Had a buddy run a problem by me this morning...seems his John Deere 2950 is eating a/c compressors for some reason? He's on #3, it lasted a whole 3 hours...it's getting a new dryer & expansion valve every time, the pulley diameters are the exact same, pulleys are aligned, belt is just tight enough to do the job. He tried a new compressor from JD first, ate itself up in short order, the last 2 were from the local Auto Parts store, but they told him "no more" warranty on the compressors...he's an adequate wrench turner himself, but had an actual long time (& TERRIFIC) tractor mechanic install the last compressor thinking maybe he'd missed something when he'd installed them himself...but same thing happened.

Anyone got any ideas?

Try this over in the Tractors area of the site. Maybe someone has seen this happen before?

Also, what happens to them? Do they blow the seals or bearings or what?

Sorry, forgot to mention...the compressors are locking up.

moved here.

so how does he install them?

what kind of refrigerent and oil does he use in the system?

so how does he install them?

what kind of refrigerent and oil does he use in the system?
I'm not sure exactly how he installed the first 2, or what refrigerant/oil he used...whatever Auto Value stores carry.

As for the last install by the tractor place, I know they flushed the system and all that good stuff and hung the guages on it and all that jazz...not sure what ref/oil that guy used, but as I said above, he was the lead mechanic at our John Deere dealer for probably 20+ years, and folks would literally drive by other JD dealers just to have him work on their tractors, he's pretty darn good. But, this is apparently something out of the norm...

I would immediately suspect some kind of contamination in the system. Especially if the first pump crapped out like this, I wonder if metal shavings or something got into the system and now it is just eating pumps.

I don't know enough about AC systems though to know if a good vac/flush job would be enough to remove debris like this or not.

Is there an accumulator on the system? If not, one may need to be there to keep the oil near the compressor, since it's locking up I would suspect that the oil is getting away, causing this condition. Only other thing I can think of is, Is it blowing cold when it starts? Could also be the orifice is not working properly, allowing a lot of liquid refrigerant into the evaporator, which will eventually slug the comressor to death.

Could also be the orifice is not working properly, allowing a lot of liquid refrigerant into the evaporator, which will eventually slug the comressor to death.
Funny you mention orifice...seems the replacements were all smaller than the original he took out? Any correlation there??

Ok, now we're gettin' somewhere.....What type of refrigerant is in there? And is it the same as what was? A smaller orifice withe the same sized unit, and same refrigerant, will create more restriction, it will cool, but it will also create a high head pressure condition. With that high head will come heat, which may be thinning out or even vaporing off you oil causing the lockup. You mentioned in your first post it's using an expansion valve type metering device/orifice. If the refrigerant was changed to something else (most likely 134a) or was 134a to start with that valve needs to match the system. also, is the expansion valve with or without a remote sensing bulb? Sorry for all the questions, I'm an industrial HVAC/R mechanic by trade, but I have very limited experience with the automotive side. Most of the same theory applies though......Oh, and make sure that dryer they are installing isn't oversized. Those stupid things will soak up the newer oils like a sponge if they aren't sized right. I don't like using those unless I absolutley have to. Like in the case of a valve or winding burnout. Another thing to check would be the oil before the new refrigerant goes in. I don't know if the compresor has any type of sight glass or level reference point, but after the nitrogen purgge and the vaccuum is pulled, make sure all the oil that should be there is there.

in autos, you can get the lines so contaminated that they must be replaced. When a compressor locks up ,it spreads metal particles everywhere. After three compressors ,I would definitely replace a lot of parts,(or give up ,like I did in my 2555)

There's two major problems. First it's a 2950, a machine notorious for being underengineered. Second, a cab on a 2950 which is adding more problems on the already long list. Don't get me wrong, I love green. So much in fact that they write my check every other week. I'm a tech at a dealer and happen to have a 2950 split as we speak. It sounds like there's still contamination in the lines. I don't know how the orifice would look different, but it should have been the same as what came out of it. I'm not 100% sure, but I don't think the 50's would have had a fixed orifice. Most came with expansion valves, which eliminate the need for a clutch cycling switch. If in fact that is the case, with a fixed orifice and no cycling switch, that would definitely spell bad things. Like I said, this is just something I would start looking at. I know the later tractors of similar size w/ cabs had fixed orifices and cycling switches but I'm not sure on the 2950.

2950 should have expansion valve.

Did they replace the drier? Did they flush the line from the drier to expansion valve? Did they replace or remove and clean the expansion valve?

I've replace many a compressor because a drier came apart and plugged up the expansion valve on the older deeres is why I asked.

Flush that line real good, a new drier, and a new expansion valve, make sure the radiator and condensor are clean and your problems should go away.

I know there more expensive, but the deere compressors are hard to beat, I only use them now, had to many problems from the ones you get from the automotive side.

Good luck,

Did they replace the drier? Did they flush the line from the drier to expansion valve? Did they replace or remove and clean the expansion valve?
"Yes" to all...but, I'll be honest, I don't know that they did all of those at the same time (ie: the 1st time)...I should run into him in a couple of days, or for sure Monday morning, so I'll run it by him...

Funny you mention not digging the 2950...he's trying to trade the thing off last I knew, for a Kabota M series...!

It's like I said, I'm not really a huge fan of them. They're good running little tractors and very easy to drive and manuver and I think that's what a lot of people like about them. I've just seen the downside of them, but then when your a tech you only see the downside of every machine. If someone has a couple of acres and just wants a tractor to piddle around with then they're great. I just don't think they'll hold up to a lot of abuse, which we all know that anyone who owns a tractor hasn't used it like it was twice the size it really is.

i have a 2950 also a 3255 same ac setup. dont know where your getting these compressors but make sure the correct oil is going in them. most pumps i am seeing is pag oil 46 viscosity. there is also 100 viscosity and ester oil. these oils can not be mixed. systems have to be taken apart and flushed. i believe the 2950 calls for 11 oz of oil. also the codenser is a major area where dirt and metal will collect, flush or replace. after that many pumps, i would be considering a complete ac system replacment. buy the oil from a ag supply outfit such as hy-capacity, ap air inc or such. make sure system is evacuated and do not overfill. as said in previous post dryiers and expansion valves are automatic.