924Board.org

[MOTANUL]

I have a Porsche 924 turbo 2.0 S1 (1979-1980) with air conditioning. It was working fine for 8 years, but when I took the car out this year, it stopped working at all (you can't hear the nippondenso compressor engaging, the dedicated fan doesn't turn on, and the fan in front of the engine doesn't turn on either). As expected, I no longer have 12V on any cable that goes into AC SWITCH. The problem is that on all the diagrams I found the color codes don't match. On my car enter the following electrical cables in AC SWITCH:
4x
blue-black
blue-white
blue-yellow
brown
2x
yellow-green
yellow-black
No fuse is blown. Where should I start looking? There were times when nothing worked and then after a while everything worked perfectly.


_________________
1980 Porsche 924 Turbo (931) diamond silver metallic/helios blue metallic
sold Porsche 924 NA 1979

[924RACR]

Yeah, looks like a different diagram for the '79 Nippondenso system. Snagged a photo of that page in the manual, will upload and link...

Edit: hopefully this works...

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[924RACR]

So there's a few fuses to check... but quite obviously step 1 would be to look at the relay, since power comes through that, and if it's not switching any more (common problem for 944 AC systems, at least) obviously that'd be an issue.

The other easy/obvious thing to check would be to confirm the low pressure switch is OK... though that isn't so much aligned with your symptom of no !2V power at either of the switches. Clearly the blue/white wire on the 4-pin switch should have power with ignition on...

Another easy check of relay function is that simply turning on the AC blower fan switch should switch on both rad fans, with or without any temp in the rad... that would trigger both AC relays...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[MOTANUL]

I did exactly what you wrote. Thank you very much.
I checked both fuses and they were ok. Then I checked the AC relay and no current passes through it at all. There is a sense diode in it and unfortunately for me it no longer lets the current pass in either direction. Long story short, I need a new relay. Finally, I found the correct diagram for the AC wiring. My car is from 1980 - the diagram is for a 1982 car but everything matches.


_________________
1980 Porsche 924 Turbo (931) diamond silver metallic/helios blue metallic
sold Porsche 924 NA 1979

[morghen]

Check if you have refrigerating agent and pressure in the system.
I cant remember how the system works now but i think if you dont have sufficient pressure, the system wont even try to start.
_________________
Supercharger and EFI kits
https://www.the924.com