Mads

Hi

I just got my AC system charged with R134a. The system have been offline all the time i have owened the car.
I bougth a sanden compressor from Erik, and a condenser for another guy. New dryfilter from the local dealer.. The system is holding pressure, and everything works perfect if i shortcut the AC clutch..

My problem is:
The Clutch will not engage if i use the original wire.. If i disconnect the wire and test the voltage, it reads 10,8 volt... if i connect it to the compressor again it suddenly reads 0 volt.
What is going on ? is there not enough voltage to engage the AC clutch ? or do i have a defekt relay ?

Hope you guys can help me

Mads

BTW the car is a 1977 Euro 5 speed

Mark Anderson

Sounds like the relay in your a/c head.

SharkSkin

I just went through this. Thread here. Trace the circuit back until you figure out where the voltage is dropping. Do you have the current flow diagram? If not, I posted a big enough piece of the diagram on that thread that you should be able to troubleshoot further. If you're getting low voltage at J2 then it could be a problem with the control head or the freeze switch. If the voltage drop is between Q2 and the compressor it could be the low pressure switch. If you're getting low voltage at J1 then it could be fuse 17 or the blower relay. If the voltage is fine up till Q2 then you could have a bad speed relay. Or you could have PO-hacked wiring as I did. I'll have an update posted to my site in the next day or two, detailing how I corrected the problem.

HTH

okbarnett

if you apply 12 v to the clutch wire, does it activate the clutch?

Erik - Denmark

Mads,
Check the pressure sensor in the dryfilter
Regards from Erik in Denmark
Ps: I am happy to hear 'my Sanden' compressor is mounted and working well

Mads

It works perfect if i apply 12v to the Clutch...
Erik. How do i check the Pressure sensor ?
The relay clicks when i turn the AC on.. How can i check if there is something wrong with the relay ?

Mads

Mads

Somehow i didnt get daves reply i will check the voltage tomorrow...

Mads

SharkSkin

No prob. To clarify, I suggest you either work backward from the compressor(check Q2, J2, J1, fuse) or forward from the fuse (fuse, J1, J2, Q2)

SharkSkin

Update posted; see "AC Chillin" section of my site and/or the topic that I linked above.

Ed MD

Go to the Nichols site and look up DrBob's notes on the work-p, I just did it for my 88. I used the radio shack relay, works great Ed M

88 S4,
85S

SharkSkin

I'm pretty sure 78-9 had no relay in there, as the circuit works when the battery is disconnected. I could be wrong though... wouldn't be the first time

goliver

Dave et al,

The heads are supposed to be different on the early cars. They don't have the relay.

I thought I had the dreaded relay issue on my S4. Turned out to be that the PO unplugged the a/c button when installing the stereo. Good luck and hopefully you will be chillin soon. I sent Dr. Bob a pm with some questions when I was having my issue and he replied real quick with some excellent strategies. He is very knowlegable and is also a nice guy. If you get frustrated, drop him a line.

Regards,

Erik - Denmark

Mads,
The pressure sensor is a simple on/off switch securing that the compressor is not running if your cooling media is too low
So simply check the switchs, is it on or off - It shall be on (The 2 wires coming out of the switch)
Regards from Erik in Denmark