- When the solenoid is de-energized, the air flow stops at port 1.
- When the solenoid is energized, the air flows through port 1 and out through port 2.
- If the power fails, air flow stops. The solenoid goes back to its de-energized position.
The air-purge solenoid is energized on a timed cycle. If too much contamination collects inside the solenoid, leaks from the outlet port can occur. You can manually energize some brands of solenoids. This has no effect on the time cycle.
ASCO or SMC brand 2-Port solenoid valves are most commonly used for the air system purge. These solenoids are also used in the Coolant Refill and TAB options.
Note: MAC 3-Port poppet style solenoid valves are also used for the air system purge. There is a plug on port number 3 when MAC 3-way poppet style solenoid valves are used. If there is a leak from one of the ports on a MAC 3-Port poppet style solenoid valve, push the manual activation button multiple times to clear out any debris in the solenoid. If this does not work, remove the solenoid and clean it with compressed air while cycling the solenoid. If a MAC purge solenoid replacement is necessary, do not substitute a different MAC solenoid. Use the approved replacement solenoid.
If these solenoids leak air when the solenoid is not activated, it is likely that debris holds the plunger in an open position. Follow this procedures to clean the 2-Port air purge solenoid valve: