# JD 7200 air conditioning issues



## Trotwood2955

'95 model, not the new R series. Baled with it 3 days in a row last week, 90+ degrees, high humidity, and on the second day the air conditioning started acting up. I had been baling for a couple hours when I noticed the cab wasn't staying cool. The vents were hardly putting out any air, and what little bit was coming out felt warm. I cranked it up to the highest fan speed and it started to blow cold (or colder anyway) air. After leaving it on the high setting for a few minutes I would cut it back to the second or third notch and it seemed to continue blowing semi-cold air like it should, just at a lower rate. But, after 10 minutes or so it would be back to blowing warmer air or not hardly blowing at all. I would repeat the cycle (putting on the highest setting for a few minutes) and that would cool things down again. I could have just left it on the high setting I guess, but something still seems to be wrong because I've run this tractor for 5 years now and hardly ever have to go up past the second notch on fan speed, at most to the third, but never the highest setting to keep it ice cold. When I would bump it up to the high speed I was also getting a smell in the cab that almost seemed like anti-freeze. Would this be freon? Does it sound like I have something plugged up somewhere, or the system needs to be re-charged, or what? Thanks for any help.


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## Tx Jim

Possibly needs coolant but attaching gauges & looking at the pressures is the only way to accurately determine. Is radiator,condenser & cab filter CLEAN?


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## Bonfire

My first thought is the evaporator coil is freezing up. Are you getting enough air across it?

Make sure the cab filters are clean. Follow the intake duct work all the way to the end where it's pulling fresh air. Make sure there is no obstruction.

Are the condensate lines draining? If they are plugged up or drain slow, condensate maybe splashing up onto the evaporator coil and freezing it up.


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## Trotwood2955

I think everything is clean, but I'll check it over again tonight.

I'll check the drain lines, not that I was paying too much attention to them the other day, but now that you mention it I don't remember seeing them draining as much as usual...but could just be my imagination.


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## ARD Farm

The drain lines where the come out under the cab (on any tractor for that matter) tend to get clogged up at the end. Stick a small screwdeiver up there and see if they are clogged and open them up if necessary. I bet the evaporator is freezing up...

Easy way to tell is if the compressor starts short cycling in the field.


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## Trotwood2955

What exactly do you mean by "short cycling"?


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## MScowman

I'd check the drain line as well, If you have dirt dobbers like we do.


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## luke strawwalker

Trotwood2955 said:


> '95 model, not the new R series. Baled with it 3 days in a row last week, 90+ degrees, high humidity, and on the second day the air conditioning started acting up. I had been baling for a couple hours when I noticed the cab wasn't staying cool. The vents were hardly putting out any air, and what little bit was coming out felt warm. I cranked it up to the highest fan speed and it started to blow cold (or colder anyway) air. After leaving it on the high setting for a few minutes I would cut it back to the second or third notch and it seemed to continue blowing semi-cold air like it should, just at a lower rate. But, after 10 minutes or so it would be back to blowing warmer air or not hardly blowing at all. I would repeat the cycle (putting on the highest setting for a few minutes) and that would cool things down again. I could have just left it on the high setting I guess, but something still seems to be wrong because I've run this tractor for 5 years now and hardly ever have to go up past the second notch on fan speed, at most to the third, but never the highest setting to keep it ice cold. When I would bump it up to the high speed I was also getting a smell in the cab that almost seemed like anti-freeze. Would this be freon? Does it sound like I have something plugged up somewhere, or the system needs to be re-charged, or what? Thanks for any help.


Usually if it quits blowing on a lower fan speed and gets warm with little/no air coming out the vents, it may be freezing up the evaporator coil... They can get cold enough to frost over and without enough airflow to keep them from icing up, they can get covered with a layer of ice that blocks off air from moving through them, forcing it around the coil. I suspect this is what's happening since you said it does it cooler when you turn the fan on high. Moving more air melts the ice off the coils and lets the air flow through it instead of around it and cools things down. Make sure your drains are clear to drip condensate out on the ground and that your air filters (if applicable) aren't clogged or dirty-- it's surprising how much airflow can be reduced by a dirty filter-- enough to allow coils to freeze up at low fan speeds.

