I have a L4330 tractor with hydrostat transmission and a enclosed cab. The tractor has 930 hours. The a/c is not cooling properly so I cleaned the front of the radiator and the a/c radiator. I replaced the power relay located in the roof, the A/C controls located in the cab, installed a new a/c compressor and accumulator, blew out the lines as best that I could, filled the compressor with oil, then added 2 cans of freon. The fans blow ok, the compressor is working but the air coming into the cab is still not cold. Any suggestions would be helpful....Thanks
A/C not cold in L4330
- Thread starter DMcIntosh
- Start date
BAP
Well-known member
Lifetime Member
Equipment
2012 Kubota 2920, 60MMM, FEL, BH65 48" Bush Hog, 60"Backblade, B2782B Snowblower
Did you put a vacuum pump on the lines to suck out all the air before adding refrigerant? If not, that is probably your problem. You need to remove all the air by putting a vacuum on the whole system before adding the refrigerant. Was there a reason you replaced most of the parts? Did you replace the drier?
CountryBumkin
New member
Lifetime Member
Equipment
BX2370 w/LA243, Bucket, Grapple, QA Pallet Forks, 60" MMM, rear blade & rake
As mentioned, the correct procedure when replacing the compressor after a failure is to flush the condenser and evaporator with "cleaning solvent" not just air.
Then you add a specific amount of oil to the condenser, evaporator, and accumulator/drier (not just all in compressor) so that way the compressor is not overcharged with oil when first starting, or the compressor does not end up low on oil after the oil has circulated and the other components have retained some of the oil.
You must pull a vacuum on the system. That is what removes the air and moisture form the system. Then you add the specific amount of charge as specified in the manual (but you can usually get away with adding refrigerant based on the gauge reading and ambient air temp.
I'm not familiar with the AC system used by Kubota, but if your system uses an orifice tube rather than an expansion valve, you want to be sure to have replaced that as well.
Then you add a specific amount of oil to the condenser, evaporator, and accumulator/drier (not just all in compressor) so that way the compressor is not overcharged with oil when first starting, or the compressor does not end up low on oil after the oil has circulated and the other components have retained some of the oil.
You must pull a vacuum on the system. That is what removes the air and moisture form the system. Then you add the specific amount of charge as specified in the manual (but you can usually get away with adding refrigerant based on the gauge reading and ambient air temp.
I'm not familiar with the AC system used by Kubota, but if your system uses an orifice tube rather than an expansion valve, you want to be sure to have replaced that as well.
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Everyone has good points.
Clean the exterior of the evaporator coil and the condenser coil.
Remove the expansion valve/ orifice tube, Flush the system to remove all contaminates, replace expansion valve / orifice tube,
Replace the dryer when replacing any parts.
Find out the specific requirements for your system, Via WSM, amount of oil and amount of Freon.
Add oil to compressor and accumulator.
Pull a vacuum on the system for 1 hour to remove air, but more importantly remove moisture (vacuum boils the moisture out).
Charge to specified amounts and use gauges to do so.
Clean the exterior of the evaporator coil and the condenser coil.
Remove the expansion valve/ orifice tube, Flush the system to remove all contaminates, replace expansion valve / orifice tube,
Replace the dryer when replacing any parts.
Find out the specific requirements for your system, Via WSM, amount of oil and amount of Freon.
Add oil to compressor and accumulator.
Pull a vacuum on the system for 1 hour to remove air, but more importantly remove moisture (vacuum boils the moisture out).
Charge to specified amounts and use gauges to do so.
Last edited:
Was the system vacuumed? If so, what micron, or what in/hg? What is the outside temp? What is the humidity?
Is the belt slipping?
Why was the compressor replaced? They typically don't fail UNLESS the system is neglected...e.g-let the condenser get totally plugged and continuing operation for a long period of time. IIRC the compressor is a scroll type compressor-excellent design, very few moving parts, small, and tough. But not indestructible. Also expensive.
Have you checked the evaporator coil for dirt/debris?
Have you checked/verified that the blend doors are working properly? They are in the HVAC box in the top of the cab.
Going off of memory, but I think this is a TXV system (thermal expansion valve), no orifice. I have seen a TXV fail before, but only one in 24 years, so I would have to say that it's not common and in my opinion is considered a last resort. A pressure gauge should show it plain as day.
What are your high and low side pressures? What is the vent temperature with the engine at roughly 2000 RPM and the fans on high?
Is the cabin air filter clean or new?
