Is my air conditioner malfunctioning?

[Tony M]

G'day All

Greetings from Sunny South Australia:thumbsup:

I've previously posted about widening the track on my 3720Cab with skidsteer wheel spacers. FWIW, I remain convinced this was one of my best decisions.

But, on another topic, I'm really wondering if my a/c system is faulty. It's certainly not like any car system I've encountered in that the air is slightly cool at best and warmish at worst. It certainly failed to keep the cab cool today at about 29C (about 84F) ambient temp and no solar load - it was quite overcast.

I looked in the manual and it mentions the compressor clutch. Well this is obviously switching the compressor in periodically - about every 30 to 60 seconds for about 7 to 10 seconds. This seems to be more frequent cycling than a car a/c unit? I would've thought it would need to stay on longer if it wasn't coping with the cooling job.

The tractor has only done about 45 hours and is still under warrantee, so I'll ask the dealer on Monday, but I thought I'd see if any of the clever blokes on this site had any words of wisdom to offer.

At least it would be nice to know if the unit should be able to keep the cab cooler than outside on an 80 degree F overcast day.

Any opinions or advice would be very welcome.

Cheers
Tony

PS I have read the manual and I do have the settings of the controls right - ie both knobs fully anti-clockwise, a/c switch on and fan on.

 

[sandman2234]

Cycle that often will burn up the clutch on the compressor. Get it to the dealership soon.
David from jax

 

[greg_g]

At least it would be nice to know if the unit should be able to keep the cab cooler than outside on an 80 degree F overcast day.

PS I have read the manual and I do have the settings of the controls right - ie both knobs fully anti-clockwise, a/c switch on and fan on.

My AC worked fine from the beginning, keeping the cab cool with ambient temps in the high 90s. But when it started turning cool this fall, I was disappointed at the poor heating. Turns out that the heater control was out of adjustment, to the point where the hot water valve at the heater core was barely opening.

I'm relating this experience to point you towards the heat/cool control wires. They start behind the control panel inside the cab, run toward the rear, turn the corner, and end at the heater core/AC unit. Your problem could be that either the AC control wire isn't adjusted for max output, or the heater control wire isn't adjusted to completely turn off the heat. Or both. To fix it properly takes two techs. Two are needed to safely remove the roof cap without damaging a seal. Then one sits inside watching the control knobs, while the other is behind the tractor adjusting the opening/closing positions at the heater/AC end

My issue was corrected under warranty.

//greg//

 

[hizoot]

I doubt its the heater control lines not shutting off heat....as the compressor is short cycling either on the low or high pressure switch. Low pressure= low on refrigerant or blocked inside/evaporator coil(not enough air flow)....Hi pressure switch= overcharged (too much refrigerant) or blocked airflow of the high side (outside/condensor coil). If the problem was due to heat not switching off all the way and intermixing with the cooling,then the a/c would just run constantly and still not blow cold but no short cycling.

So yes...your a/c isnt right. Either one of the coils is clogged with dirt/restricted air flow/fan issues...or its a refrigerant isssue.

 

[blueriver]

My cab tractor did the same thing and frustrated me ... I called an a/c guy who came to the field. I parked under a shade tree ... he put the gauges to it, smiled and said we need a water hose ... drove to the house and he flushed the coils in front of the radiator ... removed a couple bolts so he could get to it good and about 15 minutes and $75 later I was back in the field nice and cool. That dust and crap really packs into those fins and restricts the air flow.

Now ... I had always thought that I had kept the front blowed out real well with air, guess not. I'm more detailed about that now.

May not be your problem ... may not hurt to check it.

 

[Glen Watkins]

Did you have a radio installed when you bought the tractor? This used to be an issue because the roof had to be pulled to install the radio and if the installer was not careful the roof seals would get damaged.

 

[sunnyside360]

I have a 3720 cab tractor and have experienced the same as you. The first time it turned out to be the roof seal was damaged and Deere replaced it under warranty. I suspect the seal was damaged when the radio was installed at the dealer when new as others also have experienced here on tbn. In this case my A/C was anemic right from the beginning when new.

The second time the cooling was very anemic was caused by debris plugging the coils in front of the radiator. The compressor clutch was cycling fairly quick like yours is doing. I normally use compressed air to clean the front but over time stuff can really get jammed in there. I'd give your front radiator, oil cooler, and A/C coils (all in front) a good cleaning.

