How to troubleshoot A/C electrical issues?
Thread Starter
Rennlist Member
Joined: Jun 2004
Posts: 2,355
Likes: 311
From: Vancouver WA (Southwestern) WA)
How to troubleshoot A/C electrical issues?
So, my A/C system quit working, no cold air, so I ran a Piwis diagnostics. Here is what I found:
1. Refrigerant pressure 2.4 bar, seems ok on low pressure side.
2. Compressor current 0A bad.
3. Compressor speed 0 RPM
so clearly, the compressor is not activated and may not getting the 100 hertz signal to engage.
I checked the two A/C fuses, which ohmed out fine. I am assuming since the ecu is reading the correct R134a pressure, it should enable the A/C relay?
Any advice in troubleshooting further? I know there are additional relays and fuses behind the rear seats, but I wasn’t able to find a schematic.
1. Refrigerant pressure 2.4 bar, seems ok on low pressure side.
2. Compressor current 0A bad.
3. Compressor speed 0 RPM
so clearly, the compressor is not activated and may not getting the 100 hertz signal to engage.
I checked the two A/C fuses, which ohmed out fine. I am assuming since the ecu is reading the correct R134a pressure, it should enable the A/C relay?
Any advice in troubleshooting further? I know there are additional relays and fuses behind the rear seats, but I wasn’t able to find a schematic.
Rennlist Member
Joined: Jun 2003
Posts: 618
Likes: 170
From: Boise, ID
Good Rennlist threads on your issues. I just googled Porsche 991 A/C not blowing cold. It sounds like any refrigerant leaking (Low Pressure) from condensers might disable your compressor. I would start with adding some refrigerant and topping it off. See if that makes any difference.
AC Stopped Working
Porsche 991 A/C issue
AC Stopped Working
Porsche 991 A/C issue
Last edited by SilverSFR; May 14, 2024 at 03:48 PM.
Thread Starter
Rennlist Member
Joined: Jun 2004
Posts: 2,355
Likes: 311
From: Vancouver WA (Southwestern) WA)
Thanks, I saw that. I can’t find what the low/high pressures should be. Would you happen to know what they should be? 2.4 bar readings I go seems a little low.
Rennlist Member
Joined: Jun 2003
Posts: 618
Likes: 170
From: Boise, ID
I googled: Porsche 991 a/c refrigerant capacity
From Hard Rider: Thanks hard rider
You - 2.4 bar = 34 PSI
HardRider - When charging you want 35-45 psi at around 85F ambient.
Rennlist thread Below
A/C charge
From Hard Rider: Thanks hard rider
You - 2.4 bar = 34 PSI
HardRider - When charging you want 35-45 psi at around 85F ambient.
Rennlist thread Below
A/C charge
Last edited by SilverSFR; May 14, 2024 at 05:18 PM.
