I had to fire up my 1991 C4 with the climate control panel removed. Does the climate control set fault codes?

Thanks,

Bill

 

Yes it does Bill but it will reset itself again. It has already because power is removed totally from it. When you install it make sure your battery is disconnected. The unit is hard wired to the battery.
One little tip for all. When a Bosch hammer is hooked up the operator has to reset the DME fault codes first before accessing the HVAC.
Ciao,
Adrian
911C4

 

I know Adrian is very much an expert on the 964, so I will say to trust what he says, but will only post my experience with the HVAC here now because this just happened to me in the past week, and maybe this helps you:

My fan motor was staying on all the time in the HVAC unit. I took the car to a Porsche dealer to have it checked out. They tried to find the problem by plugging in a 993 hvac unit, but that didn't work. They e-mailed Porsche (the factory), and I picked up the car while we waited for the answer becasue of a coming snow storm. I drove the car with no HVAC unit in, and no fault lights came on (by the way, I have a 1993 964).

The dealer called me back and said a 993 unit won't work with my car, I need a 964 unit (or the updated 964 unit which has a part number that starts with "993"). Anyway, they put my broken unit back in, and I took the car back because I didn't want to pay the $1,300 for a new unit + $500 to install they wanted to charge me.

I pulled fuse #1 since I didn't want that small fan running all the time and draining my battery. I then bought a refurbished or more probably simply used HVAC unit from a Porsche dismantler for $350. My mechanic loaned me the tools to remove the old unit (basically two metal wires that fit in the left two holes and right two holes of the HVAC unit).

I pulled it out, unplugged it, and plugged in the new unit (pain in the neck, but whole job took me about 45 mintues). I then replaced Fuse #1, and checked the HVAC unit operation. Everything worked, and no lights on the dash ever came on during this process. The only thing I noticed was when I fist plugged in the HVAC unit and re-installed fuse #1, the fan by the driver's side (on the US car) front fender/tire that operates with the air conditioner turned on and off and on and off for maybe 30 seconds. I assume that was some sort of a diagonostic check or something.

Anyway, in my experience the whole unit can be removed and replaced, or the car can be driven with the unit disabled or fuse #1 pulled with no dash lights, although I don't know about any fault codes that might be in the system- everything seems to work find though. This may be because my car is later, or because I simply got lucky. Once again, I defer to the real expert (Adrian) for technical issues with this unit, but just wanted to relay my experience with you.

Good luck!
Andrew

 

Dear Andrew,
You are sort of going off at a tangent. The HVAC cannot bring any warn lights because it does not have any to bring on. The fault codes are stored in the unit and have to accessed using a Bosch hammer. If they are not cleared they remain there.
The story you relate about the control unit is well known and stored in the archives. What you have been told is quite correct. Lots of spare 993 control units being held by 964 owners. You need the 1991 and up control unit. The 89 and 90 unit will not work either because the wiring is changed.
If you look at your HVAC you need the same number except with 993 instead of 964.
Summary:
There are no warn lights associated with the HVAC. That is why you did not get any.
1996 and up 993 units do not work in a 964 of any version. I am not sure what was installed in the USA 1995 models of 993.
Ciao,
Adrian
911C4

 

Sorry that was a long post Adrian. I have a question then- if I have stored fault codes what does that do? Does it matter if my unit is fully functioning? I didn't reset anything with a Bosch Hammer....

Andrew