My Suburban's AC comp clutch  cycles on and off in 5 sec intervals at least 10 times.  Around the tenth cycle the compressor will not engage at all.  The digital climate control will then flash "AC" over and over.  I disconnected and reconnected the battery and it did the same thing.  I then disconnected the switch on the Dryer Accumulator and jumped the harness.  When I did that the compressor and AC system functioned normally.  There is one of two things going on...either the switch is bad or I am low on refrigerant.  In event it is the refrigerant, can R12 be mixed with Freeze 12?