Rheem RARL-JEC Installation Instructions - Page 45

THERMOSTATIC EXPANSION VALVES SYMPTOMS Superheat is low to normal with low suction pressure POSSIBLE CAUSE Unequal evaporator circuit loading Low load or airflow entering evaporator coil Superheat and suction pressure fluctuate (valve is hunting) Expansion valve is oversized Sensing bulb is affected by liquid refrigerant or refrigerant oil flowing through suction line Unequal refrigerant flow through evaporator circuits Valve does not regulate at all Improper superheat adjustment (only possible with TEV having superheat adjustment) Moisture freezing and partially blocking TEV External equalizer line not connected or line plugged Sensing bulb lost its operating charge Valve body damaged during soldering or by improper installation CHECK OR REMEDIES Ensure air flow is equally distributed through evaporator Check for blocked distributor tubes Ensure blower is moving proper air CFM Remove/Correct any air flow restriction Install correct TEV Relocate sensing bulb in another position around the circumference of the suction line Ensure sensing bulb is located properly Check for blocked distributor tubes Replace TEV or adjust superheat Recover refrigerant, change filterdrier, evacuate system and recharge Connect equalizer line in proper location, or remove any blockage Replace TEV Replace TEV 45