You won't really know what's going on until you hook up a set of manifold guages to your system... If you don't have a set and don't know anybody with a set, you CAN get one of those cans of freon from the auto parts store that has a small low-pressure side guage installed on the can along with the fill hose... Hook it up and run the system with it on full fan speed and the door open, at about half throttle to full throttle... your low-side pressure should be in the indicated range unless something's wrong... usually if they're working but the low side pressure is too low, they just need some freon... put some in until you get the correct low side pressure. Of course, if there's a compressor problem or other system problem (clogged orifice tube or expansion valve or other malfunction) the pressure could be too low even with plenty of freon-- that's where a manifold guage that reads both low and high side pressure is invaluable.

Freon is odorless, other than the oil in the freon, which sorta smells like the old light machine oil, or "3 in 1 oil"... If you were smelling freon oil, the system would have lost all the refrigerant pressure and wouldn't work at all. If you're smelling antifreeze, most likely you have a heater core leak or something-- could be leaking hot water or hot steam, which would definitely reduce the efficiency of the AC system, which is meant to cool ambient air, not 190-200 degree steam or leaked coolant. Might be a pinhole leak or something, as a serious leak would probably be pretty evident pretty quick, obviously...

Later and best of luck!

OL JR


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## luke strawwalker

Trotwood2955 said:


> What exactly do you mean by "short cycling"?


Short cycling is the compressor turning on and off rapidly-- typically the compressor "cycles" on and off, but it usually turns on for at least 30 seconds to a minute or so, then turns off for anywhere from about, oh, 10-15 seconds to a half minute or so... (highly dependent on temperature). When the compressor is "short cycling" it will turn on for maybe 5-10 seconds or so, and then shut off for 5-10 seconds or so (again, dependent on temperature).

The compressor compresses the slightly cool freon gas coming out of the evaporator coil in the tractor cab AC unit. This freon gas has absorbed the heat in the cab air flowing through it to boil the freon into a gas, which of course takes heat. The compressor squeezes this gas to a high pressure and pumps it through the condenser coil in front of the radiator, where it gives off the heat it absorbed in the cab (plus the heat added by compressing the freon gas in the compressor) and by releasing that heat, it then turns back into hot liquid freon under high pressure... This liquid freon then flows (usually through a filter/dryer that keeps the system clean) through hoses back close to the evaporator, where it flows through either an expansion valve (older systems,usually) or an expansion tube that has a small orifice tube in it-- essentially a small tubular "spray nozzle" that restricts the flow of freon through it... this keeps the high side pressure high enough to force the hot freon gas to condense to a liquid in the condenser coil (as it doesn't get cool enough to condense to liquid without the extra pressure) and as the liquid freon sprays through either the expansion valve (which is usually operated by a pressure bulb that senses the temperature of the evaporator coil) or through the orifice tube, its pressure drops to the low side pressure, and the freon begins to rapidly boil off inside the evaporator coil, which takes heat to make it boil, making the evaporator coil get freezing cold... The freon boils to gas and flows out of the evaporator back to the compressor to repeat the cycle.

