Ac Goes On And Off

[tbs]

I have a 1999 Chevy Silverado with a 5.3L engine with 150,000 miles on it. After the engine has been running a while, the AC kicks off. The fan / blower is still working, and the AC light is on next to the AC button on the dashboard, but there is no cold air. I can turn off the AC switch on the dash and wait about 30 seconds and turn it back on and I have ice cold air blowing out. It will work for 5 to 10 minutes, then it goes out again.

 

I have checked the coolant / refrigerant lever and it is ok. I have also replaced the low pressure sensor switch on the evaporator core. I was about to replace the high pressure sensor switch, but wondered if anyone had any suggestions. The switches are about $15 each, so it is not bad but the try and replace method can add up after a while. Anyone else had this happen, any thoughts.

 

Thanks

[ChevyTech007]

Sounds like a bad fan clutch. Turn the fan by hand back and forth a few times and see if it becomes very easy to turn. If it does you need a fan clutch.

[bobcat5544]

I've never seen a fan clutch cause that problem, but most likely causes would (list starts with most likely)

 

Compressor clutch relay

Ac control head

Restriction in ac system causeing the high pressure switch to cut off the ac.

[ChevyTech007]

Restriction in ac system causeing the high pressure switch to cut off the ac.

 

Not trying to be a jerk, but would a worn out fan clutch not cause this?

Wish I had a dollar for every on I have changed, oh, wait a minute, I do. :-)

[bobcat5544]

The reason why I don’t believe it to be a fan worn out fan clutch is there is no complaint of the truck over heating, and usually the complaint would also state ac gets warm when at stops or when idling but is cold while truck is moving.

 

That is why I lean more to the ac compressor relay or the control head.

[ChevyTech007]

Any update on this one???