Your car or truck's AC system is under extreme pressure and the thermal expansion valve or orifice tube monitors the amount of pressure and the temperature of your A/C system. It calculates the precise amount of refrigerant that can safely go into the evaporator. A failing expansion valve or orifice tube often causes a vehicle's air conditioner to blow hot air.
Replace or Repair
- Expansion Valves: Too much refrigerant causes your evaporator to get too cold whereas too little refrigerant would result in inadequate cooling. The expansion valve is a complex valve that regulates refrigerant flow. This process of metering the refrigerant adjusts the flow according to the temperature of the refrigerant in the evaporator coil. Talk to one of the pro mechanics at My Mechanic, as this part can be replaced on its own and does not require the entire replacement of the AC assembly.
- Orifice Tubes: Unlike the expansion valve, the orifice tube is a simple fixed device with no moving parts. It therefore cannot vary the flow of refrigerant into the evaporator, but rather causes a permanent restriction in the system. However, like the expansion valve the orifice tube regulates refrigerant flow through the system and filters debris which may come through in its screen. Often fixing a "bad orifice tube" requires replacing the entire evaporator assembly.
