What a time for the A/C to fail

[sunnyside360]

I have a 5 yr old Kubota M8200 cab tractor with 400 hrs and the A/C just started failing yesterday morning. At first, when the compressor would kick in, the air would be really cold. When it would eventually turn off, it would never come back on unless I turn off the A/C switch and then turn it back on. After a couple of hrs of mowing, the system died altogether. What a time for it to go on the blink -- supposed to be in mid 90's all week here in Central Pa. I keep the tractor maintained according to the service schedule and it's been "rock solid" up until yesterday.
Anyone have any ideas as to what the problem may be?

 

[Ductape]

I'm thinking low on refrigerant. Go buy some at the local auto parts store......the leak may be so small a little recharge may last the rest of the year. Don't know till you try.

 

[TripleR]

Agree with Ductape, I did that on one of my tractors this week. I will have my brother do a pressure check his next day off. The AC on my Case went out yesterday; had it worked on several times already, so it will go to the shop. Until then I will run it with the doors open and sweat AGAIN.

I am guessing you have checked your belts and made sure the compressor is kicking on.

 

[dstig1]

Don't go adding refrigerant to a system without checking system pressures! You need a set of AC gages to do that. Some auto parts stores will rent or loan them. You need gages that check both high side and low side pressures. Avoid Miracle in a Can products too. Put nothing into the system other than pure refrigerant, the correct system oil and UV tracer dye. (And you only deal with oil if you have to change out components.)

Checking belts is an obvious first step. Beyond that, the thing to check right off the bat are the compressor clutch. As the clutch wears, the gap opens up and it can cause the clutch to behave erratically as the coil can't pull it in far enough or strong enough to grab properly. Check the gap first with feeler gages. Most AC clutches I am aware of work with a gap of 0.015-0.030". You want to be on the lower end of that. There is probably a shim (thin washer) behind the clutch that you can remove to tighten the gap if this is the problem.

Other common problems can be the low pressure or high pressure cutout switches malfunctioning. They are typically cheap to replace, but I don't know Kubotas systems. Makign sure you have good airflow over the condensor is another thing to check. Back flush it out with a hose (not a power washer!) and compressed air, and check for obstructions and proper fan operation.

This is general AC troubleshooting advice as I have no direct experience with Kubota's systems, but vehicle AC systems are typically all about the same, with minor variations.

-Dave

 

[sunnyside360]

Thanks for all your input. The A/C was blowing very cold air when it was intermittently working . Just before it stopped working for good, I observed the clutch kick in and it was almost instantaneous cold air. Then all of a sudden, no more A/C. I guess it is time to invest in some gauges and check it out. Hoping to avoid having to transport the tractor to the dealer as it weighs well over 10,000 lbs with the cab, cast wheels, large tires filled with rimguard and FEL.
I did check & clean the cab filter and all cooling apparatus in front of the radiator. I did not remove the roof to check things there but maybe I should.

By the way, here is a link to what looks like very good A/C info. Troubleshoot Automotive Air Conditioning Problems

 

[rdsaustintx]

My air conditioners ONLY break on weekends in the dead of summer. Murphy got it right.

 

[TripleR]

Thanks for all your input. The A/C was blowing very cold air when it was intermittently working . Just before it stopped working for good, I observed the clutch kick in and it was almost instantaneous cold air. Then all of a sudden, no more A/C. I guess it is time to invest in some gauges and check it out. Hoping to avoid having to transport the tractor to the dealer as it weighs well over 10,000 lbs with the cab, cast wheels, large tires filled with rimguard and FEL.
I did check & clean the cab filter and all cooling apparatus in front of the radiator.

By the way, here is a link to what looks like very good A/C info. Troubleshoot Automotive Air Conditioning Problems

Good luck, I had someone come out and work on mine as my knowledge base is somewhat limited. The "fixes" did not last, so since my tractor is pretty big, I will have to have the dealer come and pick it up. If you can fix it all the better as a trip to the shop is always $$$$$$$$$, having to work with no AC is however even worse.

 

[sunnyside360]

My air conditioners ONLY break on weekends in the dead of summer. Murphy got it right.

Yea, I only wish it was my GMC Sierra A/C instead of my tractor. Then I could just drive the truck to the shop for repair. This Kubota M8200 is a beast.

 

[dstig1]

That's a decent website that I hadn't seen before. Gage sets are not real pricey - ~$100 or so for something decent, and they are the one tool you need for all AC work. I am real glad I got a set a few years back.

You can buy tools online. These places are good:
AC Source - Automotive Air Conditioning, AC Parts Tools Equipment Kits
Automotive Air Conditioning Parts & Equipment - WWW.ACKITS.COM
A lot of times you can buy them locally too, but some states restrict the sale of AC equipment (Wisc is like that, but Minn does not and I am on the border...).

This thread is a great step by step for recharging a system. Even though it is on a Ford Explorer site, it uses a VW as an example. Like I said, all AC systems are about the same...
http://www.explorerforum.com/forums/showthread.php?threadid=84675&referrerid=15286

Once you get past the issue that it takes a couple special tools like the gages, most AC repair is pretty easy. Shhhh, the shops don't want you to know that!

 

[lawn_king]

My kubota AC units have held up very well, (3030-3540). A failure after 5 years is not a shocking event! Dont forget these units get bounced around every time you use your machine. They dont sit in the shade on a concrete pad like your home unit! My 3030 unit would blow both cold & hot air at the same time if there was any grass bulid up at the base of the radiator, aside from that the unit worked great!