Greetings everyone;

The AC clutch on my Volvo 93 with 12000 miles does not get engaged which it would not allow me to re-charge the system. I would appreciate for any tips you may have.

Best Regards,
Habib

I'd try checking the wire running to the compressor for voltage first. With the car on / engine not running / A/C turned on, see if you get 12V at that wire. If you do the problem lies with the compressor/clutch, if you don't the problem may be with a relay or some other component.

I would recommend doing this first because if you start jumping switches you may end up frustrating yourself if in the end the problem was with the compressor because good components may end up appearing faulty.

Hi,

Your car with only 12000 miles is it correct? If it is then your AC system may be under-utilised. Over the years the refrigerant could seep out of the rubber hoses and seals.

Next question is about which is better, refilling (top it up) or vacuum it down to find the leak. That also depends on the condition of the rubber parts which is a hard thing to tell over the internet. I guess by refilling it straight-away you could depend on luck hoping it would hold.

After refilling apply soapy water around the joints and rubber hoses to find any leak.

Regards,
Amarin.

Amarin,

Thank you very much for your time. In response to your question, The AC was working nicely until a couple of weeks ago. The clutch does not engage now which would not allow for the compressor to function. I have checked the 30 amp fuse and its fine. I am wondering if there is a relay for the 93 940 AC? I have looked all over the internet for the related relay; however I have not been able to trace it. I tried to re-charge the system but it could not be done without the compressor working. Again, thank you!

Best Regards,
Habib

Hi,

The AC relay is located INSIDE the AC control unit on the central dashboard where the blower switch, temp control and air vent selectors are located.

The relay itself is soldered onto a circuit board inside the unit. Usually the relay is ok but its solder connections are not. Cracked solder joints underneath the circuit board is a common known fault. Re-soldering these usually restores the AC function.

Refer to the FAQ on AC control unit:
https://www.brickboard.com/FAQ/700-900/HeatingAirConditioning.htm#AccesstoClimateControlUnit

Before you go on dismantle the AC control unit looking for faulty solder joints, try to jump the low pressure switch electrical connector as Tedv has suggested. With engine running, blower running and AC set to ON, short the connector's inside terminals using paper clip or wire.


Photo of pressure switch connector (circled red):


By jumping the above connector your compressor's clutch should engage if your AC control unit has no issue (also means the AC relay and solder joints are ok). You could then refill as usual. If jumping doesn't produce any result then you could go on dismantle and re-solder the unit via the FAQ.

Regards,
Amarin.

Have you made sure that there is no leak in the system?
If so, (otherwise the charge is pointless), you have to disconnect the pressure switch on the receiver/dryer and jumper the plug to get the compressor to engage and turn on and suck up the new gas. That's of course assumes that the compressor is good.