 

[tomd999]

Hi,

I would try cleaning the condenser first. The passages between the fins are small and chaffe and dust can block them in no time, especially if your mowing in dry conditions.

When I use mine in dusty conditions, after I'm done and about to go in the barn, I pop the hood open and give everything a blast with the air hose. I blow the radiator, coolers and condenser from the rear forward to clear them out. You would not believe what I get out there after a good day of field mowing.

Also, once a year I wash them with a solution made by Everco for exterior cleaning of radiator and ac condenser fins, it is non corrosive but really cleans out what shouldn't be hiding in there.

My 2 cents,

Tom

 

[Bird]

My cab tractor did the same thing and frustrated me ... I called an a/c guy who came to the field. I parked under a shade tree ... he put the gauges to it, smiled and said we need a water hose ... drove to the house and he flushed the coils in front of the radiator ... removed a couple bolts so he could get to it good and about 15 minutes and $75 later I was back in the field nice and cool. That dust and crap really packs into those fins and restricts the air flow.

Now ... I had always thought that I had kept the front blowed out real well with air, guess not. I'm more detailed about that now.

May not be your problem ... may not hurt to check it.

I saw the same thing happen with an almost new Kubota being used to cut and bale hay a few years ago.

 

[jenkinsph]

I agree with cleaning the condensor coil first washing from the rear forward. While at it clean the cab air filter too, just to keep everything clean. If you don't see an immediate improvement, lowered air temperature and longer cycle times you may have a low refrigerant level. I would expect to see about 55F air coming out the vents after 10 minutes of run time if the outside air temperature is around 85F ( I am not good with Celcius stuff:ashamed

If this doesn't fix the problem you need to get it fixed asap as it will cause problems with the clutch.

 

[Tony M]

Well, huge thanks to everyone for those really helpful replies.

At first I was a bit skeptical that the problem could be due to dust or dirt under the hood. I thought I kept it reasonably clear with fairly frequent blasts with a powerful leaf blower, especially in dusty conditions. Also, the temp gauge never gets above normal.

Anyway, when I lifted the hood, there was a bit of superficial dust, but nothing out of the ordinary.........until I peered between the condenser and the adjacent radiators etc. There was something like a solid mat of grass debris in front and behind it!

I think part of the problem is the layer upon layer of structures at the front of the underhood area, all very close together - battery, intercooler, oil cooler, condenser radiator etc.

Anyway, using various methods, including most of the ones suggested, I managed to get it all clear and clean and, hey presto, the a/c works as it's meant to.:thumbsup:

So, now I just have to figure out how to stop the problem recurring in the first half hour of mowing in a dry field.

But, the most important thing ATM is to acknowledge the invaluable help given so freely and quickly on this forum. Please accept my genuine gratitude to everyone who replied and assisted. This is a top forum because it's frequented by top people.

Cheers and thanks
Tony

 

[greg_g]

That's fine as far as you went, But now you need to go around behind the tractor and look up. Above the rear window are two wing nuts holding a plastic panel. Under that panel you'll find the cabin filter. Under the filter you'll find the AC evaporator. Behind the evap is the heater core. Clean/replace as required. I think the manual says replace filter @ 50 hours.

If you don't trust the dealer, get a mate to help remove the cab roof so you can inspect the seal that runs around the entire circumference. When one man attempts to lift off the roof - especially the first time - seal damage is almost guaranteed. A new employee at my dealer learned that the hard way. Insufficient training and/or supervision cost them the otherwise unnecessary expense of a new seal. Outside air is meant to be drawn through the cabin filter only. But any gap in the roof seal will allow outside air to enter the ventilation system. Ambient air drawn in through a leaking seal will necessarily combine with conditioned air being generated through the evap/heater core, which in turn affects the cabin temperature. This would also be a good time to verify that the heat/AC control knobs inside the cab fully open/close their respective valves in the roof. If not, the adjustments are at the evap/heater end.

//greg//

 

[Tony M]

Thanks Greg, but I do clean the cabin filter fairly often. In fact, I had it replaced under warranty when it was apparent it was letting some dust bypass it as part of the rubber surround had delaminated.

Now that the a/c is working properly, I'll expect it to cool the cab. If it does, I'll leave it at that. There's really no reason to suspect a roof seal problem.

I do remember when the tractor was sitting at the dealership waiting for the radio to turn up, I asked why I couldn't have the tractor and get the radio put in later when it arrived. It was explained to me then that they always get two people to lift the roof when the radio goes in.

Cheers
Tony