AC Problem Clutch Not Enguaging

Just pulled vacuum on system and recharged with 4 ibs of r134. right amount for 1999 tahoe with rear air. I have jumped out high and low pressure switches. Both had 12v present. If I jump out relay ac works fine, cools down to 50F. I also jumped out the cycle switch on compressor. I am not getting voltage to the ac clutch coil. What else could be keeping the clutch relay from engauging.

What engine?
How and where are you jumping relay?
The ac switch panel turns on computer to turn on ac clutch relay.
The computer turns on relay on the dark green/white wire to relay.
See if it is switching on and off there.there.
Also Relay has 2 fuses to it clutch and ign fuse.
Always check both sides of fuses for 12 volts.