2010 GMC Sierra cycling strange pressure readings

[Corvette95]

I thought I had a blend door issue and still might but my compressor is cycling. Pressure on low side will go to around 90 and compressor shuts off, high side will go to 250 and shut off and go back down to 125. I evacuated and pulled a vacuum overnight on my truck. It will take a little over a pound and the pressures stay around 40 and 150 but air blows at about 70 degrees . Outside temp is 84 and 65 humidity. I had an air blower on the condenser. When I add more Freon , still below required four pounds, it will again low side to 90 and high side to 275 and cycle and repeat. I put in a new orifice tube yesterday . I did add oil to it. Should I add oil again when I get some reposes here. I cannot figure this out .

[Tim]

Sure you put the orifice tune in the correct direction?

[GM Tech]

4 lbs????? sounds like an old suburban dual air----A sierra should be at about 2 lbs-- if no rear evaporator/single system- where is OT? in condenser outlet? or inline in front of evaporator