Someone mentioned vacuum. When the system is opened, you lose refrigerant obviously. More importantly, the system also gets air in it. Air has moisture. Vacuuming the system does many things. One, it removed the air. Two it removes the moisture, but it is dependent on temperature and the pressure. If the vacuum pump will only pull ~28", the moisture still in the system boils at 104 degrees F. But if it'll pull 29.92, the boiling point is around 10°F, and this is what removes the moisture. If a vacuum was not pulled, the dryer's desiccate is probably saturated, and to do the job properly you're going to have to replace the dryer again.
Oil. Many DIY'ers forget to flush the evap and condenser coils. There is oil in them, as well as the lines, dryer, TXV. In order to properly service the system, it all needs to come out and then be filled with the correct amount. If not done that way, you're guessing at how much is still in the evap, lines, and condenser (and dryer and TXV). An educated guess can get close enough to be acceptable, but it has to be educated;and I don't remember if the WSM shows how much to add to the compressor if is the only part replaced. Too much oil will cause as many, maybe more, problems than not enough. It is in more or less vapor form under normal fill conditions. If there is too much oil, it can hydraulically seize the compressor, which then causes all sorts of problems. Not enough, the compressor seizes from lack of lubricant and the same thing happens, you get to buy a new compressor....AND flush the ENTIRE system of the metal particles that were thrown about when the compressor failed.
Flushing with air. Not a good idea. Air lines have water in them, and you're just introducing water back into the system. You want ALL the water out. And ALL the air. Air is not a refrigerant. I like to use nitrogen to flush the system and check for leaks.
You're looking for vent temps to be 20-25 degrees below ambient; at the most. So if it's 100° outside, don't expect the vent temps to get much below 75-80 degrees. If it does, you have a great working system and don't mess with it until it's broken...and keep the condenser and radiators clean (and not just the screens either). I like to use a garden hose through the condenser and radiator to get the little stuff out. Do not use a pressure washer as it will bend the fins.
Is the belt slipping?
Why was the compressor replaced? They typically don't fail UNLESS the system is neglected...e.g-let the condenser get totally plugged and continuing operation for a long period of time. IIRC the compressor is a scroll type compressor-excellent design, very few moving parts, small, and tough. But not indestructible. Also expensive.
Have you checked the evaporator coil for dirt/debris?
Have you checked/verified that the blend doors are working properly? They are in the HVAC box in the top of the cab.
Going off of memory, but I think this is a TXV system (thermal expansion valve), no orifice. I have seen a TXV fail before, but only one in 24 years, so I would have to say that it's not common and in my opinion is considered a last resort. A pressure gauge should show it plain as day.
What are your high and low side pressures? What is the vent temperature with the engine at roughly 2000 RPM and the fans on high?
Is the cabin air filter clean or new?
Someone mentioned vacuum. When the system is opened, you lose refrigerant obviously. More importantly, the system also gets air in it. Air has moisture. Vacuuming the system does many things. One, it removed the air. Two it removes the moisture, but it is dependent on temperature and the pressure. If the vacuum pump will only pull ~28", the moisture still in the system boils at 104 degrees F. But if it'll pull 29.92, the boiling point is around 10°F, and this is what removes the moisture. If a vacuum was not pulled, the dryer's desiccate is probably saturated, and to do the job properly you're going to have to replace the dryer again.
Oil. Many DIY'ers forget to flush the evap and condenser coils. There is oil in them, as well as the lines, dryer, TXV. In order to properly service the system, it all needs to come out and then be filled with the correct amount. If not done that way, you're guessing at how much is still in the evap, lines, and condenser (and dryer and TXV). An educated guess can get close enough to be acceptable, but it has to be educated;and I don't remember if the WSM shows how much to add to the compressor if is the only part replaced. Too much oil will cause as many, maybe more, problems than not enough. It is in more or less vapor form under normal fill conditions. If there is too much oil, it can hydraulically seize the compressor, which then causes all sorts of problems. Not enough, the compressor seizes from lack of lubricant and the same thing happens, you get to buy a new compressor....AND flush the ENTIRE system of the metal particles that were thrown about when the compressor failed.
Flushing with air. Not a good idea. Air lines have water in them, and you're just introducing water back into the system. You want ALL the water out. And ALL the air. Air is not a refrigerant. I like to use nitrogen to flush the system and check for leaks.
You're looking for vent temps to be 20-25 degrees below ambient; at the most. So if it's 100° outside, don't expect the vent temps to get much below 75-80 degrees. If it does, you have a great working system and don't mess with it until it's broken...and keep the condenser and radiators clean (and not just the screens either). I like to use a garden hose through the condenser and radiator to get the little stuff out. Do not use a pressure washer as it will bend the fins.