An unloader valve is one of the most critical parts of an air compressor because it releases the trapped air in the tank after the motor stops running, allowing the system to restart smoothly. A malfunctioning unloader valve is among the most common issues that prevent a compressor from operating correctly. When the air cannot escape from the tank, the built-up pressure will often hinder the unit’s ability to restart.

When the unloader valve malfunctions, it’s often stuck open or failing to close. When it stays open, you’ll hear an almost continuous stream of leaking air. When it remains closed, the pressure buildup can lock the pump’s internal components, preventing the shaft in the engine from turning.

If your system suffers from a faulty unloader valve, it’s vital to replace it immediately because it can affect other critical components in your compressor.

What You Need to Get Started

Various air compressors have different types of unloader valves. Some valves use a toggle switch on the side of the pressure controller, while others mount directly to the unit. In either case, the materials you need to make the replacement are the same:

A Phillips or flathead screwdriver

An adjustable wrench

Adjustable pliers

Snipping pliers

Thread lubricant

The new unloader valve

Safety glasses

The Replacement Process

Before you begin, it’s critical to depressurize the tank by opening the drain valve.  When you’re ready to start, you’ll find the unloader valve connected to a hose that carries water to the recirculation pump.

Removing the Old Unloader Valve

Remove the old valve with these steps:

Unplug the compressor.

Remove the line going into the valve.

Use the adjustable pliers or wrench to remove the quick-connect fitting if it has one.

Disconnect the wires from the pressure switch.

Detach the valve.

Installing the New Unloader Valve

Perform the following to install the new valve:

Apply thread lubricant to the new valve.

Cut a small amount of the line with the snipping pliers to ensure a clean connection.

Connect the line.

Reattach the quick-connect fitting.

Attach the new valve.

Adjust the tension on the new unloader valve according to the pump manufacturer’s specified pressure.

FROM:Quincy Compressor