Fixing up the climate control head

[kdjones2000]

The mounting point on my climate control head, like many others I am supposing, had been degrading over the past several years. Having these recessed holes for the mounting screws only leads to stress crazing in the acrylic, ultimately leading to failure of the mounting points. The tipping point for me was when the third hole died and my last attempt with epoxy failed.







The mounting plate is actually a separate part number in PET, but is now NLA (944.653.911.00 and 944.653.912.00 for M424/M573 Automatic control/AC). I therefore picked up a "parts" unit with passable mounting points and started to work on the swap. This turned out to be quite a bit more involved than I was initially thinking, as shown below...

First things are to remove the case around the unit. I found that the best way to do this was use a small screwdriver and go through the openings in the clear plate to gently bend back the tabs, and carefully work the back cover off. The fan switch knob requires a thin screwdriver to pop it off as well.







Once the back cover is off, the scope of what is needed to be done becomes apparent. The clear mounting plate is held in by both the Recirc/Defrost and the A/C switches. Both of these are soldered to the middle PCB, which is then glued to the top and bottom PCB's in the assembly. The only way to get the clear mounting plate off is to desolder the multiple connections for each switch and remove them. The glue used to hold the PCB's together is a putty-like material that can be fairly easily removed with a pair of needle-nosed pliers. Once that material is removed, I used a desoldering braid to remove the solder at the connections. It is difficult to get under the solenoid on the left side enough to get at the lowest post, but if you have a small enough soldering iron it can be done.







Be careful you don't heat the switch posts up too much or you can melt the supporting plastic. Remove the hex nut and washer on the temperature pot. Once this is done, work the switches out of the PCB and you can carefully remove the clear mounting plate with the switches, or do the switches first and pop out the mounting plate.

[kdjones2000]

Now is a good time to look at the various light bulbs in the unit and try to replace them if necessary. My unit had no issues, but the parts unit had 3 bulbs burnt out. Replacing these will prove to be challenging as they are very close to the posts and almost inaccessible.







It's also a good time to check the bulbs in the switches themselves, as there are no fewer than FOUR in the Defrost/Recirc one (!) Again a thin screwdriver is used to pry the back off the switch casing. Be careful not to lose the springs.



After disassembling the parts unit in the same fashion, the good mounting plate is snapped into the front of the unit and the switches carefully inserted through the PCB. I had to clean up the PCB holes and the switch posts with the soldering iron to make it so that things went together easily.



Carefully solder the switches back to the PCB, making sure not to heat up the switch posts too much.



I used hot glue to hold the PCB's together instead of the original urethane.



The unit all reassembled and ready to go back into the car.



And finally like it should be again!



This is certainly not for everybody, but if you are handy with a soldering iron it is not so hard to do.

Cheers, Keith

[kdjones2000]

On a further note, the parts unit I acquired had apparently failed at a trace on the upper PCB, and if yours is not working then I suggest you look to see if this is the reason. Repair is quite simple, just scrape off the solder resist and solder on a jumper wire.

[Grandad#3]

Great write-up with clear big pictures. This should be put in the DIY Section. I think I could do the job now with your info to work by.

Cheers,
Larry

[944 Ecology]

That upper trace failure is caused by a short in the AC clutch circuit. It took me burning out four of them to figure out what was going on.

[968 GUY]

New, clear plates used to be available from 944 online.

[kdjones2000]

Thanks for the info, guys.

I just took a look at Ian's site, and it seems that he is still selling a European version of the clear plate:

A/C Control Clear Face Plate: This is the european version. The difference between this one and the US version is that there are no numbers for the temperature knob. The US version is no longer available from Porsche. $70

I just checked the ROW PET and it has the same part number for the face plate as for the USA, so Ian is getting this part from a 911 or the like, but it's good to know that at least something is still out there if needed.

George, thanks for the tip on the failure point. I was wondering if there was something else that could have caused it, or if this happened on its own.

Where is there a DIY section on this forum? I sure haven't seen one in the past 5 years....

Keith

[Aufgeladen944]

Alright on my car, I have no climate system at all. No temperature adjustment, no defrost, no recirculate, no compressor turn on, no nothing. The only thing I have is to adjust the fan speed.

I was thinking of swapping out this unit. I am NOT handy with a soldering iron. If I pick up a used unit, will it just plug in? Or is it all soldered connections behind there? I don't wanna crack mine open or anything, I just don't have the steady hands and patience required for this kind of work. Sorry!

My car is atrociously hot in the summer and I can't take another summer without a/c.

[kdjones2000]

The unit just plugs into the wiring harness with 3 or 4 connectors. You can see the posts here:



Cheers, Keith

[Stephen03]

My defrost switch wont stay latched anymore, I took the climate controller out but couldnt get the switch out easily to look at it. Do you think it can be repaired? Looks like alot of work to get at it.

[stogie25]

Nice job. Great pictures.

I took mine apart a couple of years ago when I switched to blue LED's. It was a bit of a fight to get it apart, but overall not a terrible job. Knowing how to solder and desolder is very helpful.

[kdjones2000]

Originally Posted by Stephen03

My defrost switch wont stay latched anymore, I took the climate controller out but couldnt get the switch out easily to look at it. Do you think it can be repaired? Looks like alot of work to get at it.

You will need to desolder the terminals for that switch to remove it. The procedure is shown in the pictures above.

Good luck, Keith

[ghostpixel]

kdjones2000,

Thanks so much for this awesome post! I had to swap out the clear mounting plate on my TCU and this really helped.

[Tom944]

Great write up. Can you tell me where to get the internal switch bulbs (ac, recirc, defrost). I would like to replace mine.

[Gawernator]

There's a post DIY in replacing the bulbs with LED's

[kdjones2000]

I am pretty sure you can get the bulb for the fan switch from a NAPA dealer, as I bought a similar replacement bulb from them for the headlight switch dash light.

The other bulbs are all soldered into the PCB or the switches. I don't know of a source for these or their wattage. Maybe an LED conversion might be a better bet, although I don't know how you can get a soldering iron into some of those locations to remove the original bulbs. Some of them are actually between the terminal posts - very hard to get to.

[J1NX3D]

great write up!

i was going to say the same thing, a replacement is available from ian at 944online.

this are the two I was mucking around with at Christmas. the front one is from my RoW '86 n/a, the back one is from my ex-Japan '964 968 parts car.

[Tom944]

I would like to replace the switch bulbs with bulbs rather than LEDs. Desoldering and soldering will be no problem since I have precision tools for that at work. If anyone knows the Wattage for the bulbs let me know?

[Xanadu]

Hello, great photos and instructions. Just want to you there is another version of the climate control head. I'm working on my 1985.5 944 and pulled the unit out as it had burnt up! This unit had a "plugin face." It came off very easy, and then the switches could be removed by just speading two holding tabs.

[mytrplseven]

Do you know what year the plug in switches work with? I have an '87 N/A and have two parts units to draw from while I'm restoring the climate controller for my car.