If the evaporator coil gets TOO cold, like if there's not enough airflow to keep "warming it up" with warm air from the cab, which it cools and blows out onto the operator, the coil can get below the freezing temperature of water, and will frost up or freeze solid with ice from moisture in the air. Once it's blocked up with ice, it won't let hardly ANY air flow through it, and since the air cools by flowing THROUGH the coil rather than AROUND it, the air will stay pretty warm going around it. This also lowers the amount of heat that the evaporator coil has available to boil off the freon, so the system pressure gets screwed up. Allowing the coil to thaw and keeping the airflow sufficient (high fan speed, cleaning the filters, moving anything that might obstruct the airflow into the system (bag sucked up against the blower intake, leaves, mouse nest, junk, etc.) is usually all it takes to fix it. A frozen evaporator coil will also "short cycle" quite a bit. The compressor usually has a pressure switch that senses the low side pressure and turns the compressor clutch off and on to turn the compressor off and on. If the evaporator gets too cold, the liquid freon only boils very very slowly, reducing the amount of freon gas pressure on the low pressure side as the compressor continues sucking in freon gas from the evaporator through the hoses, lowering the pressure, and the switch opens and shuts the compressor off. The freon will continue to boil in the evaporator as it slowly absorbs heat, which then raises the freon gas pressure on the low pressure side of the system, until the pressure switch is closed by the pressure and turns the compressor back on-- this is what causes the compressor to "cycle". In hot conditions, there's SO much heat available to the evaporator coil that the freon boils very rapidly and easily, and the low side pressure can remain high enough that the compressor runs continuously, with little/no cycling... Modern systems also use a high pressure side pressure switch to prevent the compressor from overpressurizing the system and blowing freon out the relief valve. Pressures on both sides of the system are highly linked to the ambient temperature-- the hotter it is, the higher the pressure. The hotter it is, the more pressure it takes to force the freon to change from a hot compressed gas to a warm (hot) liquid freon, forcing it to give up its heat to the airflow through the condenser coil in front of the radiator... and of course good airflow to the condenser coil is also essential for proper AC system functioning...

Later and good luck! OL JR


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## mlappin

Not familiar with John Deere A/C, but did they do away with the sight glass on the receiver dryer? If it still has the sight glass and if you see any bubbles in the glass wit the compressor running and the ambient air over 72 degrees then it's low on freon. Sounds more like the evaporator is freezing over though, a bad thermostat can also cause a evaporator to freeze over as well. Make sure everything is clean to get max air flow thru the evap, if it still acts up after everything is clean I'd be betting on a bad thermostat, I've also had the probe come out of the evaporator before as well which also causes freeze up.


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## Tx Jim

I was thinking a few bubbles in sight glass with 134A is OK. When I check/add coolant I really never look a sight glass just go by gauges.


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## Rodney R

Add another vote for the evaporator freezing up. You said the air coming out was "colder" - did you ever put a valve in it to shut off the hot water for the heater? We have 2 7400's and both of them never got cool (!) in the cab, yet the 7210 blew icicles...... Installed a shut off valve on a heater hose and viola!

Rodney


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## Bazooka

I've seen those filters behind the seat so clogged up with lint and dust from the cab floor that they would affect performance, and if they have a pin hole in them they put they debris directly on the evaporator and start plugging the fins. You may be able to turn on your heater just a bit and see if it affects the evaporator, if it is freezing up at the evaporator, the warm air from the heater core next to it may keep it melted and help determine if you have the unenviable job of removing the seat.


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## Trotwood2955

Thanks everybody for the replies. They have definitely helped me understand the overall system better.

I was looking over everything last night. The radiator and condensor were dirtier than I thought so I am cleaning them out good. Certainly not totally clogged, but still dirtier than I expected. I also need to pull the cab filters and check them. I cleaned them out a few months ago but I know they could be filthy again.

The one drain tube was clear. But I couldn't find a second one, which I thought was odd since all our other tractors have 2 and the parts diagram online is showing two. So I don't know if it has gotten pulled off or pushed up into a crack somewhere and that could be causing a backup or a clog. Need to look it over better tonight, I could have just missed it as I ran out of time last night.

I dont have a set of guages but know someone who does. I'll see if I get them to come and test everything with them.

This particular system does not have a sight glass on the receiver dryer.

When you mention it could be the thermostat going bad, you mean the regular thermostat out towards the radiator, right? Not a thermostat or somethign within the A/C unit?

I have never installed a shutoff valve for the hot water side. Might be something worth looking into, but I don't think that is the root issue here, becasue before now the A/C has always blown very cold in this tractor.

