Kubota's with Roof Mounted A/C system

[dvcochran]

I have a M9000 with the blower/evaporator housing mounted above the cab. Recently the compressor locked. I finally recieved all my parts/tools and did the repairs Monday & Tuesday. Replaced the compressor, condenser, expansion valve, and receiver/dryer. Flushed the lines and evaporator and replaced all O-rings. Pulled a log vacuum and found I have a leak at the exp. valve. I had nicked the new O-ring. Replaced and pulled vacuum again. Left the tractor over night and it held good vacuum. Recharged the system and it is working well. However, temperature coming out of the vents isn't as cold as I think it should be. I had the tractor in the shop so in the shade, the ambient temp was hot at 96°, the engine was not super hot and the discharge air temp was just under 60°. Any suggestions?

I ran the tractor the last two days and can definitely tell the system is better than before. You can really tell when the sun is out hitting the roof and warming up the air going into the evaporator/blower intake. I have added some insulation (thin reflective like goes under a metal roof). Has anyone tried anything else to insulate the roof/intake air?

 

[200mph]

I'll assume you checked operating pressures after filling to verify the system is working as intended.

Perhaps check the airflow at the condenser to make certain it is getting adequate airflow. Belt tension and screens would be on my list to check.

Also believe someone on the forum added a small electric fan to the condenser to aid air flow and it helped operation.

Please post back what you find.

 

[SidecarFlip]

Me....

You need to add a 12 volt electric cooling fan in front of the under hood condenser blowing backward. I wired mine to the electro-magnetic ac clutch via a 12 volt relay (because the fuse for the clutch won't handle the amperage the fan draws.

Problem is air flow through the underhood HX. Too many heat exchangers in front of the engine fan so airflow is minimal and so is heat exchange is minimal and the ac HX is small to begin with.

I would also increase the cab window tint. The heavier the tint. the less radiant heat is absorbed, the the better the ac will cool.

I used foil-bubble-foil 'Reflectix' in the cab roof, stuck it on with 3M contact cement.

Finally, you might want to add a shut off valve in the coolant line that feeds the heater core. . Modulating valves are prone to leak and pass hot coolant so the AC is always fighting the heater. That is SOP on big trucks btw.

Mine will freeeze me out, no matter how hot it is in the field.

Any or all 'improvements' will help a lot.

 

[SidecarFlip]

I might add, you really need to remove the roof at least every other year (I take mine off every spring) and blow the dust out of the components and change the cabin outboard air filter at the same time (depending on how much dust and chaff you run in in the field). I run hay so I get a lot of dirt up there, despite the outboard air filter.

I blow out mine every spring.

 

[lugbolt]

Evaporators are hard to get perfectly clean especially after a compressor failure. There may still be some junk inside it. That'll reduce it's ability to cool. Also the flush agent is VERY hard to get it all out as well and it, too will reduce efficiency. IMO (and it's just my opinion), when a compressor fails, every single part of the system that has refrigerant in it should be replaced in order to be 100% sure all the compressor failure garbage is removed from the system.

I did an L40 last week same issue, compressor died. Upon removal of the evaporator, I decided to cut it open and peek inside the tubes. Full of black, caked oil.

 

[dvcochran]

The pressures were 35/260. The cabin filter is new. There is tint on the small windows but had already removed tint from the doors last spring. Just could not see in dust or dark. I also added a condenser fan back in April. It also makes a difference.
The system is definitely better after the repairs, tolerable and holds off the sweat. This style fan system just does not move much are compared to the other tractors I run (JD 6210 & NH 4.65) where the evaporator is down low and run dual fans.
Has anyone had experience with ceramic window tint that is not very dark or adding an insulated duct from the cabin intake screen to the blower fan intake?

 

[lugbolt]

Take the roof off and put some reflective insulation panels on the bottom of it. That helps. Ceramic tint is supposed to work very well, though I haven't tried it (yet). Look at 3M tint products. 3M is usually a step above the other brands, but it's also the most expensive and for that, places that do window tint usually don't carry it. 3M advertises their top of the line "tint" (I think there's some clear film) that blocks 95% of UV and a big percentage of IR. I'd like to try it if I can find anyone to install it. I just can't do it. Have tried and failed several times and don't trust myself anymore.

