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Wayne 962 Wayne 962 is offline
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Here's the AC control unit with the face removed. Two screws, and it can be lifted out.

I removed this small plastic piece in order to make it easier to slide out the control unit. I didn't want it to get scratched.

Here's the unit removed. It's a bit more complicated than I expected it to be. Let's hope the insides look a bit simpler. After all, it's just a switch that takes in 3-4 temp sensors, and controls a few valves and relays, right?

Here's the back where the three harnesses connect to. Note the 959 part number which bodes poorly for availability.

Hmm, this doesn't look factory. Looks like someone has been in here before and marked the harnesses with some type of white marker.

Okay, time to check the temp sensors. All three read the same value, which was on par for room temperature. When I started and ran the car, the values went up as the car got hotter. All three seem to be working well, which is disappointing, as they would be easy to replace.

The other end of the multimeter goes into the electrical harness to check the resistance. The factory manuals tell me which pins to check. The 959 manual, suprisingly, is very well written with lots of detailed information on how to troubleshoot most of the stuff on the car. Since this is similar to identical to the 944/968/928 climate control unit, I will check my other manuals tomorrow to see if there is any more additional information I can glean on the system.

HA HA. Jeepers, This is a mess and looks complicated. The factory workshop manual told me to remove harness "R" and check pins 12 and 13 for voltage and resistance of the heater coil (harness "R" is on the right - the black/pink one that is disconnected). Note the crappy alarm system wiring on the left - we'll have to deconstruct that one day in the future, but first things first. That cable hanging down in the middle is the antenna cable from the radio. The harness checked out with the proper resistance values for the coil in the water valve, so that means the wiring is good and it's connected. It did not check out for power to the coil, which means most like a problem with the control unit.

Back at home, here is my control unit on my workbench. Crap, this thing looks complicated.

Prying off the clear plastic lid takes patience - you don't want to damage this thing, as it's likely that it's unavailable. Unfortunately, there are signs that it's already been opened (bad sign).

Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series 101 Projects for Your Porsche 911 How to Rebuild & Modify Porsche 911 Engines 101 Projects for Your Porsche Boxster & Cayman 101 Projects for Your Porsche 996 / 997 SPEED READ: Porsche 911 (October 2018)

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Old 10-25-2007, 09:34 PM
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