What is the Expansion Valve (Orifice Tube)?
The air conditioning system in your vehicle depends on the refrigerant that circulates in the A/C system. In particular, the evaporator core inside the passenger compartment needs a specific, metered amount of refrigerant in order to efficiently cool the interior. The expansion valve, also known as an orifice tube in some designs, controls the pressure of refrigerant that enters the evaporator. The tube is also where liquid refrigerant under pressure converts to a gaseous form. The gaseous refrigerant absorbs heat from air passing through the evaporator core and carries it to the condenser where the heat is removed.
In a situation where the orifice tube is either blocked or stuck open, the air conditioning will not cool properly. Too much refrigerant will cause frost on the core and prevent air from passing through to cool the air temperature. Too little refrigerant passing through the evaporator means not enough heat is absorbed and the interior is insufficiently cooled. In either situation, you may need to replace the expansion valve/orifice tube.
Facts to Note:
Air conditioning work needs to be completed by a trained and licensed professional in nearly all circumstances because refrigerants are controlled substances.
It is possible for the expansion valve to become blocked by excessive moisture in the air conditioning system, which would indicate a receiver/drier problem.
How to Fix:
The AC refrigerant is removed from the system
The faulty expansion valve is removed
The new expansion valve is fixed
The a/c system is recharged with refrigerant
The a/c system is tested for leaks and correct operation
Whenever air conditioning repairs or refrigerant recharges are done, have the expansion valve examined for proper operation. If the expansion valve is not opening or closing properly, you may need one of your expert technicians to change the expansion valve or orifice tube.
Common signs indicating you may need to change the Expansion Valve (Orifice Tube):
Air conditioning doesn’t cool sufficiently
Air conditioning expansion valve is frosty but the air conditioning isn’t blowing cold air
Importance of this service:
Air conditioning is a comfort item in a vehicle, not a safety problem. However, the air conditioning also removes moisture in the air for the defrost setting to clear your windows. If the air conditioning is not working correctly, your vision may be impaired in humid or very cold weather.