With those pressures I'd like to think there's still some air in the system. That tractor should be in the mid 60's after running a few hours even out in the heat.

I forget where the reflective panels came from but it was self-adhesive. People raved about how well it worked. I have to put a headliner in my car and if I can find out what the stuff is, I am planning on putting that stuff on the car too. It's a/c works ok but the car is dark colored, old, and currently has no clearcoat so it's interior temps get up around 200 degrees if it's sitting out in the sun all day (and it does on a daily basis). The rear view mirror's ball swivel actually melted and was dangling on the wire harness when I went to get into the car after work yesterday.

 

[eserv]

anyone converting to a HC based refrigerant?

 

[chim]

Unless something has changed, our beloved government believes that HC refrigerants for existing equipment should be illegal. It's OK for some brand new equipment specifically designed for it.

 

[torch]

anyone converting to a HC based refrigerant?

I tried it once with a car (01 Buick Regal). It was OK, but subjectively I felt it was not as efficient as R134a, and I converted back a year later.

HC is a lot easier for the backyard mechanic to get his hands on up here north of the border in Ontario. The small cans of R134a have been banned and they are starting to crack down on buying the 30# cylinders without an HVAC license.

 

[eserv]

I tried it once with a car (01 Buick Regal). It was OK, but subjectively I felt it was not as efficient as R134a, and I converted back a year later.

HC is a lot easier for the backyard mechanic to get his hands on up here north of the border in Ontario. The small cans of R134a have been banned and they are starting to crack down on buying the 30# cylinders without an HVAC license.

I have Duracool in my 1996 GMC full size van. Cools great! only problem is that the engine idles to fast with the AC on now where it didn't before. High side pressure is considerably less with HC

 

[SidecarFlip]

Take the roof off and put some reflective insulation panels on the bottom of it. That helps. Ceramic tint is supposed to work very well, though I haven't tried it (yet). Look at 3M tint products. 3M is usually a step above the other brands, but it's also the most expensive and for that, places that do window tint usually don't carry it. 3M advertises their top of the line "tint" (I think there's some clear film) that blocks 95% of UV and a big percentage of IR. I'd like to try it if I can find anyone to install it. I just can't do it. Have tried and failed several times and don't trust myself anymore.

With those pressures I'd like to think there's still some air in the system. That tractor should be in the mid 60's after running a few hours even out in the heat.

I forget where the reflective panels came from but it was self-adhesive. People raved about how well it worked. I have to put a headliner in my car and if I can find out what the stuff is, I am planning on putting that stuff on the car too. It's a/c works ok but the car is dark colored, old, and currently has no clearcoat so it's interior temps get up around 200 degrees if it's sitting out in the sun all day (and it does on a daily basis). The rear view mirror's ball swivel actually melted and was dangling on the wire harness when I went to get into the car after work yesterday.

I think you can buy Reflectix adhesive backed and I know Farm-Tek sells their own brand with adhesive backing but it was just as easy for me to use 3M spray contact adhesive applied to the underside of the roof and stick on pre cut to size Reflectix panels. My largest improvement came from installing a WOG valve in the coolant line to the roof. Don't matter is it's in the feed or return, just so long as it stops the flow of hot coolant and is accessable for cold weather use.

 

[chim]

Here's the discharge temp on my 4240 with the door set for recirc. It's about 4 degrees warmer with the door set for fresh air. I had planned on gluing that foil bubble insulation in the roof, but never got around to it.

 

[SidecarFlip]

Here's the discharge temp on my 4240 with the door set for recirc. It's about 4 degrees warmer with the door set for fresh air. I had planned on gluing that foil bubble insulation in the roof, but never got around to it.

Careful with the discharge temp, you are pushing a frozen up condition...

I forgot to add that the one modification that I did that made the biggest impact on cab cooling was the addition of a WOG valve in the heater circuit. Almost every one of the neater control valves leak a bit of hot coolant so the ac is always fighting hot coolant.

