AC compressor cycling rapidly for 30 seconds after start

I think I have a problem with my '95 850. I use the A/C quite a bit,
and it has been blowing cool/cold. For the last two days, whenever
I cold-start the car with the A/C on, I can hear the compressor/clutch
cycling once a second for about 30 seconds. Then it stops, and air
blows cold.

I took it in this morning to my Volvo mechanic, and he told me that
the system was charged. By the time I got there, even though I turned
the engine off, and then back on again, it had stopped happening so
I couldn't reproduce the problem over there.

Both times that it has happened, it has happened after the car was
parked overnight. Is this the first signs of evaporator failure?

About a week ago I added one 14 ounce can of R134a to the system,
because it seemed like it wasn't cooling as fast as it used to. But
only about half the can went in.

Thanks,
Beverly

 

by Bev A. Kupf dropped his wrench,
scratched his head and mumbled,

Disconnect the High side overpressure switch on the back of the
compressor. The Volvo replacement compressors don't have the switch nor
do they have a port for fitting one.

Bob