A/C Temperature?

[Tx Jim]

Check to be sure compressor belt is snug. If it were my tractor I'd install manual cutoff in the heater hoses as it get hot in Texas.

 

[RickB]

Check to be sure compressor belt is snug. If it were my tractor I'd install manual cutoff in the heater hoses as it get hot in Texas.

When the heater fights with the A/C, the heater ALWAYS wins!

Vent temp that is 25-30 degrees below ambient is probably going to be deemed 'normal' by any tractor manufacturer.

 

[Gary Fowler]

I would think vent temps should be about the same regardless of outside temps. I have used AC in vehicles when outside temps were 130F and the vent temps were always around 40F. Cab temperature varies with heat outside due to capacity of the AC but not the exhausting air temp from the vents.
My tractors AC cools at least that low winter or summer if I turn it all the way down. YOUR JD is definitely not cooling properly. That is one of the JD bragging rights about their cabs: The super cooling of the AC unit. You may need to go stand by the mechanic when they check and give him a Jethro Gibbs slab behind the head when he says 70F air is proper cooling. Maybe even bring your own thermometer and check some of the other tractors to see what they are doing.
I suspect it is a low Freon charge OR as said, heater valve is not closing properly, but with a brand new tractor, I would bet on lack of Freon first as the return line is icing up which isn't normal.

 

[The Fred]

I do a lot of A/C work on cars, trucks. We like to see low 40s coming from the vents. R-134 doesn't cool as well as the outlawed R12.

If you do not have the tools to check it properly (sounds like the dealer doesn't either) here's a quick way to tell. Engine idling or just above an idle, Have the fan on high and the settings on max cool, Place your hand on the lines at the compressor carefully of course. The high side (smaller line) should be warm (120 degrees) and the larger one (low side) should be low 40s (enough to really feel the difference. If it feels like a major difference in the two lines then the system is cooling but you have another problem up top such as:

Blocked evaporator fins maybe or the heater valve could be stuck on, you could look for a coolant valve near the engine and turn it off disabling the heater. Maybe the blend door is broken allowing hot air to mix with the cold air.

If you can differentiate between an actual refrigerant problem like not making the low side line (large one) cold or an air cooling problem (heater stuck on) for example it might help you to tell the dealer more info.

Good luck sounds like the dealer service advisor needs to be schooled because if his own rig only cooled down to 70 he would be screaming too!

Regards, Fred

 

[Texasmark]

Sweat all the way back to the compressor, after the unit has run for a time, getting the ambient (room/cab) temp in perspective is an indication that your freon level is adequate. Also if you have a sight glass on top of your expansion chamber/reservoir being clear with no bubbles and having the sweat back means you are full of freon. Course sweatback is temp humidity related and on hot dry days you won't see the same thing as cool wet days.....I mean you are condensing water vapor from the air on a cool surface.

30 degrees of temp difference between the two for both the evaporator (30 degrees cooler) and the condenser (30 degrees higher) is what I was taught in school. The system has a capacity that rides with the tide of the ambient conditions within the limits of the unit.....aka if the unit is overloaded by heat input or low/high freon it can't respond correctly. Normally once the system stabilizes and is not over taxed and the thermostat is in the coldest setting, it will maintain the 30 degree separation between input and output and continue to drop the ambient (room/cab) which drops the input and the output and etc. until it reaches it's cool limit and the stat shuts off the compressor. The stat doesn't change the cooling rate; the capacity of the system does that and if the compressor is engaged it has one rate. All the stat does is determine how long it will run at it's fixed rate.

Fan speed has a lot to do with it and if not high enough can allow icing and blockage on cooler days and once it starts icing it just gets worse. However, in a tractor cab in the summer that shouldn't be a problem. If it is, you have a problem with the system, usually over charged with freon which also drives up your pressures and can blow a seal in the system among other things.

One thing about cabs is the fact that engined/drive train heat and radiant heat from the sun, can be a big factor in cooling a cab. My rule of thumb for an average sized tractor, like my 65 hp is a 14,000 BIU's. A good size cooler for a 700 sq ft room in your home which is well insulated and most of the sun's rays are blocked, but for a tractor cab with 360 degree visibility, it can be a test by the environment for adequacy.

Agree that you check your heater valve and ensure it's closed.

Just because the tractor is new doesn't mean that your AC fill was adequate or that you don't have a leak somewhere, or that it wasn't over filled at the factory. Sounds to me like you have something wrong and as you said, now is the time to get it fixed.

You can do some checking on your own and might look up "AC wet and dry bulb measurements" on the www and get an idea for yourself as to how to test and what to expect.

Mark

 

[RickB]

I would think vent temps should be about the same regardless of outside temps.

That is unrealistic. Any A/C system is going to remove 'x' BTU's of energy from the treated air supply per hour. That translates more or less to 'x' degrees of temperature drop from whatever the ambient temp is, when the conditioned air is solely drawn from outside the cab, which also serves to pressurize the cab and help keep dust out. If that isn't enough, the option nearly always exists to recirculate all or part of the cooled air within the cab itself.

This is all separate and apart from the issue of whether the OP's system is performing as designed.

 

[94BULLITT]

Make sure the belt is tight.

 

[trook]

The service manager just responded to my message... on a Sunday! He stated the ac was blowing ice cold in their shop and it sounds like the water valve may not be closing. He will send a technician over tomorrow afternoon to check the cable adjustment on the valve.

