I have a 2001 f150 lariat crew cab that after pulling a vacuum on the ac system and charging with 33 oz. of 134a, it still doesn’t cool. Compressor constantly turning on and off only staying engaged for only about 5 seconds at a time. Can anybody give me some ideas on what could be wrong?

 

Hi Tommy,
The better way to determine what might be wrong would be to have a set of gauges connected to the system to see just what is going on.

The symptoms are what you might see with a low refrigerant charge, but we have no way of knowing what is happening inside the system.
If you could see the pressures on the low side, it could confirm a low charge. Does the accumulator show any signs of cooling at all? Just feel the top of the reservoir and if it is starting to feel cool, it just might need some addl 134. I know you are 'wearing eye protection' when doing anything with A/C work , right !!!

 

Could be a partially plugged orifice causing high pressure making the high pressure switch trigger off and on. I show 33 oz. of R-134a as a full charge for your vehicle. Like Hanky said, a set of gauges would show you what's happening.