Improving the Kubota AC on cab tractors....

[5030]

Back when I owned my 5030, I initiated a thread on this site concerning the modifications you could do to improve the airflow (negative) through the ac condenser and oil cooler.

Kubota places both the ac condensor and oil cooler (and ata units) fairly far from the main radiator core and fan. This creates a less than desireable air flow through the condenser and oil cooler(s) when the engine isn't turning rated rpm.

I eliminated the air space on my 5030 by placing rubber strips between the condenser and the radiator itself, effectively closing off the space between and creating a much more negative air flow pattern that resulted in better ac cooling and cooler HST temperatures.

Both my M9 and my 105 are configured similar but also have ata units to cool the intake air heated by turbocharging. While the ata unit is removed from the radiator itself, it still functions properly because the boost and elevated intake air temperature only comes into play at high load and higher rpm and the radiator fan can provide the needed airflow.

Not so with the ac condensor and the transmission cooler. They are both located lower down in the belly of the engine bay. There is little negative air flow at lower engine speeds. Consequently, the ac condensor and oil cooler loose efficiency resulting in less refrigerated air in the cab and to a lesser extent, elevated oil temperatures (not a big concern as both tractors are gear drive, not HST).

What I did, was mount a 12 volt slim profile radiator cooling fan in front of the ac condensor, wired through a 30 amp relay to the ac electromagnetic clutch so when the clutch is energized, the cooling fan is as well. I used a 7" diameter 1550 CFM unit (available on Flea-Bay) mounted to custom fabricated cross rails that span the framework that mounts the condensor and oil cooler. I mounted the fan behind the net that keeps the condensor/cooler assembly free of chaff.

Now, on hot days, the cab is cool if not cold at reduced rpm. I still need to clean the net a couple times a day in the field, but even with chaff on the net, the condensor is doing the job appreciably better than before.

I may get lazy at some point and istall a reversing switch so I can use the electric fan to blow off the net.

 

[TripleR]

Do you have a link to the modifications on the L5030 AC; guess I am having a senior moment and can't find it. Thanks.

 

[5030]

That was a long time ago. I did that thread about 7 years ago......I think Slowzuki knows where the thread is and possibly modified his.

Basically, I shrouded the space between the condensor and HST cooler with cut rubber strips I cut from an old mudflap so I could still get the radiator screens out but it increased the negative air space between the engine fan and the condensor. I used wing nuts on rivet studs to mount the rubber so I could remove it to clean the radiators. Hay and wheat straw makes a lot of chaff so blowing out the radiators is an everyday chore.

I'm in the process of doing the M and the 105 plus adding the electric fans to work with the ac clutch.

For some strange reason, Kubota likes to mount the condensor too far away from the main radiator and not close off the side space. The ac is light years better on the big tractors than it was on the 5030 but it can be improved upon. The most efficient placement of the condensor is as close to the cooling fan as possible, which is why, on your automobile, the condensor is laying on the radiator front with only a small space to insulate it from the engine coolant heat.

I thought the low mount ac on the 105 would be an improvement over the cab top ac on the M, but it's not. In actuality, I prefer the high mount. I have bad knees and the vents on the dash blow the cool air on my knees and I don't like that. I think the only thing on the 105 that's an improvement is the front windshield wpier. The cab light are cute but the old style on the M are brighter at night. The M is a square hood, the 105 is sloped and the M has it's exhaust right through the hood, the 105 is side mount. I'm used to the hood exhaust and a square hood. Either way is fine. actually. I've also considered pulling the muffler on the M. It takes quite a bit of engine bay space. besides a straight piped turbo engine has a sweet sound when spooled up.....

Back to cooling your body.....

I also suspect that increased negative pressure zone will be an improvement for the ATA intercooler too. The cooler the charge air is, the more dense it is and that produces more power with less fuel, not that Kubota's aren't stingy on fuel anyway.

The issue on the M is the multiple screens. There are no less than 4 screens for the various heat exchangers and they all exit from the left side.

I'll have to do some pictures, before and after.....

 

[TripleR]

Thanks, mine works OK now, but when it is really hot, I have to keep the RPM's up a bit.

