Also known as an externally-piloted pneumatic solenoid valve, the mechanism works similarly to other solenoid valves but uses air pressure to help keep the valve closed. These are often used where the system has low pressure, vacuum or if there is low, negative or absent pressure in the valve itself.

If the air solenoid valve is not opening or closing, leaking, or overheating, these are signs that it is damaged or that there is a wiring issue. Any Solenoid valve can be tested with a multimeter by following these steps:

1. Set the multimeter to ‘ohms’ (Ω) to test for continuity.
2. Touch the multimeter’s red lead to the positive (+) terminal of the solenoid valve, and the black lead to the negative (-) terminal. These will be metal pins or spade connectors used for wiring. If there are 3, the smallest will be used to ground the circuit.
3. Connect the solenoid to a power source and apply the current. Once the current is flowing through the circuit, you should hear a click of the solenoid valve moving. If you don’t hear this, the solenoid coil isn’t working properly and needs replacing.
4. If you did hear the click, then check the continuity reading on the multimeter display. You should have a low ohm reading between 0 and
   1. 1. Any other reading indicates that the solenoid needs replacing.