M8200 cab tractors

[Fedup]

Question for owners/operators of an M8200 cab tractor. How satisfied are you with the performance of the air conditioner? I'm presently working on one that seems to be under performing. Thought I might ask for some feedback from someone with first hand experience with one.
Judging by the system pressures, I would think it should be blowing pretty cold air, but the vent temperature only gets down about 54 or 55 degrees after a few minutes run time(at 2000 or so RPM) and slowly climbs back up. After twenty or so minutes is up to 75 degrees or more. This was today with ambient temps about 80. And no, the heater valve is not the problem. Both hoses are cool and even with one completely blocked off it made no difference. Evaporator and air box/passages are clean, so is condensor. Both seem a bit undersized to me, for the size cab and space to cool down. I even added an electric fan to the front of condensor which did drop the high side pressure about 60 or 70 psi but didn't seem to have much effect in the cab.

 

[ttpp]

What pressures do you have hi/low?
What is your temp drop from upper outlet to lower inlet @ condenser rad(as close to where pipes end before they go into the tubes?
Are your sure it's properly charged?
Just because pipes appear small doen't mean there under size a lot of these systems are designed to be very efficient & heat evaporation from items is just as important
Paul

Sent from my SM-A520W using Tapatalk

 

[Fedup]

No takers yet? Not looking for a bunch of questions, theory or explanations about how air conditioning works. Mainly hoping to hear from anyone with one of these tractors willing to share some feedback on how they would rate their particular system. Good, fair, poor, or what have you? Freeze you out even on the hottest days, or adequate but nothing to brag about. That sort of thing.

Thanks

 

[Tx Jim]

Is the heater control valve completely turning off flow of antifreeze?

The AC on the M4900 cooled fair on it's best day. The cleaner I keep rad/condenser the better it cooled. AC didn't cool very well if operating engine below 1500 rpm's. The AC on my M7040 is much improved.

 

[Fedup]

I've gotten mixed reviews about Kubotas. Some have told me their tractor's AC has been only fairly effective since new. Others say they have plenty of cold air. I don't work on a lot of Kubotas so I have very little to draw from. I know that some later models have been improved with larger evaporators and dual fans, and those do cool much better.
Usually I look at airflow through the condenser, airflow through the evaporator, the pressures, pressure differential, how/if it's cycling and decide from there what if anything needs to change. In this case, it all adds up to what I feel SHOULD be a properly functioning system, but it just doesn't work. I'm not giving up, just wondering where to go next.
That's why I'm asking for opinions on other tractors' performance so I have an idea what to expect when I finally get there.

 

[Bulldog]

My biggest problem with mine has been trash plugging the radiator and such. It only takes a small amount and the a/c suffers.
Weed seed have been the worst from my experience.

What to expect.

I don't have any numbers from inside the cab but this may help. Most of the time I run my fan on low because that's cool enough. I was mowing hay this week and it was close to 90. I turned it up on the 2nd notch late in the afternoon just for a little extra kick.
And I'll add, I'm fat and don't like being hot when I'm in a cab.

I do have my windows tinted which helps out more than you'd think. Good luck, I hope you get it figured out.

 

[Fedup]

Thanks.
Sounds like yours works pretty well. I believe the system in the M9000 is pretty similar to the 8200 even though the part numbers don't match exactly. The diagrams show the layouts to be pretty much the same.

 

[Bulldog]

I think the 6800, 8200 and 9000 and almost the same other than hp.

Now one of my neighbors has a 6800 that will freeze you to death. I wish mine would get as cold for sure.

 

[Fedup]

I was out on the 8200 again today. Did a more thorough job of mounting the fan to the condenser and tried it again. Checked the pressures again and decided to add a bit more refrigerant. It was running about 15/220 at full throttle the other day I was out there, with pretty dismal results in the cab.
I bumped it up to just below 20 on the low side. This brought the high side up to 300-305, still too high in my opinion. Made a noticeable improvement in the cab, though. It's actually comfortable in there now, but i still think the condenser is under sized. It's an early serial number tractor and the condenser is only about 11" square. The fan is 8" I believe and should probably be a 10". By the parts diagrams the later serial numbers had what appears to be a larger unit. Guess they did that for a reason.

