Frequency solenoid C

[SunSun]

I wanted to check if my frequency solenoid C was working, so I listened to it and felt of it. It was vibrating. However, it had a rubber cap on the top where the air filter should have been, so it wasn't getting any air. I replaced the cap with the filter that I borrowed from the AC solenoid, since it doesn't operate in the winter. Is it possible that the cap was OEM and the solenoid should not be functioning on my car?

[poncho-lx]

the rubber cap is not removed.
the solenoid valve should be clicking on and off continuously.
your thread is in the wrong place

[SunSun]

Thanks for the info. I capped it again.