Branson 6530C still having AC issues

[dclt736]

Thanks Tntcwg3, and my tractor does have a manual shut off for the hot water core and it is closed in the summer by me. Also my system does not use any sort of gates etc, the heating core is mount inline with the evaporator so air travels between both before entering the cab. This is how you control the AC output temperature, as if it is to cold in the cab, you add heat from the heating core to offset it. The temperature control knob open the hot water flow to the heating core, and is fully mechanical, not a measure of the air temperature and some sort of electrical control system.

 

[5030]

Thanks 5030, and very good comment. Last year i did a full inspection of the evaporator core, which is not a easy task, will post photos tonight as based on your comments i will do it again. I removed the cab lid last night so that we could check those fitting for leaks on Wed, but the evaporator is encased in a plastic housing holding the fans and heating core and it does take a fair amount of delicate work to separate the housing. Last year when we did the AC work, the inspection was done, and i can guess i most likely was the first person to see it since build. It was a little dirty then, but in no way was it plugged. I owned the tractor for over 8 years and had not AC issues up until last summer, and if the core was only a little dirty then, i do believe i will not find any real issue when i open it up. Photos to follow tomorrow. Also when the system was working after the refills, there was no smells that i picked up on, either damp, musty, of any sort of chemical smell say for the gas leaking. I am normally pretty good at picking up on that sort of thing, as well as changes in operating sounds. But all good advice coming from the chat so far.

Mine is the same way, all enclosed in a black plastic shroud that takes some work to get into besides removing the top. I do mine every spring and I shut off the heated coolant (WOG) valve as well. Newer tractors (at least Kubota) moved the works under the seat. Don't know if that is a better location or not far as cleaning it. Least it's not like a car where you'd have to take the entire dash apart to get to it.

 

[5030]

Never seen a heater control valve that didn't leak.

 

[dclt736]

Thanks 5030
True that the value could leak, so some loss of cooling could happen, but that would more then likely lead to poor cooling, not a complete failure to cool and also the lines from for the AC system would continue to be cold on the low pressure side and hot on the high pressure side and would also only have an effect as the tractor engine heated up. Which is not my problem, once cooling stops, i cannot get cooling again until the system has been pumped down and recharged.
I have had heard of times with some cars that the control door for air flow gets stuck in the heat side of the system and therefore no air flows over the evaporator to cool the car, so this is a valid concern on some systems, but i don't think it is at play here.
Regards less, i am going to post pictures of the evaporator uncovered later tonight and i am also going to pick up a new expansion value from the dealer tonight as they have one in stock.

 

[cbg8670]

Next guess from me would be faulty pressure switch..curious problem for sure

 

[RustyA]

Seconding that the evaporator is freezing up. Automotive usually has a sensor near or on the evaporator to cycle compressor when plenum gets too cold. One way to know for sure is to turn off compressor, leave fan on high for 15 minutes, then turn compressor back on. It should thaw with outside airflow. Usually frozen evaporator will restrict airflow volume

 

[Cougsfan]

Tractor AC's aren't really much different than auto ac's. It still does sound a lot like moisture, but you are right that it is strange that it can set for a couple days and not work for a short while after that.

One thing I have seen techs do when they are grasping at straws is to disconnect fittings throughout the system and blow air through each segment to insure there is no blockage anywhere. I would add if you dryer is saturated, holding a vacuum for 1 hour isn't long enough to dehydrate it.

Another thing to consider is the amount of oil in the system. Too much is as bad if not worse than too little. Most compressors come pre-charged with oil. Did your tech add oil?

Another thing I have seen some techs do on rare occasions is to purge the whole system with nitrogen prior to pulling a vacuum. I am guessing the logic behind that is bottled nitrogen is pretty moisture free.

I think the wrong amount of charge of Freon will affect the efficiency and performance, but won't keep the system from working at all.

A final thought. Working without gauges on both the low and high pressure sides is kind of like shooting in the dark. My Branson service manual has an excellent troubleshooting guide that is based mainly on the pressures that you are seeing.

 

[jaxs]

I think you realize how much harder it is to diagnose things with third hand information than it is in person. If what you said is accurate (100% of first charge was still in system when evacuated and recharged) the only thing that makes sense is admittedly far fetched but here gos. If high pressure side has over pressure protection,therein could lie the answer. Unlike low pressure cut out which cycles in and out as pressure gos up and down,high pressure switch must be manually reset (normally by pressing a reset button). When switch trips,the system will not work until reset. Pulling vacumm pulls switch back into reset position. At the risk of giving enough information to just make you dangerous,here's how to proceed. Low pressure switch interrupts + voltage,hi switch can interupt + or - so keep that in mind. Start engine and set ac to cool. If compressor is running (center bolt turning) but air isn't cool,stop here because the problem isn't due to hi pressure cut out. If compressor isn't turning,momentraily jumper 12 v + to clutch feed wire. If clutch clicks in and begins turning compressor,do not jerry rig and us it with jumper,track the problem down and fix it. Start at compressor looking for hi cutout. It will have wires leading to it. If found,rest should be obivous. Reset to see if ac works. If ac now works,guages must be used to see if switch is doing its job at excessive pressure or if it's defective and cutting out at lower than design pressure. It should be easy as coasting from this point on.

 

[dclt736]

Thanks Jaxs and others for your comments, will try to offer feedback to the last few in this one.
So the compressor does try to operated when the system is blowing warm, in this i mean that once i feel the system is not blowing cool air anymore, i have looked at the compressor operation to see what it is doing. And you can see the electric clutch engage for a second max, then sit idle for maybe 4 to 5 seconds and then engage again for a second or so, so it is in a rapid on off cycle.
And i do have a service manual that indeed does have a lot of information on the AC and it relations to pressure readings, but little trouble shooting that states what you would see on the compressor etc and the translations does leave a lot to the imagination.
There is a electric probe as part of the dryer, and if you disconnect it, the system will not run. There is also a probe of some sort attached in the air flow path of the evaporator outflow side but I do not know what it's function is. The expansion value is fully mechanical, no electric power or wires go to it.
As for compressor oil, the new compressor came pre charged with the correct amount of oil, and so we didn't add any more. Now i have seen a few youtube that we should have blown out the lines to get rid of any excess oil that would be left over from the old compressor, and as i installed the compressor, that was not done, so there is a small possibility that there maybe too much oil, but not sure if that is my problem.
I do like the idea of putting compressed air through the holes and cores to make sure there is no debris in there, and if we have to empty the system on Wed i will do that.
I also do not know if it is water in the system, as we did install a brand new dryer that was sealed before i installed it and the system has not been open that long to the air for moisture to really build up and vacuums have been pull, again if we empty the system on Wed, i will ask for a much longer vacuum time before refill.
I have attached images of the evaporator before and after opening it up and a video of the dust that came out with a compressed air hose. Yes there was some dust/dirt, but before i clean it i could see right through it, and same with the heater core, it had more dust on it, most likely because the condensation on evaporator washes some of the dust away.
Sorry seems i cannot upload a video.
I have not started the tractor since putting it into the shop last night.
Tomorrow after work I am going to start it up and see what happens when i turn on the AC, and will post that tomorrow.
Wed afternoon it will be at the garage and have gauges on it, so will see what they show and if we work out the solution, will post that as well.
Thank you to everyone that has offer advice.

 

[5030]

Yours is a heck of a lot easier than mine is to get too...