion about Alldata is very good. As a matter of fact, one of my co-workers used to be a subscriber to the professional version (we are in the auto repair trade, but we now work on fleet equiptment for the U.S. Postal service and don't need outside sources) so he let his subscription lapse. I looked into the DIY version, and it would be perfect but for one thing. My wife currently drives a '98 Chevrolet which she is QUITE unhappy with, and she really wants a BMW. Unfortunately, I see that the DIY version of Alldata specifically leaves out that Marque. I have e-mailed the man they say is my sales rep and asked him to quote me the price of a professional subscription, but if I'm not mistaken, it is high. I may just go with the DIY, $24.95/year plus $11.95/year for each additional vehicle. Meanwhile, back at the ranch. I am hopeful that, as you say, my problem is somewhere other than the CC unit, but I have a line on a used one just in case. Meanwhile, I think that I'll make a batch of Christmas cookies,,and take them for a ride to bake..... Mark

Adrian

Dear Mark,
Good luck. Always start with the simple and work towards the most expensive. Despite what you hear, Porsche/Bosch/Teves control units are very reliable. A general visual inspection can often find the fault.
Hope the biscuits turn out well for you,
Ciao,
Adrian
911C4