I'm pretty sure it was anti-freeze I was smelling at times the other day. It wasn't all the time, only for brief periods, usually when I had it running on high speed. I'd like to get everything cleaned up good and see what that does for things before I start tearing into other stuff.

I'm really hoping I don't have to remove the seat/floor to get to the actual unit. Until I started looking it over I never even realized the unit was where it is under the cab. Looks like it will be even more fun to fool with than the older tractors with the units in the cab roof.


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## Tx Jim

It doesn't take much heater valve leakage to affect AC cooling ability. I highly recommend installing manual heater hose shut valves such as I installed on my 4255 back in the mid 90's. Thermostat referred to is AC thermostat that controls compressor cycling.


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## mlappin

Tx Jim said:


> I was thinking a few bubbles in sight glass with 134A is OK. When I check/add coolant I really never look a sight glass just go by gauges.


Every system except one I've worked on if properly evacuated will react just like R12, when full no bubbles. Have one system that works very well, is full according to my scales, but still shows a stray bubble.


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## Tx Jim

mlappin said:


> Every system except one I've worked on if properly evacuated will react just like R12, when full no bubbles. Have one system that works very well, is full according to my scales, but still shows a stray bubble.


My 4255 cools better on 134A than it ever did on R12.


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## mlappin

Tx Jim said:


> My 4255 cools better on 134A than it ever did on R12.


I've had a few in the past like that, our MF 4880 never did work real well. Last major overhaul I completely flushed the system and started over, was overloaded with oil. Took gallons and gallons of flush to get all the lines, condensor and evaporator clean. Thats why I hate the leak stop products, all contain at least a little oil and a system thats overloaded with oil is almost worse than a system thats a little low on oil.


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## Trotwood2955

Where is the A/C thermostat located? If it is what I am seeing on the parts diagram online, it looks like it is located under the cab near the main unit (but hard to tell in the diagram).

And on installing that manual heater hose shutoff, where would that go? And is this a valve or something I would need to get from the dealer or are we talking just a generic valve for an a/c system?

Sorry for the simple questions, just trying to make sure I understand it all!


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## Tx Jim

Heater hose valve can be installed anywhere that's convenient in either or both heater hoses. Cutoff should be available on line or good auto parts store. Yes thermostat is under seat.


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## Tx Jim

nt


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## Trotwood2955

Thanks for the info.


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## Rodney R

I used a couple vice grips to pinch a heater hose on the side of the engine, cut the hose between them, and used a hose barb on each end of a ball valve. But if the A/C was cooling fine before this issue, then I would look for another issue.

Rodney


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## Trotwood2955

But if I was actually getting a wiff of anti-freeze every once in awhile, caused by some type of heater valve leak, if I did the simple thing of installing a shutoff valve on a heater hose wouldn't that essentially "fix" the problem for now? And avoid needing to remove the seat and get into the a/c unit itself? At least until things are a little less busy. Again, assuming that might be part of the problem, I still haven't gotten anybody out with gauges yet to check things out yet.


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## luke strawwalker

Trotwood2955 said:


> But if I was actually getting a wiff of anti-freeze every once in awhile, caused by some type of heater valve leak, if I did the simple thing of installing a shutoff valve on a heater hose wouldn't that essentially "fix" the problem for now? And avoid needing to remove the seat and get into the a/c unit itself? At least until things are a little less busy. Again, assuming that might be part of the problem, I still haven't gotten anybody out with gauges yet to check things out yet.


Basically, yes, if you install a valve on BOTH hoses. Agree with someone above that said "pinch the hose w/ vice grips, cut between them, install a gate valve or ball valve with hose barbs on either side and hose clamps. DO it wherever it's convenient for you to get to them to turn them on in the fall and off in the spring...

Our old school buses I used to drive had a regular gate valve down by the floor plumbed into the system... at certain times of the year, you'd turn the thing on in the morning and off in the afternoon-- cool enough to need heat in the morning, and warm enough you didn't like the extra warmth coming up out of the core in the afternoon (with the fan off).

Later! OL JR


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