air conditioning problem

[tazewell]

I have a T5040. The air works great when first started for about 1 to 1-1/2 hr. After that amount of time the output becomes less and less. The air that is coming out is still very cold; just not much coming out of vents. I appreciate any help.

 

[pjbci]

The evaporator is partially stopped up with dust and the air flow over the fins is somewhat restricted allowing ice to build up and completely stop up your air flow. Ive had this happen many times on many machines. It can be a pain to get to the evaporator but you got to get it washed out with a hose.

 

[banjodunn]

G'day check your drain tubes too they can get blocked and stop the water from getting away allowing it to freeze.



Jon

 

[tazewell]

The drain tubes were the problem. Thanks for your insight.

 

[banjodunn]

G'day glad you found the fault we had a run on blocked tubes last year due to wasp nests being built in the tubes.



Jon

 

[Gator6x4]

I have a T5040. The air works great when first started for about 1 to 1-1/2 hr. After that amount of time the output becomes less and less. The air that is coming out is still very cold; just not much coming out of vents. I appreciate any help.

What you described is a classic example of "Evaporator Icing". The unit is low on refrigerant and the evaporator is icing over restricting air flow through it. Talk to a qualified AC Service person about topping off the refrigerant charge. Or if your are familiar with AC repairs hook up the gauges, obtain the high and low readings and determine how far out of specs it is.

 

[tazewell]

Banjodunn, I thought the drain tubes were the problem. They weren't. I cleared them with air and the problem still persists. We added more refrigerant bring the pressure up to 20. I think the low pressure is 10 to 30, so we should be in the range. However it still stops working after 1-1/2 hrs. The refrigerant might have helped as it used to stop after 1 hour. Any more ideas?

 

[pjbci]

Wash or blow the evaporator out.

 

[tazewell]

Wash or blow the evaporator out.

I have done both.

 

[tazewell]

I have washed & blown air through the evaporator. I took it to an local mechanic for system check tomorrow.

 

[pjbci]

Only other thing i can think of is we had a 1486 ih that would freeze up even with a clean evaporator unless we ran the blower on high all the time.

 

[r8nger]

If it has a small tube going into the evaporater, your system has a temp control switch and it probably has failed . This turns off your compressor momentarily so the evaporater doesn't freeze up.you can turn it off manually for a minute every couple minutes, and if it continues to blow cold then, you've found your problem.

 

[r8nger]

I re-read your initial post, you could also have a blower fan motor beginning to fail also, slowing down when it gets hot and not moving air. Hard to tell without being there

 

[tazewell]

I re-read your initial post, you could also have a blower fan motor beginning to fail also, slowing down when it gets hot and not moving air. Hard to tell without being there

I have reassessed the problem. It does not appear to be a problem with the fan.

 

[Utah Bison]

With gauges hooked up on both high (discharge) service and the low (suction port) measure the pressure during failure. Could be as stated thermal or pressure cycling switch failure. Or high pressure shut off due to low air flow through the condencer. If the the radiator is plugged with dust can cause excessive high pressure and shut down the A/C.
Some other thoughts.

Lee

 

[banjodunn]

G'day low pressure should be approx. 10% of high or lower I would aim for a high pressure reading of 175-185psi on a 25c day on the high side this pressure can be used with R134a and Hychill ( Hydrocarbon based gas) I'm sorry but I can't remember if this is the same as R12 but I think it maybe a little high


Jon

 

[tazewell]

Thanks to everyone who responded. The problem was low refrigerant.

 

[greavesytractor]

Ever since the start new holland cab tractors have been notorious for bad air cons iv had an L65 and L85 and they were shockers for the air con I know many contractors with these problems with the new ones as well!!

 

[tazewell]

Finally had time to take tractor back to dealer. Problem was thermostat. Repaired under warranty.

 

[DPD293]

I have a massey 383. Installed new compressor, new condensor at radiator, new high speed fan, blew out lines, new cab filter, cleaned cab condensor coils, washed them and blew them out, new freon, etc. First 2-3 used it froze my rear off. It runs cool for an hour or so then gets tepid inside cab. Add a can of freon and it gets cooler but not much. Checked for leaks. Any ideas???