Occasional "Click"

[pedalquickly]

Every so often I hear a fairly loud "click" coming from the engine compartment. I have never heard it from outside the vehicle, but only while Im driving. It sounds like someone tapping and empty soda can once. I can't tell when it might do it. It does it when the A/C is off, otherwise I would suspect the compressor clutch.

I think it is a large relay or something? A relay in the charging system?

Anyone else have this?

 

[92Pony]

Just a shot.......

You probably already know this, but the A/C compressor runs when using the defrost also - is it happening when you're running the defrost?

 

[terrond]

I've notice this also in the past few months - a kind of air sucking sound followed by a click - even when the a/c or defrost is off.

 

[pedalquickly]

It does it with defrost and ac off. Really sounds like a big relay. Is there any type of relay associated with the air flow sensor or charging circuit?