air conditioning failure

I own a New Holland T4.75 that i was using a week ago clipping pastures with a 7 ft Bush Hog. About 3 hours into a 4 hour activity I lost my air conditioning system. and finished the job with the doors open. I was running the tractor at rated 540 EPTO speeds at about 1600 engine rpm., As I finished the clipping and throttled back ..I proceeded toward the gate. After about 100 yards and as I approached the gate to the field .. the air conditioning system began to work again ???

This is what I know
site glass on the dryer is green... Refrigerant(134A) level is ok
Engine temp was normal
radiator/condenser and transmission cooler screen were clear of debris
Compressor belt is tight
Fan may not have been have been operating normally/ok.. at the time of the malfunction.. cannot swear to it. May have had too much beer to deaden the pain of "clipping" pastures.
I was clipping north to south with the afternoon (3 PM) sun beating agains the cab pillar that houses the fan switch and thermo0static controls.

Since that time ..the afternoon of 7/22... the air conditioning system has been operating ok/normally... using the T4.75 to cut and bale..along with some "chore" work.... no problems..

I called and sent an email outlining the problems to my New Holland dealer.. so far no feedback on what the problem may have been and may be "lurking" on another hot summer afternoon...I know that baling 75 round bales, yesterday afternoon, I was somewhat petrified that the air conditioning system may fail.. in the 90 degree heat.. thankfully it didn't..

I'm beginning to think I dreamed this whole episode up

..any ideas???

thanks
 
If the humidity was high, it could have frozen up.My service truck does the same thing every once in a while when temp is in the 90's and the humidity is high. If it does it again,turn the a/c off and the fan, wait 5-10 minutes and try it again. Give the evaporator a chance to defrost.
 
It's like Chinese water torture waiting for an air conditioner to quit. This spring I spent $1000 putting new air in an old tractor. It worked fine but I got tired of waiting for it to fail. After 40 years you just change things out whether they need it or not.

You are going to have to wait until it happens again and spring into action. See if the compressor is cycling. See if there is power to the compressor clutch. This is the farmer way of doing it. Or...

You take it in and spend $1500 so they can fiddle with it and possibly fix it. I think I would wait it out. I can't be without air anymore on these 100 degree days so I know how it would be. My bearings are getting worn enough that I can't keep my oil pressure up!
 
It is possible that it is slightly overcharged. If the low side pressure gets high enough the freon won't change to a gas in the evaporator or the same thing will happen if there isn't enough heat being removed from the condenser.
 
If like my John Deere they have a defrost switch at the evaporator and if it got to cold it stops the compressor. That is fine when it works. But mine the switch stuck open so the compressor didn't come back on . It acted just like yours until 1 day it didn't come back on at all and had to replace it .
 
If the evaporator freezes up, it means that it is getting TOO COLD. Not over or under charged. It means that the cycling switch is apparently not cutting out when it should.
Now, if the compressor operates continuously and the charge is a bit on the low side, it will bring the temperature of the evaporator too low and the condensation from the air will freeze on the evaporator instead of dripping off like it normally would. The main purposes of the cycling switch is to protect the system from freezing and to prevent operation if the charge is too low.
This is the most likely cause of the problem.
 
I'm betting it's an intermintent lose of 12 volts. I would carry a vom in the cab so that if it fail's again you can start at compressor clutch working back to switch to find where current stops.
 
(quoted from post at 13:55:03 07/29/16) I own a New Holland T4.75 that i was using a week ago clipping pastures with a 7 ft Bush Hog. About 3 hours into a 4 hour activity I lost my air conditioning system. and finished the job with the doors open. I was running the tractor at rated 540 EPTO speeds at about 1600 engine rpm., As I finished the clipping and throttled back ..I proceeded toward the gate. After about 100 yards and as I approached the gate to the field .. the air conditioning system began to work again ???

This is what I know
site glass on the dryer is green... Refrigerant(134A) level is ok
Engine temp was normal
radiator/condenser and transmission cooler screen were clear of debris
Compressor belt is tight
Fan may not have been have been operating normally/ok.. at the time of the malfunction.. cannot swear to it. May have had too much beer to deaden the pain of "clipping" pastures.
I was clipping north to south with the afternoon (3 PM) sun beating agains the cab pillar that houses the fan switch and thermo0static controls.

Since that time ..the afternoon of 7/22... the air conditioning system has been operating ok/normally... using the T4.75 to cut and bale..along with some "chore" work.... no problems..

I called and sent an email outlining the problems to my New Holland dealer.. so far no feedback on what the problem may have been and may be "lurking" on another hot summer afternoon...I know that baling 75 round bales, yesterday afternoon, I was somewhat petrified that the air conditioning system may fail.. in the 90 degree heat.. thankfully it didn't..

I'm beginning to think I dreamed this whole episode up

..any ideas???

thanks

What did you expect running it in economy mode????
 

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