M9540, installing new AC compressor. Took everything apart, flushed lines, evaporator. Cleaned evaporator fins with compressed air. New expansion valve, condenser and drier. Reassembled it all, added 3.85 ounces oil. Evacuated with 2 stage vacuum pump for 8 hours. Shut off pump and system held vacuum for 30 minutes. Begin charging r134a system. The temperature outside is 85 degrees F and in the shade. Open can tap, clear air from charge line to manifold. Open low side valve, gauge indicates flow. Pressures slowly rise. 30 minutes and can is still half full. I'm patient and the first 12 ounce can is empty. Connect 2nd can and open it up , running at 1500 rpm, the only indication the refrigerant is flowing is cold can. The high side pressure is 200 psi. The low side has reached 60 psi. Fan on high vent temp is barely cool. Thermometer not handy. The can feels almost full so not getting into tractor. Bring the tractor down to idle the low side pressure is 60 psi. High side dropped to 180psi. Leak checked with electronic tester. No leaks detected. During the charging phase I closed all the valves and changed the yellow hose. Still not getting refrigerant to move . I'm kind of stumped and am reaching out for some suggestions. Another thing, while tractor was running during this long term charging, I used my blow gun to blow air over through the condenser with no effect on pressures. I welcome any input. Thank you in advance
M9540 AC issue
- Thread starter bsamot69
- Start date
Are you charging on the low side? I am not familiar with your system, but does it have multiple ports? If so, could you be hooked up to the wrong port? Where did you put the oil, into the compressor or one of the lines? I usually pressurize the system with nitrogen after pulling a deep vacuum to make sure that everything holds. What is the temperature of the outlet air? If I have a problem getting the refrigerant out of the can, I put the can into a container of hot water to get it moving out of the can and into the system. I only use the large 30# cans and put them on a refrigerant scale so I know exactly how much I am installing. We all have our own ways of doing the job and the one that is best is the one that works for you. Are you using the top of the can to connect to the hose? If so, putting the can in a pan of hot water should be easy.
The oil is spread out some in compressor , in lines and evaporator. Charging thru low side. Blue valve. Yes. Thru top of can and can is upright. I'll try the pan of warm water, see if that works. The pressures look screwy and I'll get a thermometer for vent. The vent is barely cool.Are you charging on the low side? I am not familiar with your system, but does it have multiple ports? If so, could you be hooked up to the wrong port? Where did you put the oil, into the compressor or one of the lines? I usually pressurize the system with nitrogen after pulling a deep vacuum to make sure that everything holds. What is the temperature of the outlet air? If I have a problem getting the refrigerant out of the can, I put the can into a container of hot water to get it moving out of the can and into the system. I only use the large 30# cans and put them on a refrigerant scale so I know exactly how much I am installing. We all have our own ways of doing the job and the one that is best is the one that works for you. Are you using the top of the can to connect to the hose? If so, putting the can in a pan of hot water should be easy.
I would use hot, not warm water. The refrigerant in the can is going to cool the water. The hot water will cause the liquid in the can to vaporize and move through the hose. I would be using hot tap water, about 120-130 degrees. Just don't turn the can over because you don't want to put liquid refrigerant in on the low side. It can damage the compressor. My R12 machine has a canister that you measure the refrigerant into and then it warms the refrigerant as it puts it into the system on the high side. It was state-of-the-art back in 1970!The oil is spread out some in compressor , in lines and evaporator. Charging thru low side. Blue valve. Yes. Thru top of can and can is upright. I'll try the pan of warm water, see if that works. The pressures look screwy and I'll get a thermometer for vent. The vent is barely cool.
He installed a new expansion valve so I don't see that as being a problem, especially since he boiled out any moisture by pulling an 8-hour vacuum. Usually, expansion valves will crack if there is moisture in the system and ice forms on the inside of the expansion valve. You did jog my memory on one item that I had forgotten. Is the temperature bulb that is attached to the expansion valve properly attached to the evaporator and wrapped with cork tape? I am at a disadvantage since I have never had my hands on a Kubota air conditioning system. The principles are the same but the application of the hardware sometimes is different because of the peculiarities of the application.Agree with DustyRusty's comments.
I wonder if the expansion valve is working. Need to take temperatures on both sides upstream and downstream of the valve to troubleshoot.
Fabulous, took a pan of hot water, put refrigerant can and started charging can was empty in seconds! Too easy.
Okay so, full charge of refrigerant, ambient air temp is 82 f. 1500 rpm. High side is 250 psi. Low side is 55psi. The vent temp is 70f. Not what I was expecting.
Okay so, full charge of refrigerant, ambient air temp is 82 f. 1500 rpm. High side is 250 psi. Low side is 55psi. The vent temp is 70f. Not what I was expecting.
I checked both sides of xapansion valve. 100 degrees and 69 degrees. Also, while running at 1500 rpm I misted water on condensor, the high side came down to 150 psi the low side 45 psi. The vent temp went from 69 to 65 degrees. The in. And out of xpan block was 88 and 65 degrees. Ambient temp of 82. Perhaps I should add fan to condensor . The low side pressure seems so high and it seems it should be cooler at vent.
Next I would clean evaporator and condenser with outside coil cleaner.
I would also use my little hand held air flow meter to see if air is sufficient for heat transfer both evap and condenser.
Water misting says that efficiency is not there yet.
I would also use my little hand held air flow meter to see if air is sufficient for heat transfer both evap and condenser.
Water misting says that efficiency is not there yet.