Expansion Valve: Testing and Inspection

1. Connect manifold gauge set.
2. Run engine at fast idle and check low pressure gauge reading.
a. Gauge readings below 7 psi may be caused by moisture freezing in the expansion valve orifice, a clogged valve, or by gas leakage from capillary tube or bulb. Check or replace expansion valve or receiver/drier.
b. Gauge readings above 70 psi may be caused by excessive opening of expansion valve orifice due to a loose remote bulb holder or a defective expansion valve. Retighten or replace bulb holder or replace expansion valve.