85 SEC 126.044 AC Wiring Diagram Help
Thread Starter
Junior Member
Joined: Aug 2008
Posts: 19
Likes: 0
From: Lewistown, PA
1990 560SEL
85 SEC 126.044 AC Wiring Diagram Help
I have taken my 85 SEC out of storage and found the AC compressor wouldn't cycle. System pressure was good so I checked the sensors and found the low temp sensor was open. No surprise after such a brutal winter and I believe it may be original. So to prove out I shorted across to see if the compress would cycle on. No go! I then found I didn't have 12V at any of the sensor terminals. Fuses are good. I tried ringing out the lines in ACC83-85.pdf page '306' and started finding some wire color / function discrepancies. I do have 12V at the interior control head pin 12 on C2 and output at pin 6 on C1. Button changes on the control open and make the connection as expected. Therefore I was expecting 12V out at the sensors. Compressor coil is good and activates when I 'hot wire' it for testing.
There is a black/red and black/red with a green dot at the sensors. Neither of these have 12V as I expected (disconnected from sensor). There is a brown and a brown/blue wire for the other sensor. The brown wire is ground but I cant' see / find where the brown/blue wire goes. These colors are different than the diagram. Since the brown wire for the one sensor is ground, I assume this is a current path for a relay. However I can't find this path and I don't see a wiring diagram that is similar.
So, is there a 'correct' wiring diagram that applies to this car? Anybody seen this before? I'm not sure how to continue troubleshooting since I don't have confidence of the wiring diagram. Any tips / hints would be appreciated.
Nathan
There is a black/red and black/red with a green dot at the sensors. Neither of these have 12V as I expected (disconnected from sensor). There is a brown and a brown/blue wire for the other sensor. The brown wire is ground but I cant' see / find where the brown/blue wire goes. These colors are different than the diagram. Since the brown wire for the one sensor is ground, I assume this is a current path for a relay. However I can't find this path and I don't see a wiring diagram that is similar.
So, is there a 'correct' wiring diagram that applies to this car? Anybody seen this before? I'm not sure how to continue troubleshooting since I don't have confidence of the wiring diagram. Any tips / hints would be appreciated.
Nathan
Thread Starter
Junior Member
Joined: Aug 2008
Posts: 19
Likes: 0
From: Lewistown, PA
1990 560SEL
The car is USA as best of my knowledge. I do believe I figured it out. I was confused as to the temp switch for the fan control and confused this with the evap. core temp switch (which was open). I shorted across the evap temp switch and did get compressor activation. However I realized now I also now have a condenser fan issue.
