JD 4055 ac problem

[Sherbert]

Additional info: system runs flawlessly for
1-1 1/2hrs, then compessor will run for 2min, disengage for 6min and repeat this cycle. Have tried:cleaned all screens,filters,radiator, oil cooler,evaporator/heater core; replaced dryer and thermostat; evacuated system; flushed system; pulled vacumn(held)no leaks indicated; recharged system with 4lbs 134a and oil; high and low pressures good; repositioned thermostat sensor in evaporator/heater core. No change.

 

[rexhellwig]

Flush the old mineral oil out before putting in R134A. The two combine to make a substance like chewing gum.

This needs to be flushed with special equipment - just blowing through the hoses with an air gun won't do it.

Forget adding the magic "ester oil" . A can or two of that parts store "flush" won't get it done, either.

Figure on installing an expansion valve calibrated for R134A while you have everything apart.

 

[rexhellwig]

And lets assume the heater valve isn't leaking and the radiator and condenser aren't plugged solid like most of the hay tractors around here are.

 

[Sherbert]

Thank you. But system was flushed with a flushing additive, not just air. Tractor was converted from R12 to R134A years ago including the expansion valve and ac has worked for a number of years, until last year.

 

[ryan3020]

What's the ambient air temp there? Have u put gauges on when while a/c acts up? If not check your hi and low pressure if u have what are they?

 

[tim s]

My guess Rex that is "exactly" the problem...works good till it can't breath anymore, the evaporator is freezing over from lack of air flow or/and the condenser is plugged and sending the high side up till it kicks off.

 

[Sherbert]

Thank you. When the compressor engages, cooling is more than adequate but it just doesn't stay engaged. Pressures have not been checked under these conditions.

 

[Sherbert]

Flushed everything and the system has good flow.

 

[rexhellwig]

Hard to say without being there.

 

[tim s]

I'm thinking the "inside" is okay,,out-side conditions can shoot a good AC in the foot...and maybe the high pressure switch is a bit weak, shutting you down after a bit of use.

 

[Brent R Weaver]

Check the thermostatic switch or temperature switch which ever you would like to call it. Check wiring connections under cab behind right battery box, also are fan motors quitting when compressor shuts off, if so check breaker in dash leftside of tractor. Would like to know pressures when it shuts down. Thanks, Brent

 

[Bob]

How about the circuit breaker for the clutch? I'm REALLY surprised no one mention that!

Could be a bad breaker, a poor connection at the breaker, or a failing clutch coil that draws too much current or shorts out after current flows through it for a length of time.

 

[Sherbert]

Thermostat new, fan direct drive, Thanks though

 

[jared in wi]

check your power supply

 

[Lee B]

In your power supply to the clutch there is a circuit breaker that has been placed in a place that takes 1 1/2 hours to get too hot and it is tripping needlessly. Move it to a cooler spot.

We had an old White tractor that did this and the only way we could run in the summer with the air conditioning on was to remove the left side engine cover panel and leave it in the weeds by the edge of the feild.