Stuck expansion valve. Dirty evaporator core. Blower fan intake dirty. Just a few possibilities. Now that it's potentially overcharged, the compressor could be failing and if that's the case, it can very easily spread pieces of compressor throughout the entire system and if that's the case, the entire systems components would need to be replaced. There's no good/reliable way to get the junk out once it happens. Some guys call it black death.
If in fact you had to add refrigerant earlier this year, I'd question why. If it was empty there is/was a leak. Why was it leaking? Where? Was it repaired? How long was the system at zero pressure, zero refrigerant? If very long, air could have gotten into the system, and air has moisture in it, and moisture will destroy parts. Also if there was a leak, it's not just refrigerant that leaks out, it's also oil and then the oil "level" is lower than specified, which can destroy the compressor. Sometimes the compressor will run a while, then seize up due to lack of oil and/or moisture, then it cools and it will "free up".
The tractor has had a small leak for a while. It has been known to freeze up after a couple months of use. When I pulled a vacuum and refilled the Freon I added dye hoping to find the leak. Since I did not know exactly how much charge there was, I evacuated the system, pulled a vacuum and recharged. I went by the sticker on the side of the engine on the charge amount. Two cans is the prescribed amount. I did Not add any oil when doing this.
Also this spring I removed the roof and thoroughly cleaned the evaporator and also the condenser using plastic strapping, coil cleaner, and copious amounts of water and air. The evaporator and housing was very clean to begin with.
I also added a condenser fan that made quite a bit of difference, especially when the tractor is not moving.
No one answered the question as to whether there is a high pressure switch and I cannot find one to order nor on the Kubota parts diagram so I am assuming this is a no.
I would appreciate the your opinion on this plan. I am in between cuttings and have time to properly check things out. I feel, as you said, this is a self inflicted failure. I have ordered an aftermarket compressor, exp. valve, dryer, and condenser.
These four parts were less than $700. Just the compressor from Kubota would have been over $1,500 (total would have been > $3,500). I do not have a way to buy Denso parts from a source like AP air.
I did NOT order an evaporator. I was planning to flush it and the lines since that is all that would be left. I was told it is nearly impossible to flush a Kubota condenser. Do you think flushing the evaporator until clear should be OK?
There are a lot of post about how undersized the condensers are on the M9000 but I do not see a way to mount the new style condenser. Have you heard of anyone doing this or something similar?
