2000 GMC Sierra AC System Help

[Derek Dewar]

(2000 GMC SIERRA 5.3 1st Design AC System) Truck is filled with refigerent and has high pressure reading of 150 and low pressure reading of 29-30. Everything except evaporator has been replaced but it was flushed. My problem is the truck cycles too often like every 20-30 second but blows ice cold. 

[dna9656]

Many do not know that the AC cycles to dry the air for the defroster, I have noticed the AC cycling when everything is off, the defrost, the heaters the AC and still it cycles; maybe, I thought it cycles to keep the seals  from drying out... who knows, as long as it's keeping me cool I 'm content.