 

[Jms63]

Me....

You need to add a 12 volt electric cooling fan in front of the under hood condenser blowing backward. I wired mine to the electro-magnetic ac clutch via a 12 volt relay (because the fuse for the clutch won't handle the amperage the fan draws.

Problem is air flow through the underhood HX. Too many heat exchangers in front of the engine fan so airflow is minimal and so is heat exchange is minimal and the ac HX is small to begin with.

I would also increase the cab window tint. The heavier the tint. the less radiant heat is absorbed, the the better the ac will cool.

I used foil-bubble-foil 'Reflectix' in the cab roof, stuck it on with 3M contact cement.

Finally, you might want to add a shut off valve in the coolant line that feeds the heater core. . Modulating valves are prone to leak and pass hot coolant so the AC is always fighting the heater. That is SOP on big trucks btw.

Mine will freeeze me out, no matter how hot it is in the field.

Any or all 'improvements' will help a lot.

Man I would love to see a pic of how you mounted that fan ,do you feel like that made the biggest improvement to keeping your air cold.. I’m fixing to try something on my mx6000

 

[torch]

Flip hasn't been on this forum for several years.

 

[Fedup]

Adding an electric fan isn't a "Flip only" design, by any means. I've mounted them on a number of tractors, not just Kubota. I find that all too often the airflow through the condenser is somewhat lacking on many tractors for various reasons. Sometimes the space between the condenser and radiator is just too great. Sometimes there are just too many other coolers stuffed in the same area. Sometimes the condenser is simply too small. (just my opinions here)

If you're interested in trying it out, it's a pretty simple experiment. Start with the largest fan you can find that will fit in the space available, and cover as much of the condenser as possible. You can start by anchoring it with tie straps for openers. Make up some jumper wires to connect it directly to battery positive. Try to do a good enough job of it so you can operate the tractor doing whatever work you want with it for a while. Run it that way and see what difference it makes. I prefer to have gauges attached to the A/C service ports to evaluate the difference in pressures with the fan running or not, but that's not to say you really need that for a quick experiment.

 

[jaxs]

Before adding an auxiliary fan check everything for cleanness. Use lights and mirrors if neccessary to see between radiator,grill,screen,coils and such. Check between fins for dirt and duff. While engine is at ambient temperture backwash coils with garden hose. Don't use any kind of coil cleaner unless you are absolutly certain the chemicals are intended for EXACTLY what you are doing. Many coils are ruined every summer using improper cleaners and or improperly using cleaners. Dish washing soap is all you need and there's no way it can harm anything. Don't overlook coils in evaporator and evaporator fan blades. If either are dirty performance will suffer. Heed what someone said about installing a manual valve to stop coolant flow through heater coils. Make certain someone hasn't removed fan shroud,it plays a big roll in engine cooling. See if coolant fan has thermostatic control and if so it's working. If you add a fan make certain it doesn't block as much air as it adds. I would opt for heavier coolant fan blade rather than trying to boost flow with an electric fan.

 

[Jms63]

Adding an electric fan isn't a "Flip only" design, by any means. I've mounted them on a number of tractors, not just Kubota. I find that all too often the airflow through the condenser is somewhat lacking on many tractors for various reasons. Sometimes the space between the condenser and radiator is just too great. Sometimes there are just too many other coolers stuffed in the same area. Sometimes the condenser is simply too small. (just my opinions here)

If you're interested in trying it out, it's a pretty simple experiment. Start with the largest fan you can find that will fit in the space available, and cover as much of the condenser as possible. You can start by anchoring it with tie straps for openers. Make up some jumper wires to connect it directly to battery positive. Try to do a good enough job of it so you can operate the tractor doing whatever work you want with it for a while. Run it that way and see what difference it makes. I prefer to have gauges attached to the A/C service ports to evaluate the difference in pressures with the fan running or not, but that's not to say you really need that for a quick experiment.

I’m prolly going to try that, appreciate the info

 

[Tx Jim]

Flip hasn't been on this forum for several years.

But he can be easily found on Tractorbynet