Clogged Orifice Tube

A fixed orifice tube contains a small brass tube of a fixed diameter encased in a plastic case. The case contains a debris-catching filter at each end. It's located between the condenser and the evaporator core. It's usually easy to locate because many manufacturers crimp the line that holds the orifice, preventing it from traveling down the tube toward the evaporator core.

The orifice tube can become restricted and clogged with debris. A clogged orifice tube is typically caused by compressor failure. Little metal and aluminum shrapnel will be found in the tube's screen filter when this happens. If the filter is filled with white or brownish debris, the desiccant bag in the accumulator has broken. This sends desiccant throughout the system. This restriction will cause high high side system pressures. Restrictions result in frost forming around the restricted area.