ok all here is the issue,
pulled the engine and everything out of the engine compartment, put everything back in, ran the car for about 6 months now that its starting to heat back up decided to recharge the a/c. the a/c was converted over to 134a and ran fine before pulling it out. but now I got good pressure on the low side, 1 and 1/3 bottle in and the compressor will not cycle, the receiver pressure sensor is closed the high pressure sensor is closed. haven't checked the compressor clutch relay yet (haven't found it), I have power going to the two sensors. now connecting a wire to the green wire on the clutch will engage it and the pressure will come down but I don't want to finish filling it that way either. any ideas and the location on the clutch relay would be helpful

 

never mind I found the connection I had missed

 

I'm having problems trying to find the clutch relay myself. Did you find it and if so where is it located? I have a 91 RS 305. My compressor will not kick in. Wanted to see if it will work before i charge it up. Its completely empty. I tried jumping the the low side pressure switch on the accumulator with a paper clip. Also I used a voltmeter to test the clutch connector,,,nothing. I had to directly jump the prongs on the compressor clutch to the battery, the clutch clicked but thats it. Any thoughts?

 

The compressor clutch will not kick on if your system is empty.

 

The relay is on the driver side on my '86 it might not be there on you '91, but there are two switches a hp and lp. The lp is on the low pressure side( closed with your system full) and the hp is on your high pressure side ( it makes sure the system is running right I believe it's normally closed) but both of these switches have to be closed for your system to engage the clutch