A/C Temperature?

[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.