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The wiring colours can vary between the 964 an 993 models, I guess this is the cause for the confusion. You have to check if the active-GND signal comes from the ccu, and if it is interrupted by the pressure switch. You also have to check if the evaporator sensor is ok, If not, the CCU will not engage the compressor.
This is easiest done by checking for OBD fault codes in the ccu, or by testing the sensor value with an ohmmeter on the ccu harness connector.
Cheers,
Tore
Apologies about the slow update on this. I ended up swapping out the evaporator, diverter valve, and drier to ensure there were no leaks in the system.
As a result of 30 years of salt roads my fuel lines corroded to nothing when I went to pull the tank so I also built some PTFE/braided fuel lines using AN fittings.
The good is that there are no fuel leaks and the car didn't catch on fire!
The bad is that I added 24 oz. of r134a coolant, which made the pressure in the system jump to ~50psi on the coolant can gauge, so I checked the pressures with my manifold gauges and the low was ~40PSI and the high was ~350.
I had the compressor jumpered so it was engaged and running. Still no cool air and now I am at a complete loss.
The A/C fan in the wheel well turned on after about the first 12 oz. of coolant was added.
Logically thinking, I know there's coolant in the system, I know it's holding pressure without leaks, I know the compressor is functioning, the last thing I can think of is a wonky CCU...
By the time I get this figured out it'll be winter and I won't need A/C anymore!
On another note, I found this little connector sitting on the top of my FPR.
Anyone have an inclination as to what it's for? I didn't see a very obvious place on the intake anywhere.
I’m no 964 HVAC expert, but from the data I’ve read it seems your low and high sides are too high.
Have the mixing chamber and evaporator sensors been cleaned?
Not that I'm aware of, so I would hazard a guess that they haven't been cleaned in nearly 20 years.
I'll have to do some research on location/DIY.
Since most of the focus has been on the running gear I'm getting to the point where all of the ancillary items need to be addressed so it's very much a learn as you go thing...
I do not agree. As mentioned above, you have to check if the active-GND signal comes from the ccu, and if it is interrupted by the pressure switch. You also have to check if the evaporator sensor is ok, If not, the CCU will not engage the compressor.
This is easiest done by checking for OBD fault codes in the ccu, or by testing the sensor value with an ohmmeter on the ccu harness connector.
You also have to check the +12V feed for the A/C compressor relay, it gets feed from the front fog relay. See details on my DIY website.
Cheers,
Tore
07-20-2019, 09:38 AM