 

[5030]

Thanks, mine works OK now, but when it is really hot, I have to keep the RPM's up a bit.

...a direct consequence of 1. The location of the condenser in the air flow path and 2. Possible buildup of debris on the screens.

Eliminating the open space (between the condenser/cooler units and the main radiator will go a long way toward improving efficiency and regular cleaning of the screens and fin tubes helps too.

The big thing I was noticing was, in the field, taking a break (for a liquid refreshment) and idling the tractor, the ac was appreciably warmer at the vents, especially in the afternoon with the sun cooking me. The ac unit should provide a comfortable enviroment at all rpm ranges, from base idle to rated pto rpm.

The amount of glass, though tinted (on both tractors) necessitates serious BTU transfer for comfort. At least in the winter, the heaters are both up to the job.

I'd prefer the now outlawed R11 over the 134a. R11 is a much better medium for BTU transfer than 134a. 134a is 'enviromentally friendly' but not as efficient as R11.

 

[TripleR]

I keep my screens clean and it does help on our 5030 and 8540. My son in law owns a car window tinting business and I considered having tint put on, but decided against it.

I have a full service HST fluid etc coming up pretty soon and will try to figure out blocking the space while I have it in the shop.

I completely agree on the refrigerants. My brothers have some of the older ACs on their vehicles and some refrigerant squirreled away. I remember when you could see the air coming out of the vents on my cars it was so cold.

Thanks for the info.

 

[5030]

I had the modified M sitting in the lane this afternoon, idiling. I'm getting the mower ready and taking off the FEL. I was amazed...at idle it was COLD in the cab and it was 85, muggy and sunny and it was in the sun. Lots of condensate coming from the cab drains. Much better than it's ever did before. The electric fan whizzes away, I can hear it as the compressor cycles.

Now, if Kubota would wise up and change the ac outlets like JD has, so you can fit a Pepsi can in the vent (or a Budweiser) whatever you prefer, that would be ****.:thumbsup:

Nothing beats a 'cold one' in the field.

You can still get R11, for a price but it's not compatible with the internal parts in a 134 system.

 

[Tx Jim]

Adding the electric fan in front of condenser is an excellent idea. IMHO Kubota needs to learn a few things about 100 plus degree weather especially Texas weather. The radiator & condenser on my M4900 is about the right size for a compact car.

 

[blueriver]

I had the modified M sitting in the lane this afternoon, idiling. I'm getting the mower ready and taking off the FEL. I was amazed...at idle it was COLD in the cab and it was 85, muggy and sunny and it was in the sun. Lots of condensate coming from the cab drains. Much better than it's ever did before. The electric fan whizzes away, I can hear it as the compressor cycles.

Now, if Kubota would wise up and change the ac outlets like JD has, so you can fit a Pepsi can in the vent (or a Budweiser) whatever you prefer, that would be ****.:thumbsup:

Nothing beats a 'cold one' in the field.

You can still get R11, for a price but it's not compatible with the internal parts in a 134 system.

Can you put up some pictures.

 

[TripleR]

I had the modified M sitting in the lane this afternoon, idiling. I'm getting the mower ready and taking off the FEL. I was amazed...at idle it was COLD in the cab and it was 85, muggy and sunny and it was in the sun. Lots of condensate coming from the cab drains. Much better than it's ever did before. The electric fan whizzes away, I can hear it as the compressor cycles.

Now, if Kubota would wise up and change the ac outlets like JD has, so you can fit a Pepsi can in the vent (or a Budweiser) whatever you prefer, that would be ****.:thumbsup:

Nothing beats a 'cold one' in the field.

You can still get R11, for a price but it's not compatible with the internal parts in a 134 system.

I am not familiar with the JD vents, but prefer those on our 8540 to the ones on the 5030 that blow pretty much on your head. I still like our 5030 though.

My brother owned his own garage, so the R11 he has was purchased then. Around here you can't buy R11 without the proper paperwork. In time they will retrofit to the new units or drive with the windows down I suppose.

I too would like to see pictures of your conversion on your M.