A/C Aux fan question.

[T.Dot E30]

I've never seen my aux fan work. Is it suspose to come on when the a/c is on? or only when the temp gets too high?

I tried testing it, I get power and 2 gounds on the 3 wires going to it. Im thinking mine might not be working.

Any ideas on how to test it or jus replace it?

[AdamF 88iS]

It should run at low speed whenever the A/C button is on.

The 2 grounds are for the different speeds the fan can run at. Low speed comes on without the A/C at a little past half on the temp gauge, and it'll kick on high speed as it gets 'round 3/4ths on the gauge.