What Is a Schrader Valve and Why Does It Matter for Your HVAC?

Perhaps you’ve never heard of it in relation to cooling your home, but a Schrader valve in an HVAC system keeps refrigerant inside the air conditioner. If you’ve ever put air in a bike tire or heard the whoosh of air coming out of a car tire, you’ve seen just how well a Schrader valve works. Learn how it functions and how to maintain it in this informational guide. 

What Is a Schrader Valve?

A Schrader valve is common in U.S.-manufactured air conditioner units, motor vehicles, and other powered devices. What sets them apart is the valve core, or shell, and a pin or spring that sits inside and keeps the valve closed until you need to manually open it with a tool. Pressure alone cannot open the valve to release air or refrigerant.

You may occasionally hear a technician refer to a Schrader valve as a service valve or core valve. The Schrader company originally produced the valve in 1891. 

What Is a Schrader Valve Used for in HVAC?

The Schrader valve is convenient in an air conditioner because the valve stays closed in a high-pressure environment. Its two-part build makes a Schrader valve the ideal locking mechanism for machines that occasionally need to be serviced or taken apart, which is definitely the case for HVAC units. 

In HVAC, a Schrader valve uses a shell and a pin or spring to keep air pressure in or out. The valve also keeps air out of the refrigerant lines in AC units. The two main components of the Schrader valve are the outer cover, also known as a threaded hollow shell, and the poppet valve, which sits inside the hollow shell. 

A professional HVAC specialist (or handy homeowner) can use a Schrader removal tool to add or remove refrigerants, for example. But once servicing is complete and the device is on, the valve won't open even when the unit runs at maximum capacity.

Are AC Schrader Valves Universal?

The valve core and pin or spring size on refrigeration Schrader valves are generally the same, which makes it easier for a professional to service them using a Schrader removal tool. However, the size of a Schrader valve may vary depending on the object. For example, a window air conditioner may not have the same size Schrader valve as a truck tire. 

You can buy Schrader core tools for different devices. So if you buy a general removal tool for an air conditioner, it should fit the one in your unit. But there's a chance you could need a different one for a car tire or bike tire.

AC Schrader Valve vs. Schrader Bike Valve

A Schrader AC valve and a tire valve are similar, but they’re not exactly the same. While the mechanism that maintains air pressure is the same, a Schrader valve for air conditioning units keeps air out of the refrigerant lines. Bike or car tire valves use a Schrader valve to keep air in and maintain tire pressure. Schrader valves for AC units are also typically designed to withstand colder temperatures.

Maintaining an AC Schrader Valve

First and foremost, keep the Schrader valves on your air conditioner clean. They’re generally located on the back or inside the cover and near the AC lines.

When servicing your unit, use a towel to wipe away dirt and grime around the area and on the valve's threads. Your AC Schrader valve should also come with a cap for covering the threads. Keep the cap on, and keep it clean to prevent wear and tear that could lead to leaks.

Fixing or replacing a Schrader valve is a common service for HVAC units. HVAC repairs cost around $350, but you may pay more if there’s damage due to negligence or lack of HVAC maintenance.

When to Get a Schrader Valve Replacement

One of the main signs that your Schrader valve needs servicing is if refrigerant is leaking from your air conditioner. If this is the case, you may need to clean or replace the valve. Unless you're savvy with HVAC units, this is most likely a job best left to a local HVAC technician. Tinkering with an AC unit may lead to further damage and more expensive repairs.