Air Conditioning tests on L5030

[saflab]

Started checking the AC on my L5030 today since it is 68 degrees in the mountains of Virginia! Very strange weather for February. This tractor is my first Kubota and I have not history to speak of. I followed the directions in the operators manual. Engine speed-1500 RPM, Temperature control lever- Max cooling position, Fan switch- Highest blow, Air-conditioner switch-On.

I see only a transparent sight glass (no air bubbles) which means overfull or no refrigerant according to the manual. Using an infrared thermometer the ambient air is 68 degrees F and 58 degrees F out of the overhead vent. Is this enough temperature drop? It sounds low but I have not knowledge of AC systems. I have a bottle of R134a that was picked at Advance Auto last summer. Should I try to add refrigerant? The two ports are "H" and "L". Do I add to the "L"?

 

[Fordtech86]

You really need to put a set a gauges on it to see what the pressures are before doing anything!

If you do add, you will put it in on the low (suction) side (if it’s one of them cans from auto store with hose already on it it will only go on the low side fitting)

I wouldn’t recommend adding anything though without checking pressures first…

 

[Flintknapper]

Started checking the AC on my L5030 today since it is 68 degrees in the mountains of Virginia! Very strange weather for February. This tractor is my first Kubota and I have not history to speak of. I followed the directions in the operators manual. Engine speed-1500 RPM, Temperature control lever- Max cooling position, Fan switch- Highest blow, Air-conditioner switch-On.

I see only a transparent sight glass (no air bubbles) which means overfull or no refrigerant according to the manual. Using an infrared thermometer the ambient air is 68 degrees F and 58 degrees F out of the overhead vent. Is this enough temperature drop? It sounds low but I have not knowledge of AC systems. I have a bottle of R134a that was picked at Advance Auto last summer. Should I try to add refrigerant? The two ports are "H" and "L". Do I add to the "L"?

The sight glass really won't tell you much and you never want to see 'AIR' bubbles anyway. You would be looking for refrigerant in its gaseous state. AIR in a system is not good.

You need to put a set of manifold gauges on it and read the high and low pressures (with respect to ambient temperature). From that....we might be able to make suggestions.

 

[lugbolt]

The sight glass is a joke. Unreliable. Don't even bother with it.

do not charge the system unless you KNOW with 100% certainty that it's undercharged, and even then you need to know WHY. Most people go grab a can at the parts store, with a hose, and dump it in not knowing what the real problem(s) is/are. It should not be "low charged" unless there is either a leak or someone fiddled with it not knowing what they were doing.

A/C gauges are required for any work on the system. And just having the gauges means nothing unless the user knows what the pressure readings are telling them--and that in itself is almost an art. Experience is really the only way to know. Certified youtube mechanics? LOL!! Anyone want to take a guess how many times I've had to fix those certified idiots' mistakes?

there are a few things that can cause higher than normal discharge temps. Plugged condenser is the #1 cause. #2 being a slipping belt. They don't always squeak either. #3? Dirty evaporator--and that is in the top of the cab, not terribly hard to get into, and it IS (at least in my opinion) a yearly maintenance item. Condenser cleaning is a once a day maintenance item, more often if there is lots of chaff involves. Wash it all out, radiator, condenser, everything. Some guys don't like to use water but I've used water for decades and never once had an issue with it but I know what I'm doing. It has to dry out before you can put a bunch of dust back through it, or you can end up with mud which hardens up and the heat of the core can turn the right kind of mud into hard clay. BTDT.

In every single a/c performance issue I've dealt with, the very first things I look at are the condenser, belt and then the evaporator. Beyond that you need gauges and know how to interpret the data that they're spitting out. Usually addressing the first two fixes the majority of them.

 

[Fedup]

In the absence of gauges, you could try this. Go back to where you were, with engine running, system (supposedly) operating, and hopefully refrigerated air coming from the duct vents. After a few minutes operation, open the hood and feel the two lines on the compressor. The discharge line should be too hot to hold onto, and the suction line will be cold, to the point of frosting over. If you don't have that, it's time to find out why. And after only a few minutes run time, the clutch should not be cycling off and on. On max cool setting, until the cab really cools down it probably shouldn't cycle off at all.

 

[DaveFromMi]

I am assuming that Kubota uses TXVs to control evaporator pressures since there is a sight glass.
If properly charged, the evaporator outlet temperature should be slightly warmer (still cool) than the evaporator inlet. If there is a large difference between evap inlet and outlet (outlet line warm), then the system is likely undercharged.
TXV systems are charged to obtain 5-10° C superheat at the evap outlet. I doubt if there is a pressure tap at the evap outlet; it is probably closer to the compressor inlet; the superheat is higher at the compressor inlet.
If you confirm charge is low, look for leak points using yellow glasses and a black light. The refrigerant oil also seeps out at the leak point and will show up bright florescent under the UV light.
Before charging, it's best to completely evacuate the system and charge per the label. Overcharging could result in high side pressures close to cut out point (A/C shuts off), and/or liquid returning to the compressor.

 

[Tx Jim]

I agree with other posters never add refrigerants without monitoring both high & low pressures with gauges.

 

[ctfjr]

As several previous posters have noted the ONLY way to accurately tell what is going on in your ac system is a set of gauges / thermometer. That will allow you to measure superheat. Of course if 'superheat' is Greek to you . . .
Some of the causes of undesirable readings have been mentioned also but the right way to start is get a set of gauges on there.

 

[Tughill Tom]

I'll add and how to use and read a TP chart correctly!

 

[gmbc]

I'll add and how to use and read a TP chart correctly!

I have a B2650HSDC. It was low on refrigerant and added using the sight glass and gauges. The AC works for a short time but then shuts down the compressor just kicks out. What could be the issue. could there be blockage in the lines ? is there a filter in the line that may be plugged.

 

[Fordtech86]

I have a B2650HSDC. It was low on refrigerant and added using the sight glass and gauges. The AC works for a short time but then shuts down the compressor just kicks out. What could be the issue. could there be blockage in the lines ? is there a filter in the line that may be plugged.

What are the pressures doing while it’s running before it kicks out?

 

[Flintknapper]

I have a B2650HSDC. It was low on refrigerant and added using the sight glass and gauges. The AC works for a short time but then shuts down the compressor just kicks out. What could be the issue. could there be blockage in the lines ? is there a filter in the line that may be plugged.

Need to know the current pressures high and low side. Your system should have a binary switch (pressure switch) that will disable the compressor clutch if too little or too much pressure is realized.

There should also be thermistor of some sort on or about the evaporator that will also shut down the compressor if faulty, but usually just causes the the unit to cycle (which is its purpose). It keeps the Evap from freezing up.

Typically you'll want to start troubleshooting the AC system with pressure readings (high and low) using a manifold gauge set.