Valve Issues

Moisture under the valve moisture cap will make the valve intermittent. The system may work well then on occasion revert to cooling part of the cold plate. This is caused by ice freezing in the diaphragm, restricting it's motion. If your system has no cap or the cap is cracked or has been left off for any length of time moisture is then trapped in the valve body under the cap. To remove moisture from the valve body: Mark the adjuster barrel and count the turns counter clockwise. Remove the spring and the brass washer. Heat the valve with a hair drier to a warm temperature. (This is not to be too hot to touch.) Re-install the brass washer with the center divot in toward the diaphragm. Install the spring and then the barrel over it. Screw the adjuster barrel back to it's original position.


Valve Setting


Normally the valve is set using a pressure gauge connected to the compressor. The valve can be temperature set with a remote probe type thermometer attach the probe or clip it to the cold plate where the copper line from the expansion valve enters the cold plate. The valve should be adjusted to -2 to -5 degrees F. ( XPX units will be – 10 to –20 F.)

Valve Testing


The constant pressure expansion valve is a pressure regulator. To test it connect a low side gauge. With the compressor operating adjust the pressure up and down. Allow a minute or two for the pressure to settle. A good valve will easily adjust to a set pressure. A bad valve will not allow the pressure to drop when the adjustment knob is turned counterclockwise. A plugged valve will show very low pressure and will not raise the pressure when turned clockwise.