Tn75s air conditioning relay

[jammer48]

Everyone that's willing to learn or do things them self is in over there head at some point. It's how you get out of it. If your going to smack every project with your check book you will never learn anything.

OP AC in this and vehicles arnt very hard to work on. We just need a few key questions awnsered.

Is the compressor turning?

yes it is and the clutch was engaging

 

[jammer48]

With 2 cans added in the low pressure switch should have made and ran the compressor. If you added two cans and had 29 psi on both the low and high side the compressor had never kicked on. It just equalized in the system. The cans will get cold anytime you dispense gas from the can as the liquid is vaporizing and cooling the can.

Ok hmmm valid point so I suspect I have an obstruction? Perhaps the expansion valve? The compressor clutch definitely engaged.

 

[jammer48]

UPDATE So I read in one of the shop manuals I have for this tractor, that the expansion valve is located in the ceiling. LOL so I took the ceiling down and found all of my dye lying in a puddle of dirt. Today I am going to clean everything and attempt to pressurize the system and see if I get any results in terms of a leak.

There are two radiators in the ceiling. As I understand it one is for the heat and the other is the evaporator and the expansion valve is connected to the end of the evaporator.

 

[jammer48]

Everyone that's willing to learn or do things them self is in over there head at some point. It's how you get out of it. If your going to smack every project with your check book you will never learn anything.

OP AC in this and vehicles arnt very hard to work on. We just need a few key questions awnsered.

Thank you... my thoughts exactly.

 

[jammer48]

If it's anything like my NH TD95D, it's located on the evaporator which is above the headliner in the cab. I just had it replaced.

yes it is. I found it and a mess where a mouse had a nest in front of the evaporator

 

[jammer48]

2nd update!!!
I put freon in and touching the evaporator I had cold going in to touch and warm to touch coming out. Both sides of the drier were hot to touch and both sides of the condensor were hot to touch. guages showed 300 on the high side and 75 on the low side after freon. The static pressure, with the tractor off, was 100 on the low side and 200 on the high side. Finally, once the compressor clutch kicked on it never shut off or cycled. Any thoughts????

 

[LouNY]

High side seems abit high, maybe a touch to much freon.

From some of my literature;
"Before the vehicle is started, the static system pressure can be read.Pressure should be very nearly equal in both gauges. Actual pressure will depend on the type refrigerant and the ambient temperature and does not show if the system is properly charged. At 85 degrees Fahrenheit, R134A shows a pressure of around 90 pounds per square inch."


"Start the engine and turn on the air conditioner. Actual readings will vary according to ambient temperature. The low-side should be near 30 PSI at 90 degrees Fahrenheit or less. Pressure that is too much lower or higher shows there is a problem."


"On a properly working system, high-side pressure will be about twice the ambient temperature, plus 50 PSI. For instance, on a 90-degreeFahrenheit day, twice 90 is 180, plus 50 equals 230 PSI. This is not precise but close enough for the purposes of this article. Both pressures reading within these ranges means the system should produce a vent temperature in the mid, to low forties, with the engine idling."

 

[jammer48]

Thanks again Lou! I have that chart as well. I read that if looking for a restriction/obstruction you can actually feel the piping of your system and follow the temps and drops in temps for possible blockage. I am yet uncertain if I even have a blockage. I just came in because it was so hot outside. I will go back and take a staic opening pressure again and come back here with the readings.

 

[jammer48]

High side seems abit high, maybe a touch to much freon.
View attachment 3775644

From some of my literature;
"Before the vehicle is started, the static system pressure can be read.Pressure should be very nearly equal in both gauges. Actual pressure will depend on the type refrigerant and the ambient temperature and does not show if the system is properly charged. At 85 degrees Fahrenheit, R134A shows a pressure of around 90 pounds per square inch."


"Start the engine and turn on the air conditioner. Actual readings will vary according to ambient temperature. The low-side should be near 30 PSI at 90 degrees Fahrenheit or less. Pressure that is too much lower or higher shows there is a problem."


"On a properly working system, high-side pressure will be about twice the ambient temperature, plus 50 PSI. For instance, on a 90-degreeFahrenheit day, twice 90 is 180, plus 50 equals 230 PSI. This is not precise but close enough for the purposes of this article. Both pressures reading within these ranges means the system should produce a vent temperature in the mid, to low forties, with the engine idling."

"Start the engine and turn on the air conditioner. Actual readings will vary according to ambient temperature. The low-side should be near 30 PSI at 90 degrees Fahrenheit or less. Pressure that is too much lower or higher shows there is a problem."

My reply: What could the problem be? When I obtain the start up reading should all of my gauges be open?

 

[jammer48]

High side seems abit high, maybe a touch to much freon.
View attachment 3775644

From some of my literature;
"Before the vehicle is started, the static system pressure can be read.Pressure should be very nearly equal in both gauges. Actual pressure will depend on the type refrigerant and the ambient temperature and does not show if the system is properly charged. At 85 degrees Fahrenheit, R134A shows a pressure of around 90 pounds per square inch."


"Start the engine and turn on the air conditioner. Actual readings will vary according to ambient temperature. The low-side should be near 30 PSI at 90 degrees Fahrenheit or less. Pressure that is too much lower or higher shows there is a problem."


"On a properly working system, high-side pressure will be about twice the ambient temperature, plus 50 PSI. For instance, on a 90-degreeFahrenheit day, twice 90 is 180, plus 50 equals 230 PSI. This is not precise but close enough for the purposes of this article. Both pressures reading within these ranges means the system should produce a vent temperature in the mid, to low forties, with the engine idling."

first ambien temp is 92 currently measured with a thermometer next to guages. Second, with tractor running and low side (blue) open at strader valve and High side (RED) closed I have the following readings. 51 on low side (which then dropped to 30) and the High side (red) was 290

Again with the tractor running I opened both manifold valves and the low side went to 175 and the Red High side dropped to 190.