redhorse

Has anyone ever repaired a late 944 or 968 heat and air control unit? By that I mean, you either replaced some discreet components or one of the pushbutton switches. I am looking for feedback on what is possible and hopefully the schematic of the switch itself.

Seems these cars are notorious for switch buttons that lose the ability to stay in the "on" position (looks to be the fault of a small piece of white plastic that wears). I have searched the web and only found one article that looked like someone was trying to repair the switch, but it was in Japanese or similar language I couldn't read.

Also, on reading some parts sources for AC replacement switches, I see disclaimers that the part is for control units that have removable switches. What does this mean? Did some control units come from the factory with plug in sockets for the ac switch? All of the units I have seen have the switches (ac, fan control, temp, recirc/defrost) soldered to a base circuit board.

After disassembling one non-functioning ac switch while it was still soldered on, I am of the under-informed opinion that the switch cannot be repaired, only replaced. Odd to think that a switch that is so easy to wear out, and has hard mounted lights in it (that burn out at some point) would be so difficult and expensive to replace.

Does anyone have any experience with any of this that they can share? I know there is at least one entity out there that repairs these control units, but they are priced high enough that I would rather purchase a discounted new unit or better still, install a substitute. Has anyone found a schematic for the circuits boards in the control unit? I have an electronics background, and would like to reverse engineer this unit and design an interface to a replacement that fits the same opening. Give the parts on the control unit, and the lack of enduring quality for the main components, a new 'non-Porsche' system like it should not cost much over a $100.

Thanks!

Grandpa#3

Go on ebay and buy the entire control unit. My A/C switch cover fell off. I payed $46 for a used complete unit and was lucky at that price. You just have to keep looking as some want over $200 for a used one. You could try using the "Search " at the top of the page and type in: A/C Switch. It just might bring up a past post of it. I looked at my WSM wiring diagram and really could not tell except it goes to the low pressure switch then to compressor. Nothing is marked on the layout of the Heating and A/C panel as to A/C. I read somewhere that you have to unsolder the switch to replace and another is plug and play. The switch itself is $89.00. I'll look around and see what I can find for you.

Cheers,
Larry

PeteL

I replaced the "snowflake" switch...or more correctly, someone did it for me.
You need to unsolder the old one and solder in the new one.
But it is doable, and probably for a lot less than a new control unit.

redhorse

Hi Larry...any information is much appreciated. I have looked at every switch offered on eBay for almost two years. Most sell for way too much money in my opinion. But, I bid and won two and now I am totally annoyed because both sellers lied about the condition of the switch (one of those sellers is a regular on this forum, said his reputation meant a great deal to him....yada yada...). Being electro-mechanical, it is easy to tell if the switches don't stay in the 'on' position.

I have three units total, one being the original in the car. It works properly (knocking on wood) but the plastic is broken. I am replacing the dash and will replace the clear plastic mounting face. To do that, I have to unsolder and resolder the switches on either end -- man, this is one of the most poorly designed items I have ever seen -- both for reliability and for repair. But maybe I will repair one of the others I purchased by replacing the switches that have to be removed to mount the plastic, with new parts. I got lucky and bought a new ac on switch (the snowflake) for $49 and continue to look for a good price on the other.

But, I am still inclined to find a custom ac & heat control unit to replace the factory unit. Accordingly, the reason for the control unit schematic is to learn what the controller does. I fear it may be part of a weird combination of things including the temp sensor mounted in the dash. But, I want to give it a try. I do have the electrical schematic for the car, just not the control unit.

Grandpa#3

Yes, I know of the person who thinks his stuff is made of gold and always top notch. I would like to buy some things, but way out side my budget and outlandish s/h charges. Everyone has to make a living one way or another. The automotive engineers do not design car parts to last beyond 10 years and also to make you go to the dealer for car repairs. Oh well, such is life. I hope you can come up with a new switch layout.

Cheers,
Larry