Ac system won’t equalize pressure.

[Stewartkyle44]

Hello, so I am at a loss. My tractors ac pressure (high/low) won’t equalize when charging. Low side goes up to 80-90psi while high side hovers around 50-80psi but won’t take any more freon. All proper steps have been taken per the service manual to evacuate and charge system. I have replaced compressor, dryer, and expansion valve. I have also blown out high and low side tube with compressed air to check for blockage. Not sure why system won’t equalize and take more freon to get the the right pressure which should be 206-213psi (high) 21-28psi (low). Any thought?

 

[K5lwq]

My first thought is compressor clutch is not engaging. Why was compressor replaced? Maybe give more information as to what was wrong and all the steps in order from the beginning.

 

[workinonit]

What freon is the system? It sounds like you aren't making up a low pressure cutoff switch but if you replaced the entire system then it could be anything. If you jump out the clutch will it come on so that you can get some additional freon in the system?

 

[Stewartkyle44]

@K5lwq compressor clutch is kicking on and off as it’s trying to pull in freon but won’t fully engage because the system isnt getting enough to trick the system to fully engage. It all started with the pressure relief valve on the back of the compressor blowing off sporadically. Slowly got worse and got tired of buying freon so I bought some of the main parts to tune it up since it’s a 2008 and probably needed it anyways.

 

[Stewartkyle44]

@workinonit the freon it calls for is R134a and that is what I am using. It seems the low pressure cutoff switch is working because the compressor clutch is disengaging because it’s at the threshold of to low of pressure to fully engage.

 

[workinonit]

The compressor needs to run long enough to get freon into the system. You were talking about the pressures equalizing, in order to get gas into the system you don't want the pressures equalized you need the low side to be much lower so the gas will enter the low side.

 

[Stewartkyle44]

@workinonit No matter how I introduce freon into the system the low side goes up to 80-90psi and the high side stops at 50-80psi. Shop manual says to introduce freon at the high side first with engine off the required amount 1.5lbs. Than close high side, start tractor, idle up to 2000rpms and than slowly introduce to the the low side until it reaches manufacturer recommended psi on high and low side during normal operating conditions.

 

[Harry in Ky]

@workinonit No matter how I introduce freon into the system the low side goes up to 80-90psi and the high side stops at 50-80psi. Shop manual says to introduce freon at the high side first with engine off the required amount 1.5lbs. Than close high side, start tractor, idle up to 2000rpms and than slowly introduce to the the low side until it reaches manufacturer recommended psi on high and low side during normal operating conditions.

Reading through your posts my first thought was you were charging the system with both valves on your gauge set open. This post confirms that you're not. My guess is you simply have a defective new component. Either the compressor is doing nothing or the expansion valve is open and not closing off flow. The valve being the most likely. The quality of replacement parts these days is dismal, and I'm not surprised by anything any more.

 

[Stewartkyle44]

@Harry in Ky That was my first thought. Bought the cheap ones first. Now I am on my second new compressor and expansion valve. Straight from manufacturer and still doing the same thing.

 

[LouNY]

What is your equalized pressure, system shut down and not ran for at least an hour and your ambient temp.