RUUD RA16 Freezing Up At Coil

Pleated Air Filter (1-inch to 5-inch depending on cabinet)

The most common cause of coil icing is restricted airflow. If the filter is fouled with particulate matter, the volume of warm return air passing over the evaporator coil is insufficient to transfer heat to the refrigerant, causing the coil temperature to drop below freezing and turn condensate into ice.

Blower Motor Run Capacitor

The blower motor capacitor provides the necessary phase shift for the indoor fan motor to maintain rated RPM. If the capacitor's capacitance (microfarads) drifts out of tolerance, the motor will spin at a reduced speed or fail to start, resulting in inadequate heat exchange across the coil and subsequent flash-freezing of the fins.

Thermostatic Expansion Valve (TXV)

The RA16 utilizes a TXV to meter refrigerant flow based on heat load. If the internal diaphragm or sensing bulb fails, the valve may 'hunt' or remain in a restricted position, causing low suction pressure. According to the Pressure-Temperature relationship, low suction pressure results in a sub-freezing saturation temperature within the evaporator.