06 Sierra ac cycling issue

[FF259]

I have a 2006 GMC Sierra 1500 4x4. A/c has been out for over 2 years had a bad compressor never got around to fixing it. Today I replaced the compressor, condenser, accumulator, orifice tube, and flushed all lines. Took it up to my buddy at the dealership and we charged it up. Put it under vacuum for a bit and no leaks. Drove home about 12 miles no problems blew ice cold. Left to go to the store about 2 hours later started it up the ac button was on but clutch wasn’t engaged and ac blowing warm. Turned the button off then back on clutch engaged and blew ice cold. About 10-15 seconds clutch disengages blows hot cycle the button again blows cold again. Every 10 seconds or so it blows hot and I have to cycle the ac button on the dash again get cold air.

I know the compressor clutch should cycle on and off that’s normal but I don’t think it should be that frequent and you shouldn’t feel that significant of a temperature change right? And when it cycles off it doesn’t come back on unless you cycle the button. 
 

I’m thinking a issue with the low pressure switch on the accumulator but any advice? 

Edited August 6, 2020 by FF259
More info

[Jsdirt]

I can only guess from here.  Definitely test the low pressure cutoff switch. First thing I'd suspect is the HVAC controls in the cab, especially if it's automatic climate control, but I'd want to see what the pressures are doing when this happens. Could be overpressure due to a restriction, or air that got in during the recharge,

[diyer2]

I would jump the low pressure switch with a piece of wire. 

[FF259]

OK so I went out this morning and messed around with it some more. Started the truck turned the ac on. I let it sit and run for about 45 minutes no problem at all. Ac blew cold and compressor cycled on and off occasionally like it should. Problem happens anytime you accelerate or give throttle. Gave the truck a quick press of the throttle and clutch disengaged never came back on until I cycled the ac switch like stated earlier. Went and drove it problem happened continuously like earlier. Got back to the house sat in park didn’t touch throttle and no more problem. Basically anytime you press the throttle is disengages. Another thing I noticed is when you first crank the truck even though the AC button is on the clutch is not engaged and not blowing cold you have the cycle the button for it to start working. 

Btw this is automatic ac. 

Also when the problem happened and the clutch was disengaged I tried jumping the low pressure sensor it did not make the clutch re engage. 

It does seem like the control head in the cab would be the cause sucks because I’ve already replaced it once awhile back and it well out of warranty. 

Edited August 6, 2020 by FF259

[Jsdirt]

There could be a high pressure cutout tripping, due to excessive high side pressure, or a faulty sensor.

 

If it is the control unit, DO NOT use any Dorman product to replace it. Better off with junkyard parts than Dorman, just FYI.

[FF259]

3 minutes ago, Jsdirt said:

There could be a high pressure cutout tripping, due to excessive high side pressure, or a faulty sensor.

 

If it is the control unit, DO NOT use any Dorman product to replace it. Better off with junkyard parts than Dorman, just FYI.

Dorman is exactly what I used the first time its a POS. Most the lights on it are already out. Can you have the correct amount of Freon in the system but the high side pressure be to high due to the outside temp? Also would it make sense that if it was over charged when you give throttle that makes the pressure get even higher which would cause the high pressure switch to cut it off.
I know we put the correct amount in there (1.6lbs) but I’m wondering if maybe some air got in there causing some extra pressure. 

[Jsdirt]

Make sure the condenser, and the space between the condenser and radiator is clean of debris. Also make sure the fan clutch is good, if not electric.

[FF259]

1 hour ago, Jsdirt said:

Make sure the condenser, and the space between the condenser and radiator is clean of debris. Also make sure the fan clutch is good, if not electric.

It’s electric fans. How would I determine if the condenser or line is blocked 

[Jsdirt]

Usually you'll get a cold spot on a condenser that has a restriction. Since your system works occasionally, it's doubtful this is your problem. You need to see what the pressures are doing when it craps out and go from there. Could just be another failed control unit, or a failing clutch coil (or excessive clutch gap) if the pressures are fine.

[FF259]

10 minutes ago, Jsdirt said:

Usually you'll get a cold spot on a condenser that has a restriction. Since your system works occasionally, it's doubtful this is your problem. You need to see what the pressures are doing when it craps out and go from there. Could just be another failed control unit, or a failing clutch coil (or excessive clutch gap) if the pressures are fine.

Ok I won’t be back home till Sunday so I’ll put some gauges on it then