Help re: A/C

Sam Lin · 07-15-2003, 10:53 AM

Hi, my A/C doesn't ever blow cold air. I checked the numerous web pages explaining the broken clips, and the right-side clip is broken, so I've got a new one on order. However, in the meantime, I was thinking I'd just find what position everything was supposed to be in for the full A/C settings, and cable tie everything in that position - when I moved the switch and sliders on the A/C control, the left clip's stepper motor moved it up and down fine, but the right stepper motor (the one connected to the broken clip) won't move at all! Is it dead? What should I check next to make sure?

Also, I just looked through my Haynes manual as well as my parts/technical reference, and I can't seem to find a part number for that right stepper motor if indeed it is fried.

(by right-side, I mean the one towards the rear of the car)

Help please!
Sam

Scott R · Scott R's Garage

From your description you have a post 85.5 model 944, so that being said the stepper motor that appears to be dead is controlled by the climate temp knob on the climate panel. Turning the knob hot or cold will actuate this motor.

Sam Lin · 07-15-2003, 11:25 AM

Sorry, forgot to include the car is a 1986 944 Turbo.

I had my brother move all the adjustments while I stuck my head under there and watched, (the upper/lower sliders and that temp knob with A/C on and off,) but that stepper motor never moved?!

I'm in Arizona, where it was 90 degrees at 5 AM today, so special thanks for the help!
Sam

Sam Lin · 07-15-2003, 11:30 AM

We just went out and tested it again, it's confirmed - that rearward motor and arm won't budge no matter what we do with the controls. I can't get it to move pulling on the arm by hand either!?

Sam

Scott R · Scott R's Garage

I had to open my motor up and clean it once. It was sized but since I cleaned it up, its worked great.

Porsche944 · 07-15-2003, 09:22 PM

Since you are in Arizona I would guess that the outside temperature sensor and the cabin temperature sensor may be inhibiting the heater.

A better test is to hit the defrost button. When you push defrost, the heat is automatically switched to high regardless of the ambient temperature, and the A/C is kicked on.

BTW: I'm a native of Arizona. Born in Williams and grew up in Flagstaff, now retired and living in Charlotte, NC.

Sam Lin · 07-15-2003, 09:48 PM

Update: I safety-wired the arm in the proper position, but I'm outta Freon. Ordered a R134a retrofit kit from eBay, will be trying my luck with that.

However, that leaves the problem unsolved. Scott, per your recommendation I took the motor out, opened everything, rebuilt it, the motor works fine when I direct jump it, but won't run when I plug it in. Does anyone know what the voltage readings are supposed to be for each of the 5 pins in the motor's socket? I got voltage on every pin so I doubt it's that problem, leaving the problem being the circuit board in the stepper motor box. Anyone know the part number for the whole assembly? I couldn't find it browsing listings anywhere.

Porsche944, what should I be looking for when I hit the defrost button?

I really appreciate the help!
Sam

Porsche944 · 07-16-2003, 07:24 AM

When you hit the defrost button the heat should go to full hot, and the A/C should kick in. Of course with the temperature mixing damper wired shut you won't feel the heat.

According to the factory manual prints the servo motors get 12 volts and ground on pins 4 and 5. Just swap polarity to get the motor to turn the other way.

Be sure to get a new reciever/dryer (Try this link: http://www.performancemotorcars.com), use low pressure air to blow out any remaining R-12 oil, and disconnect and dump the compressor. After that you can put the system back together, have it evacuated, and then charge your oil and refrigerant.

If you have any serious questions about working on your A/C system, talk to Griff at 800-451-7225 http://www.griffiths.com/

Sam Lin · 07-16-2003, 10:09 PM

Thanks Cliff, I will try the defrost idea.

The servo motor isn't moving, though I did get a voltage at the plug to it, will check again if I get 12v between 4 and 5. Could it be the A/C control unit gone bad? Any idea of where I can get a replacement for the servo motor assembly, and what the part number is? I have the parts/technical reference and either they aren't in there or I can't find them!

Per your recommendation, I just ordered a new reciever/dryer from that link.

Griffith's site is down now, but I've bookmarked it in my list of Porsche links.

Thanks for your help.
Sam