What You Need To Know About The A/C Expansion Valve

Your car’s air conditioning system is designed to provide comfort of every trip you take in your prized ride. As a car owner, it is recommended that you understand how the various components function, e.g. the A/C expansion valve. Otherwise, you may end up having to deal with expensive car repair costs. Let’s find out more about A/C expansion valves:


How does an A/C Expansion Valve Work?

An expansion valve is designed to remove pressure from the liquid refrigerant in an A/C system. When expansion in enabled, the refrigerant can be converted into vapor inside the evaporator. Next, an expansion valve also controls the refrigerant flow. This process is also known as metering. Inside a valve, one can find a moveable rod that moves upwards and downwards. The rod is designed to keep the passageway inside opened or closed, i.e. allowing and preventing refrigerant from entering. This type of control is important in an A/C system because it ensures the comfort of your passengers and you when driving on a hot day.

Understanding the Difference Between Expansion Valves and Orifice Tubes

Orifice is a term that describes a hole of a predetermined size. An orifice tube is basically a plastic component that features a brass jet on one side and a mesh screen on the other. The size of the hole must be accurately calculated to ensure the right amount of refrigerant is metered into the evaporator.

On the other hand, A/C expansion valves feature moving parts. The amount of refrigerant in the evaporator can change on the fly. This is done to maximize the coldest possible temperature without resulting in freezing. If the evaporator freezes, the gaseous pressure in the tube will decrease. This causes the expansion valve to close.

What are the Common A/C Expansion Valve Problems?

You will notice your A/C system acting weirdly if the expansion valve fails. Some of the symptoms include:

  • A/C vents blowing out warm air
  • Frost starts to form on the vents or the A/C evaporator
  • The A/C compressor is constantly running

To further elaborate on the third symptom, it indicates that the expansion valve is stuck and cannot fully open. The compressor is forced to continue pumping refrigerant into the A/C system, even when the interior is already cold.

In any case, it is recommended that you send your vehicle to an A/C specialist to have it checked and repaired. The valves are often located deep within your car’s A/C system. Finding it is not as simple as refilling gas.

Is Replacing an A/C Expansion Valve Difficult?

The degree of difficulty in facilitating A/C expansion valve replacement varies greatly between models, makes, and year. You may need to evacuate the system before the procedure and recharge it afterward. It is possible to undertake a D.I.Y project if you have the right air-conditioning tools, e.g. an evacuation pump, a manifold gauge set, and etc. Oftentimes, these useful tools are bundled in a convenient package. If not, it is better to consult auto repair shops and not make things worse on your own.