A/C clutch issues

SkyVolvo · Post by **SkyVolvo** » 26 Jun 2012, 15:45

Hey - I've got a '91 740 NA with about 185k on it, and the AC works off and on. When it's working, it's wonderfully cold and refreshing. When it's not working, it just blows hot air at me. Sometimes it will start working while I'm driving; sometimes it will stop working while I'm driving. Or I'll drive to one location and it works fine, only to get back in the car and have it not work. That sort of thing. It's been doing this for at least 3 summers now.

From my searches, I've been led to believe this is an A/C clutch issue - possibly a clutch that needs to be shimmed? What I can't find is anything related to 740s on this - I keep swimming through info on S60s, 850s, etc. - completely different animals. Does anyone know where I can find more info on this for my model? I'd like to be able to address the issue myself, but I've never worked on this system in a car before, and I'm starting from ground zero.

Many thanks.

Post by **jimmy57** » 26 Jun 2012, 16:23

Clutch issues can affect 740/940 models too. Your symptoms don't fit clutch gap problems though.
There is another thing that can make for random operation of compressor on 740/940 91-95.
The compressor relay is integrated with the control panel on dash. The solder connections and a circuit element on the PC board in the control are problems.
The solder joint is easy to fix if you can solder.
The face trim has to be pried around edges to get it off and then remove screws. Pull out part way and unplug electrical connectors and the vacuum connector.
The black plastic cover has to be removed and the circuit board screws removed. The relay is the black cube on the board and if you look on underside you should see the issue.