National average cost of a AC Expansion Valve Replacement for popular vehicles:
Avg. cost $124
What is an AC expansion valve and how does it work?
An AC expansion valve is a component of the air conditioning (AC) system. It is typically located near the AC evaporator core, on the firewall in the engine compartment or underneath the dashboard.
The expansion valve receives refrigerant (by way of the receiver/drier) at high pressure from the AC condenser. A tiny orifice in the expansion valve causes the refrigerant to expand rapidly as it passes through, reducing its pressure and absorbing large amounts of thermal energy (heat) from the evaporator in the process. Air blown by a fan through the cooled evaporator enters the passenger compartment.
The expansion valve is similar to a fixed “orifice tube” that serves the same function, except that the expansion valve is able to adjust the orifice size to accommodate varying conditions.
How do I know if my vehicle needs an AC expansion valve replaced?
The signs of a bad expansion valve can also point toward other problems with the AC system in your vehicle, such as a failed AC condenser or compressor. If you notice one or more of the following, the expansion valve could be bad
The air coming from the vents when the AC is engaged is warm
The AC compressor clutch does not engage or runs constantly
A warning light appears on your dashboard
The expansion valve body leaks oil
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The procedure to replace an AC expansion valve replacement will vary depending on your specific vehicle year, make, and model. A technician will first need to evacuate the AC system using a special machine to capture the refrigerant. (It is illegal to vent AC refrigerants into the atmosphere, and only technicians specially certified may service air conditioning systems). Once the system is empty, a technician will generally take the following steps to replace an expansion valve
Remove any components that block access to the expansion valve
Disconnect the 2-4 refrigerant lines connected to the valve housing
Remove the valve
Install the new valve with fresh o-rings
Connect all refrigerant lines
Using the AC machine, evacuate the system of all air and moisture
Allow the system to remain under vacuum for up to 30 minutes
Charge the system with an amount of refrigerant specific to your vehicle
Start your engine and test the system to verify the repair
Vehicles where the expansion valve is located inside the passenger compartment will also require that the technician remove lower sections of the dashboard for access and might require removal of the heat-exchange box where the evaporator is mounted. Some vehicle manufacturers may require that the AC receiver/drier be replaced whenever the AC system is opened and exposed to the atmosphere.
OTHER QUESTIONS CUSTOMERS ASK
What happens if an air conditioning expansion valve is stuck open?
One of the functions of an AC expansion valve is to adjust the size of its orifice to meet the demands of the AC system under varying conditions. If the valve sticks in the open position, excessive refrigerant will flow through the orifice, effectively dropping the pressure in the system too low for the conditions. This can cause the evaporator to drop below freezing. Ice or frost can form on the evaporator coils and fins and on the expansion valve housing. This will ultimately lead to airflow blockage through the evaporator and a reduction in the performance of your AC system.
Can the expansion valve leak?
An AC expansion valve can develop a leak. If it does, it will cause the refrigerant pressure to drop and decrease the efficiency of the AC system. The air coming from the vents will no longer blow cold air.
What causes an AC expansion valve to fail?
Contaminants in the refrigerant - moisture or debris from a failing AC compressor - can clog up an expansion valve. Some AC expansion valves include a screen that can catch contaminants more readily and block the flow of refrigerant. A system that is overcharged with refrigerant can also lead to expansion valve failure.
What parts are related to a AC Expansion Valve Replacement?