ACEparts_com

Sorry, I mean the interior heater blower motor. I really only need the fan blades as I destroyed them during removal - I managed to fix the motor.

Ref the AIRCON relay issue - it's not the relay. Even with the controller removed from the dash I have 12v on one side of the relay coil and (with relay removed) 6v on the other. When the engine is started that quickly drops to ground thus energising the relay :O(

I've looked at the switch on the pipe up the front and don't see any orange/white wires there. To make this MORE frustrating I have access to the car for about 1 week in 12!

helmet155

the 3 pressure switch may be yellow/red there iirc.

ACEparts_com

Well i've just ordered a scantool to hopefully help diagnose the issue. Could be money well spent seeing as my airbag light is on too. Annoying thing is I spent 6 years as an autoelectrician and solved some extremely difficult problems on other peoples cars - usually in under an hour!

helmet155

Looking back on this thread, I think Tore may have hit it from the get go.

You haven't commented on the 3 pressure switch, it surely could be bad.

The 993 doesn't command clutch on for a/c until prox 10 seconds after the ccu switches are set also i think

ACEparts_com

OK, even with the 3 pressure switch disconnected (the one on the pipe above heater unit in bulkhead) the results are the same. This is also true for having the CCU disconnected at the same time. My assumption is that wherever the orange/white wire goes to (N143) is the cause of my woes!
If anyone has access to the wiring and can tell me what/where N143 is there would be a drink in it for them!
Thanks
Alan

ACEparts_com

If would appear to me that the actual signal to the AC relay doesn't come from the CCU (if life was simple!). There's not even an orange/white wire going to the CCU :0S

I have a red/white wire going to one side of the relay coil that goes live with the ignition and this darn orange/white to the other that goes to ground a short time after the alternator light goes out.

helmet155

I told you where the N143 goes before, and even the page numbers from the cannell.uk manual.

You can also download the 964 manual, the a/c system is similar (except for the mixing flaps iirc)

ACEparts_com

Yes, sorry, hard to keep updated here as i'm constantly on the move! I'm trying to locate M143 now! I actually feel as though I'm making progress - thanks :O)

Ref N143 - why on earth would the AC relay need to be connected to the clocks at the same point as the catalyzer relay?!?! What purpose could that ever be? Unless I have a clock issue then M143 must be the source of my problems but where the hell is it!?!?!?!?!?!?!

c993k

I thought you might be interested in reading this web page:
https://rennlist.com/forums/showthre...ferrerid=35662

Chris,
c993k

ACEparts_com

Thanks Chris; it's not that. M143 is my problem I think - it's location and function!

ACEparts_com

Or maybe someone can tell me how to decode where to find the matching connections? I can't find any references to them in the 993 wiring guide. Thanks in advance!

helmet155

N143 or M143?

ACEparts_com

I've traced N143 (well, you have) to the clock area. M143 is a connection between the relay and the pressure switch.

Thanks in advance!

ACEparts_com

I can simplify my problem - there's no wiring on the diagram at grid references M or N 143

guards red

Alan,

I'd be inclined to start at the compressor. Pull the supply relay, then pull off the connector on the compressor. As I understand it the relay provides an earth to the compressor which engages the clutch on the compressor. With the connector off, ignition off, see if the brown wire in the connector is earthed. If it's permanently earthed you have a short in the wiring. I would guess near the compressor. Look for cuts etc there.

Good luck.