Expansion Valve: Testing and Inspection

The expansion valve can fail in three different positions (open, closed, and restricted).

IN AND OPEN POSITION
This will result in a noisy compressor or no cooling. The cause can be a broken spring, broken ball or excessive moisture in the A/C system. If the spring and ball are found to be defective, replace the expansion valve. If excessive moisture is found in the A/C system, recycle the refrigerant.

IN A CLOSED POSITION
There will be little or no suction pressure and no cooling. This may be caused by a failed power dome or excessive moisture in the A/C system. If the power dome on the expansion valve is found to be defective, replace the expansion valve. If excessive moisture is found recycle the refrigerant.

A RESTRICTED ORIFICE
There will be low suction pressure and no cooling. This may be caused by debris in the refrigerant system. If debris in the system is believed to be the cause, recycle the refrigerant and replace the expansion valve and the receiver drier.