In an air conditioning unit, the expansion valve is responsible for changing the pressure inside the HVAC system, allowing the refrigerant to transform from its liquid state into a gas in the evaporator coils. When the expansion valve malfunctions, it can cause problems with the AC unit, such as inadequate cooling, or short-cycling.

Diagnosing Faulty AC Expansion Valve

#1 Air Conditioner Not Blowing Cold Air

The expansion valve should allow the liquid refrigerant flow to transform into its gaseous state in the evaporator, thus enabling your AC system to blow cold air into the room. If your air conditioner is blowing warm air instead of cool air, there are a couple of factors that can cause your AC unit to malfunction.

One of the factors is a blocked, cracked, or otherwise faulty expansion valve. Because the valve is not working properly, the liquid refrigerant is having difficulties cooling the air as it struggles to transform into a gas.

#2 Inadequate Air Flow

Inadequate or inconsistent airflow can also be caused by a faulty expansion valve. As the valve is damaged, it malfunctions, causing an irregular flow of refrigerant to pass through the coils. When this happens, the AC unit may not circulate enough refrigerant, and may not blow cool air into the room consistently.

#3 Frosted Air Conditioning System

A frosted air conditioning system is often caused by a dirty air filter, dirty coils, or refrigerant leaks, but it can also be caused by a faulty expansion valve as the valve causes the refrigerant to stay stagnant. This cools the air within the unit, freezing vapor in the air.

How to Replace AC Expansion Valve: A Step-by-step Guide

It is not recommended to repair or replace the expansion valve yourself as this air conditioning component deals with refrigerant, which can be hazardous when inhaled or ingested. Take proper precautions when handling refrigerant, and contact one of our HVAC technicians in Luce Aircon instead to tackle the repairs for you.

Step 1: Shut Off the Air Conditioner

Shut off the air conditioner at the first sign of a problem, and cut the power source. This will make it safer for you to inspect the unit without getting an electrical shock, or a mechanical mishap. Make sure your AC system is completely powered down before you start repairs.

Step 2: Open the Air Conditioner, and Locate the Expansion Valve

Remove the housing of your indoor unit, and locate the expansion valve. The expansion valve connects the condenser to the inlet of the evaporator coil, so expansion valves are typically located between the two coils.

Step 3: Lock the Refrigerant Lines

Lock the refrigerant lines to prevent coolant from escaping. Use gauges and valves to lock the refrigerant lines while you work on the thermal expansion valve. This will help keep you safe from inhaling or coming into contact with coolant.

Step 4: Dismantle the Expansion Valve, Secure the New Valve

Dismantle the expansion valve by disconnecting it from the evaporator coil. Carefully remove the old, faulty valve, and set it aside. Take your new expansion valve, and secure it in place. Connect the new valve to the coils, and ensure that the connections are tight and secured.

Step 6: Close Up, and Test

Remove the locks from the refrigerant lines, and close up the air conditioner. Restore the power to your unit, and power on your AC system to test the repairs. If the repairs are done correctly, then your AC unit should run smoothly with no problems or issues.

AC Expansion Valve Replacement Cost

The cost to replace a failing expansion valve runs around $400 per unit, but the average range of the repair costs around $300 to $700, depending on the type of air conditioner you have. Labor costs may drive the price higher.

Where to Buy Replacement Expansion Valves

#1 Hardware Stores

Hardware stores often carry different valves and components, including expansion valves. However, not all expansion valves are fit for air conditioners, so you will need to take note of the model of your air conditioner, and the type of expansion valve it uses to find the exact item you're looking for.

#2 Luce Aircon

At Luce Aircon, we make owning and operating HVAC systems a breeze with our purchasing services. Our team has decades of experience in all things air conditioner, so you can be assured we'll find the exact part you need to repair your unit, and tackle the repairs for you as well!

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Give us a call, and a description of your AC problem, and we'll get to fixing up your air conditioner!