Swapping 964 CCU for 993 CCU..help
 

I have a 91 964 with a confirmed bad ccu.

I read that a 993 CCU is interchangeable save the max ac button. My indy swapped it and says that the fan is stuck on high while the 993 piece is in. He had a working 964 CCU he tried and it works fine.

Is anything necessary to change before swapping to the 993 piece for it to work properly?

Any help to make this 993 piece work would be greatly appreciated.

thanks

You need to jump two wires
See Tore Bergvill

Thanks 964TargaC2.
There's a bit more to it than this. 5 to 7 wires needs to be changed/worked on in the car harness in order to get a 993 CCU to work in a 964, depending on the 993 model it came from.
You'll have to decide on either changing the wiring harness or get your 964 CCU repaired. I would guess it could be of approximately the same price, depending of what damage your CCU has of course. I would recommend to do the repair and can help you with that if you need so. Please do not get rid of your CCU, it is worth working on, these are getting scarce over the years.
The 993 A/C max button is really just a shortcut for functions that can be set manually on the CCU anyway, so you you really do not gain much in using a 993 CCU in your car.

Cheers,
Tore

Bob, I have a CCU, I tryed to use it on my 964 and it did not work so I fixed my. The one I have has two ac buttons. It is for sale, not sure what I can get for it. This one needs to be repaired, the clear part under the cover is broken.

Sorry the message is for ToreB not Bob.