 

[100 td]

A couple of things to consider. I don't know this particular tractor, the following information is of a general nature.
When charging a system with refrigerant that has a small condenser, any overcharge will reduce the available condensing capacity of condenser, especially if it has a liquid sub cooler as part of the condenser, or if it doesn't have a receiver. Therefore an overcharge will push the high side pressures up, add load to the system, and the quality of the refrigerant entering the expansion device will be reduced due to the quantity of flash gas it contains, thereby resulting lower potential heat absorption in the evaporator.
Generally a lot of fans on condensers (condensers that are engine/radiator mounted) really only assist when the engine is idling or the engine is at low speed, the condenser relies on air flow generated by the main engine fan and/or vehicle movement. Therefore it is essential that the main fan, fan shroud, radiators, radiators screens, transmission cooler, intercooler etc. are kept in a very clean state to achieve optimal condensing conditions for the A/C system.
Evaporators in trucks/tractors/equipment have the tendency to pick up a lot of dirt from either outside air flow, or internal flow from dirt in the cabins being bought into the machines continually on boots. Washing out the evaporators with a hose occasionally can have a dramatic effect on heat transfer.
Dual fan evaporators can suffer from one fan going out/slowing/or siezing and circulating air from one fan through the other back around the circuit on itself instead of going through the evaporator resulting in reduced cooling and possible short cycling.
If you have both fans running, and a good airflow across(through) your evaporator, measure the inlet air temperature and the outlet air temperature. If you are getting 10~12 degrees C difference then your evaporator is doing a good job.

Whenever doing any work on, or diagnosing a refrigeration or A/C system, you need to look at the system as a whole, as one thing can affect another and cascade or multiply the results, in many cases, not for the better if all parts of the system are not checked. YMMV

 

[BAP]

You could also have troubles with the Expansion Valve or partially plugged Dryer.

 

[Fedup]

All good advice and thank you. Because it's such a small system, I deliberately went light on the charge to begin with. First problem that came up was high pressure was approaching 400 psi with clean condenser and radiator. That's why we added the electric fan to begin with. As I stated earlier, my questions were aimed at this particular tractor, and you admit you're not familiar with it.

Also this has both a new expansion valve and drier, both OEM Kubota parts not aftermarket.

 

[100 td]

What charge weight did you load?

 

[dvcochran]

I know this is an older thread but thought I would put this out there in hopes it would help someone.
I have an early serial number M9000 with the smaller condenser. I have been through the similar hassles that most everyone with a 8200/9000 have. Here is a brief history of what I have done.
*Replaced dryer and expansion valve. Recharged and added oil. I overcharged (both oil and Freon) I think and the system performed no better to worse. *Pulled a long vacuum and recharged with only 2 can of Freon and the system worked much better.
*Added a condenser fan and it has helped a lot. Before the fan addition any time the tractor stopped (as in baling hay) the cabin would heat up even with the engine throttled up.

These tractors are undersized on the A/C system but IF everything is working and cleaned properly it is tolerable. The condenser is hard to truly get clean. It will look/feel clean but needs to be truly spotless. Removing the air filter housing and battery (easy) is the best way to make access and really get in to clean the condenser with a cable tie or other plastic tool. I use coil cleaner and it has done a good job as well. Do not use the caustic since it could damage other parts of the tractor.

Yesterday (7/26/19) I started having trouble with the clutch slipping. I have not determined if it is the clutch itself or a voltage problem yet. The last two days it has started slipping after working fine for several hours.

 

[SidecarFlip]

Besides an add on electric fan aiding the airflow through the condenser, it's imperative that the other end of the system is clean and insulated as well.

On my M9, I remove the roof every spring (older models like mine have the 'works' overhead). I blow out the evaporator and the heater core as well (I use mine in the winter for plowing snow), change the side mount intake filter and clean the back inside reirc screen. I also added foil-bubble-foil Reflectix to the inside of the roof panel to reduce the heat up there. That really made a difference in 'cool ability'.

I also added a WOG valve in the hot coolant line going to the overhead. I've never trusted the water control valves in any vehicle or tractor, been my experience they all bypass a certain amount of coolant and why have the ac fight the hot coolant.

It's easy to get to the underhood components, not so easy to get to the overhead ones but it's imperative that the overhead components are clean and free of crud for the system to work properly. I agree the system is marginal but then the cab space isn't that large anyway.

I have no issues with mine at idle or throttled up. The supplemental electric fan keeps the airflow sufficient through the condenser no matter what the engine drive fan is doing. As an aside, I zip tied the fan to the condenser instead of hard mounting it. Tat way, if I want to remove it for cleaning, it comes right out