M7040 a/c

We had to do that on our L5030, fortunately it's east to acces in the roof.

Before you go too far, check to make sure the heater shutoff valve in the coolant line coming the engine is working properly. I have seen several A/C Systems on tractors not work properly because the coolant line valve was leaking hot coolant threw the heater core. Became more of a problem when manufacturers went to using plastic valves. Simplest fix is to put a manual valve in the line coming off the engine block.

From my experience it only takes a small amount of trash in the radiator to affect the cooling/ac system. It may look clean but small seeds will plug it up. Wash the easy stuff first and see if that helps.

Agree with BAP that the heater valve should be checked.

Also inside cabin air filter.

The WSM for the a/c under the seat starts on page 10-S44. Book flat time is 5 hours, just for under the seat.

Before tearing into it I believe that I would diagnose using pressures and temperatures to see what is out of normal.

If a dirty evap is indicated, then I would try first to remove ducts fitted to evap to access and clean air side of evap.

Welcome to OTT
IMHO one would have to ignore cab filters for an extended period of time or operate tractor with hole in cab filter or filter absent for evaporator to be the problem. Has both inside & outside filter been cleaned/replaced? Ditto on checking heater control valve or just install a manual heater cutoff valve in one of the heater hoses. I suppose the comp belt is in good condition & snug????
My M7040 AC cools very good down here in the Texas heat much better than the M4900 it replaced.

My dealer has no capability to do AC do I threw the tractor on a trailer and took it to Midas. They diagnosed, serviced and recharge AC for $149. I didn't need any parts replaced.

adventure bob said:

My dealer has no capability to do AC do I threw the tractor on a trailer and took it to Midas. They diagnosed, serviced and recharge AC for $149. I didn't need any parts replaced.

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Cost of having someone else service(check pressures/add refrigerant) of AC on my 2 vehicles/3 cab tractors is the reason I own gauges & refrigerant with no hauling/service call required. $149 will almost pay for 30#s of refrigerant & gauges cost about $60.

If both low and high side read normal pressures for ambient temperature, then it is not likely to be a leak. Maybe moisture in system, but

Most likely is the temperature motor and temp control. Hot water will also take out any cooling the a/c is doing.

Then if the system has to be opened maybe the receiver/dryer might be replaced if it has gotten saturated with water vapor. Triple evac if system opened.

There's quite a few things that can go haywire. I just did a M40 series cab a/c repair...have done quite a few lately it seems.

#1 thing to do is remove the screen from the radiator and the net from the condenser. Of course you've probably already done that. While the screens are out, use a water hose and WASH OUT the radiator AND condenser, and oil cooler if it's got it. Airflow across the cores is critical. How's the fan belt? If the fan slips, it'll cause issues...because the fan runs slower than it should. While checking that, look at the a/c belt. They have to be pretty tight. Snug usually isn't tight enough, not in my opinion. And of course both filters. There's the one in the cab top, and there's the other one behind the seat. All gotta be clean obviously-and sounds like you've already addressed those.

Now that you're done with the "easy" stuff, and if all that doesn't solver your issue, you're going to have to go into the box under the seat. When you take the seat plate out, watch the plate...they've been known to crack, so if you see cracks in it, replace it. I don't recall it being real expensive. Once the seat plate is out, you can see the top of the a/c box. There are some air diverter valves on it that are controlled by electric servomotors. The last couple I've messed with had the little plastic arm broken off. I can't say why-but I can certainly suspect. Anyway, the arm is not available separate from the entire box, so if one's broken, you get to fix it. To fix, remove the top half of the box...just got a few screws around the perimeter, and you'll have to work to get it out, but it WILL come out without removing the box from the cabin. Inside is some stuff you can clean out (heater core and evaporator)-easy to clean once the top's off. The one I was messing with last week had about 5,000 hours on it and inside the box was clean as a whistle but the arm was broken from the recirc selector door. Had to fix it with epoxy and a piece of mig wire; or customer could've spend about $3000 to replace the unit. $270 later, it was working perfectly-without discharging anything.

Seen one with a failed compressor...and the reason was due to a customer never cleaning the screen, radiator, and condenser. His other complaint was overheating. And of course he's been online saying how badly Kubota sucks because they can't build a compressor....well...they don't. IIRC, it's a Nippondenso scroll compressor. Scroll compressors are efficient and dirt simple but they are a little intolerant of excessive heat and/or neglecting to properly maintain the system. And when they fail, they spread failed compressor material throughout the entire system; if the system parts are not replaced or at the VERY least flushed, it'll take out the new compressor....and that's what this guy was griping about online (repeat compressor failure). I got the entire story from him in person and of course like normal, he doesn't tell it all while griping online. Funny how that works?

pressures. Dependent on ambient, but 175-250 on the high side and 25-35 low. Those are generalized and may vary with air temps. What are your readings? If you have a set of analog manifold gauges, you can see what's going on in the system sometimes by watching the needles....a very bouncy needle sometimes indicates moisture in the system (which should not be there unless the system has been opened at some point), etc etc. Mine are digital and easy to read but I hate that I can't watch the needles like the old style analogs.

190/35 psi. Could you tell us the outside air temperature? Or what time you measured it?

Know you're glad to get some cooling relief.

I am in the middle of an 8540. I believe they're similar.

Vent airflow "seems" fine. Pressures are 37 low and 200 high, ambient 89° and 72% humidity. Vent temps in the upper 60's so it's not blowing very cold. Noone has been into this system-and that is always a question to ask because many times people automatically assume that the refrigerant "needs to be charged" when the air begins to blow warmer than it used to.....

Anyway, I decided to have a look at the blend door, it's actuator, and the recirc door mechanism and it's servomotor. They all work ok, and the heater lines stay cold to the touch when the temp switch is turned to full cold-indicating that the valve is working. Onward. Removed the top cover over the evaporator, and found that it is TOTALLY plugged, I mean I don't see how any air gets through it--at all. The evap is removable but you do have use care in doing so. I cleaned the big loose stuff off with a light brush on a vacuum cleaner. The little stuff that's stuck between the fins required some chemical treatments and degreaser. Even then, I couldn't get all of the nastiness off of it...the operator is a heavy smoker and the tar stains just won't come out short of using an aluminum cleaner (which works great but the evap won't come out far enough to get it away from sensitive parts, so I can't use the caustic aluminum cleaner). Plenty of degreaser and it's about as clean as I can get it without totally removing it. Reinstalled, turned a/c on and now vent temps are in the upper 40's--which is about the best it will get with the ambient. Also worth noting is that the pressures came down, real low 30's on the low side and 175-180 on the high side. This is why I mentioned freon charge....unless the system has a leak, it shouldn't need any refrigerant charge "adjustment" at all.