 

[Cherokee140]

RUle of thumb I was taught; temperature from vents should be AT LEAST 30 degrees cooler than outside air temperature.

This.

That might not be enough to cool that greenhouse you sit in, but the air coming out should have a good drop.

 

[puckgrinder85]

Anything but measuring (as in evacuating and weighing) the charge is a guess on how full it is. The first thing we do with any a/c job is verify the content of the a/c system (as to not contaminate our machine) and then evacuate it to weigh it, unless something else is obviously wrong. This is coming from WI where the law on a/c are pretty strict on how you work on a/c. We actually have to be certified by the state to work on them legally.

 

[jenkinsph]

Anything but measuring (as in evacuating and weighing) the charge is a guess on how full it is. The first thing we do with any a/c job is verify the content of the a/c system (as to not contaminate our machine) and then evacuate it to weigh it, unless something else is obviously wrong. This is coming from WI where the law on a/c are pretty strict on how you work on a/c. We actually have to be certified by the state to work on them legally.

I agree with this, very common to overcharge a system without any real reason or understanding of the real problem. While most of us in the business are certified and have scales, recovery systems and the like most people do not. Without physically seeing the OP's tractor we can only guess where the problem is coming from and a new tractor should be repaired under warranty at any rate.

 

[jenkinsph]

trook,
Did you find out what the problem was yet?

 

[trook]

The service manager stated that when they had the tractor 2 weeks ago, the Freon was a little low on the gauges. So they recovered the Freon and charged it back to spec and leak checked the system. He said it was blowing ice cold in the shop. Since I am still having problems, he said it sounds like the water valve may not be closing (just as some of you have stated).

A tech came out Monday afternoon and determined that the water valve was indeed letting in too much warm water. After fully adjusting the valve, it was still letting in too much warm water. Therefore, they ordered parts and will hopefully install them Friday.

 

[trook]

The service manager stated a good symptom of the valve letting in too much warm water is that the ac will cool good initially but starts to diminish as the engine warms up. He was spot on. I held a thermometer to the vents and the air was blowing 45 degrees upon initially starting the tractor. However, a few minutes later, the air was blowing 70+ degrees.

 

[RedNeckRacin]

Where is that valve at trook?

 

[trook]

I'm not exactly sure, but it is apparently somewhere in the roof.

 

[Gary Fowler]

That is unrealistic. Any A/C system is going to remove 'x' BTU's of energy from the treated air supply per hour. That translates more or less to 'x' degrees of temperature drop from whatever the ambient temp is, when the conditioned air is solely drawn from outside the cab, which also serves to pressurize the cab and help keep dust out. If that isn't enough, the option nearly always exists to recirculate all or part of the cooled air within the cab itself.

This is all separate and apart from the issue of whether the OP's system is performing as designed.

I know a properly functioning AC unit will send out air from the vent that is much more than 30degrees below outside air temp. I used the AC vent to cool my soda when I was working in Saudi Arabia when the outside air was over 130F and it would cool the soda to refrigerator temp of around 40F. That is 90 degrees below outside air temp. While it wouldn't cool the truck itself much below 85F which I think is where everyone is getting the 30 degrees below ambient temps for the cooling capacity of the area in which it is installed.
Every AC unit I have ever seen recirculates some inside air, it doesn't pull 100% of the air from outside even if it is set to not recirculate.

 

[Tx Jim]

I'm not exactly sure, but it is apparently somewhere in the roof.

Correct water control valve on a JD 5075E is parts key #3

 

[jenkinsph]

I know a properly functioning AC unit will send out air from the vent that is much more than 30degrees below outside air temp. I used the AC vent to cool my soda when I was working in Saudi Arabia when the outside air was over 130F and it would cool the soda to refrigerator temp of around 40F. That is 90 degrees below outside air temp. While it wouldn't cool the truck itself much below 85F which I think is where everyone is getting the 30 degrees below ambient temps for the cooling capacity of the area in which it is installed.
Every AC unit I have ever seen recirculates some inside air, it doesn't pull 100% of the air from outside even if it is set to not recirculate.

Most AC systems will use a high percentage of recirculated air and a minimal amount of outside(or fresh) air. Typical would be 90% recirculated and 10% fresh air, that is enough to pressurize the cab. Lots of cheap residential systems don't have any provision for fresh air make up, it is recirculated air only.

 

[RickB]

I know a properly functioning AC unit will send out air from the vent that is much more than 30degrees below outside air temp. I used the AC vent to cool my soda when I was working in Saudi Arabia when the outside air was over 130F and it would cool the soda to refrigerator temp of around 40F. That is 90 degrees below outside air temp. While it wouldn't cool the truck itself much below 85F which I think is where everyone is getting the 30 degrees below ambient temps for the cooling capacity of the area in which it is installed.
Every AC unit I have ever seen recirculates some inside air, it doesn't pull 100% of the air from outside even if it is set to not recirculate.

Most AC systems will use a high percentage of recirculated air and a minimal amount of outside(or fresh) air. Typical would be 90% recirculated and 10% fresh air, that is enough to pressurize the cab. Lots of cheap residential systems don't have any provision for fresh air make up, it is recirculated air only.

My experience working on tractor A/C systems (Specifically Ford and New Holland) does not agree with the commentary regarding recirculation.