An orifice is a small, precisely sized hole inside a metering device that regulates the flow of refrigerant into the Evaporator Coil. In many Mobile Home AC Condensers, a "fixed orifice" is used because it is reliable and inexpensive. However, if the orifice is the wrong size for your unit's tonnage, it will cause the coil to freeze or the compressor to overheat. You can find replacement pistons and orifices in our Parts department for fine-tuning your system's performance. Our ACIq coils come with pre-installed orifices designed for specific SEER2 ratings. It is a tiny part that has a massive impact on the efficiency of the refrigeration cycle. Ensuring the orifice is clean and free of debris is a key part of any professional Evacuation and startup. It is the mechanical gateway that turns high-pressure liquid into cooling gas.