Automotive Air Conditioning Information Forum

Well a 20% oil overcharge is not good.

If the system was designed for 5 ounces, the 6th ounce is 20%.

Yeah, but I doubt I could measure any difference in cooling performance with tiny changes like 1oz. OEMs will set the oil charge to an amount that is a balance between cost/performance/warranty, and my opinion is that it's usually cost vs warranty. I worked on a Chrysler vehicle 20 years ago that used ~200cc, our compressor supplier assured us that only 120cc was necessary for adequate lubrication in all conditions. We did not want to risk increased warranty for the oil cost savings. We were meeting our performance targets with even some margin, and we might have been "forced" later to come up with cost savings ideas, so no real need to make a risky change.

I'm picturing more like some different guys are always working on this tractor, every time they fix a small leak, they have no idea how much oil was lost, so just add 6oz "to be safe". Now maybe it's got 4x too much oil? Mr. No-roof is giving us not a very easy problem to solve.

Everything is perfect, there are no issues with anything, it just works terrible. If I take him at his word, it has to be something he can't see, or else something he doesn't think is important and can also spoil performance via high condenser pressure. Too much oil or too much air.

I’ve been mulling this over for awhile now. Aside from emptying each component of oil or at least trying to , how would you go about determining an oil overfill?

That seems to be a tough one. You can recover and reclaim refrigerant and some oil along with it, but not all the oil.

Experience can suggest that there might be too much oil in a system. Unfortunately, there's no dipstick or gauge that tells us definitively what that amount is. The only way is to remove all the old oil by solvent-flushing the components, with the exception of the TXV, lines with mufflers, and compressor. Then adding back the factory-recommended amount and grade.

The TXV can be reused if it's clean and was working before, while any lines with mufflers should be replaced. The compressor should be flushed only with the recommended oil a couple of times, then refilled one last time with the same amount of oil that originally drained out. The remainder is distributed appropriately to the condenser, evaporator, and R/D.

Is there any more information you can give us? Temperature of the suction line coming out of the evaporator? Discharge line Temperature and the pressures when you get these Temps?

Being under charged I'm pretty sure you liquid line Is running saturated. I think evaporator superheat probably very high, and I'm curious if Discharge line superheat is overly cool (too much oil or flooding TXV), or overly hot (air in the refrigerant)

Zip tie a thermocouple to a pipe section and insulate over it for an A+ grade, feel it with fingers for a B-

I'm still kinda curious what would happen with a little water sprayed or misted onto the condenser fins. This would at least let us know where some of the problem occurs - unable to shed heat from the condenser. And its a vanishingly inexpensive, easy test point.

Rick

A stuck-open TXV typically results in high pressures on both sides of the system, as you're seeing. If you can't take the tractor out of service for very long, go ahead and replace the TXV (recommend using an OEM part), evacuate, and recharge to the full amount. Then check the pressures and cooling performance at about 1,800 RPM. That shouldn't take but a half-day at most.

If you're still getting the same results, mist the condenser with water as previously suggested. In this instance, "no improvement" or "significant improvement" would indicate a condensing problem of some sort. Does it have air and moisture in it? Too much oil? Poor airflow? Partial internal blockage? Defective condenser? I don't know.

But at that point, if it were mine, I would pull it all apart, flush the evaporator, lines, and original compressor (the latter with oil only), replace the condenser and R/D, inject the proper amount and grade of oil, reassemble, evacuate, and recharge to specs.

I had a similar issue with my Kubota B2601. It sounds like there could be a problem with the expansion valve or maybe a refrigerant flow issue. In my case, it turned out to be a malfunctioning expansion valve that wasn't regulating the refrigerant flow properly, causing abnormal pressure readings. Once replaced, everything went back to normal.

Mr Bill wrote: ↑Wed Mar 27, 2024 5:18 am I had a similar issue with my Kubota B2601. It sounds like there could be a problem with the expansion valve or maybe a refrigerant flow issue. In my case, it turned out to be a malfunctioning expansion valve that wasn't regulating the refrigerant flow properly, causing abnormal pressure readings. Once replaced, everything went back to normal.

Is this and only "Mr. Bill"? Great to see you post again.

Mr Bill wrote: ↑Wed Mar 27, 2024 5:18 am I had a similar issue with my Kubota B2601. It sounds like there could be a problem with the expansion valve or maybe a refrigerant flow issue. In my case, it turned out to be a malfunctioning expansion valve that wasn't regulating the refrigerant flow properly, causing abnormal pressure readings. Once replaced, everything went back to normal.

This thread is nearly three years old, so you might not get a response from the OP. However, I'm interested in what the problem was as well.