2013 Ford E-350 with 131k miles. Driving to our friend's house to load up to 200 chickens for processing, our ac started getting intermittent in 95deg weather. The ac hadn't acted up before so this was odd and disconcerting. What would cause the AC to just turn off and on? I took it to one shop and they said the AC was fine and they did a leak test on the system. A friend told me to check the compressor clutch spacing. What do you all think?

 

You say "the AC to just turn off and on". Does this mean the compressor is off and on while the blower, etc. continue to run normally?

If so, you may want to temporarily run wires from the compressor clutch connector to a lamp hanging inside the vehicle and see if the light goes out when the A/C stops. That will tell whether the clutch is disengaging with power still supplied or if the power to the clutch is turning off.

Here's the clutch circuit wiring diagram:

 

Without looking at the system, sounds like the system is low on refrigerant.

All we do in a case like this is , connect the manifold gauges and see what the pressures are.

If no one has done any kind of work on the system, that would be my first suspicion. Not hard to correct.

 

I agree with low refrigerant but the OP said "shop said the AC was fine" and "friend told me to check the compressor clutch spacing".

I was just suggesting a test to see which one is wrong. :-)

 

The clutch spacing is a remote possibility that would require special tools to correct.
The AC system when working properly will cycle on and off normally when refrigerant charge is normal.

The less refrigerant in the system the more it will cycle because the compressor is pulling down the pressure as required , but if charge is insufficient, the low press sw will open to protect the compressor..
If gauges are not available, we purge the line before connecting to the low side and then begin adding refrigerant GAS only.
You can tell with the system set on high max cold ,blower on high, if the system is getting near the amount required by feeling the accumulator. It will be getting very cold.
You stop adding there, if you don't have gauges to watch for correct pressures.
New vehicle systems do not require as much refrigerant as compared to older vehicle systems and can be easily overcharged.
Safety is always first, and eye protection is a must !