A/C issuses M126GX

[trooper632]

Hello, The issue i have is with my 2013 M126GX. The A/C blows cold for about the first 10 minutes then starts to blow warm when running at full throttle when plowing or running a hay cutter. If the throttle is set around 3/4 it stay blowing cold. The system is clean i always blow out the condensor in the engine compartment, clean all filters, and have replaced the evaporator under the seat, replaced the compressor and it is fully charged R134. Its been doing this before i replaced all new parts, but still no change. Im lost

 

[DustyRusty]

Blowing out the condenser and evaporator is not enough. They both need to be washed and there are special chemicals to do this efficiently without damaging the coil materials. The one that I use is made by Simple Green and it is available at Home Depot. Not all stores carry it, but you can order it online and have it sent to you or your local store. I buy the gallon size and put it into a spray bottle. Most likely your condenser and evaporator look clean but the air can't get through the fins until you clean them properly. As a result, the system is overheating and doesn't produce any cooling.

 

[Flintknapper]

Blowing out the condenser and evaporator is not enough. They both need to be washed and there are special chemicals to do this efficiently without damaging the coil materials. The one that I use is made by Simple Green and it is available at Home Depot. Not all stores carry it, but you can order it online and have it sent to you or your local store. I buy the gallon size and put it into a spray bottle. Most likely your condenser and evaporator look clean but the air can't get through the fins until you clean them properly. As a result, the system is overheating and doesn't produce any cooling.

Agree that both the condenser and evaporator probably still have chaff/debris in the fins. But even if they don't....they both will develop a 'film' of dirt/dust that if not chemically removed can impede the heat exchange they are designed to do.

The evaporator absorbs heat and transfers it to the refrigerant. The condenser expels that heat.

So....having clean components will always give best service. That said, the symptoms seem to point to under hood/bonnet heat soak which effects the ability of the condenser to expel heat as well as it could.

I would be curious to know the engine coolant temp at full load.

Another possible issue could be with the TXV/Orifice Tube.

 

[Lug66]

Have you verified that your heater isn’t leaking past the shutoff valve during high rpm? At that rpm your generating the most heat and the water pump is at maximum output.

 

[BAP]

Have you verified that your heater isn’t leaking past the shutoff valve during high rpm? At that rpm your generating the most heat and the water pump is at maximum output.

I second what Lug66 asked you. Heater valve leaking coolant by is one of the biggest causes of tractor AC to stop working after the tractor has been run for a while. The easiest way to check that out is to pinch off the coolant line coming off the block running to the cab. Permanent solution is to put a ball valve in the line and shut it off when you need the AC.

 

[trooper632]

Agree that both the condenser and evaporator probably still have chaff/debris in the fins. But even if they don't....they both will develop a 'film' of dirt/dust that if not chemically removed can impede the heat exchange they are designed to do.

The evaporator absorbs heat and transfers it to the refrigerant. The condenser expels that heat.

So....having clean components will always give best service. That said, the symptoms seem to point to under hood/bonnet heat soak which effects the ability of the condenser to expel heat as well as it could.

I would be curious to know the engine coolant temp at full load.

Another possible issue could be with the TXV/Orifice Tube.

Engine temp is in the normal range all the time

 

[trooper632]

I second what Lug66 asked you. Heater valve leaking coolant by is one of the biggest causes of tractor AC to stop working after the tractor has been run for a while. The easiest way to check that out is to pinch off the coolant line coming off the block running to the cab. Permanent solution is to put a ball valve in the line and shut it off when you need the AC.

I'll look for that line ant try to figure it out, thanks

 

[trooper632]

Blowing out the condenser and evaporator is not enough. They both need to be washed and there are special chemicals to do this efficiently without damaging the coil materials. The one that I use is made by Simple Green and it is available at Home Depot. Not all stores carry it, but you can order it online and have it sent to you or your local store. I buy the gallon size and put it into a spray bottle. Most likely your condenser and evaporator look clean but the air can't get through the fins until you clean them properly. As a result, the system is overheating and doesn't produce any cooling.

Ive got 3 kubota cabbed tractors but have never had to use chemicals on any of them, the other two blow fine but I'll try this first to see. They all get used for the same kind of work, thanks for the reply

 

[Flintknapper]

Engine temp is in the normal range all the time

Good. Then we can assume the fan is pulling/pushing enough air across the radiator and condenser to prevent 'heat soak' in the engine compartment.

I think the suggestion to look at the heater circuit (not fully closing) might indeed be where some or all of the trouble is.