An orifice tube is a fixed restriction located between the condenser and evaporator that throttles refrigerant flow. It can be located anywhere in that section of the AC system. Special tools are required to remove and replace orifice tubes. Technician B is correct that if both sides of the orifice tube are hot, it could indicate the tube is clogged and causing a lack of cooling. Common manufacturers that may use orifice tube systems include GM, Ford, Chrysler and Toyota. Modern systems increasingly use variable displacement compressors and thermostatic expansion valves rather than fixed orifice tubes.