Aux fan stupid question

[tk0084]

Ok, I am now confused on the purpose of the Aux fan. My fan does not currently work, could be the temp sensor, a missing fuse or a bad fan (haven't started to diagnosis yet) but as I've done some reading it prompted a question.

Is the Aux fan only suppose to run when the AC is on?

If yes, then my reason(s) that the aux fan is answered since my AC doesn't work pully seazed & no belt hooked up to it, not to mention vacuum issues & who knows what else.

Thanks for any answers.

[aam]

Originally Posted by tk0084

Ok, I am now confused on the purpose of the Aux fan. My fan does not currently work, could be the temp sensor, a missing fuse or a bad fan (haven't started to diagnosis yet) but as I've done some reading it prompted a question.

Is the Aux fan only suppose to run when the AC is on?

If yes, then my reason(s) that the aux fan is answered since my AC doesn't work pully seazed & no belt hooked up to it, not to mention vacuum issues & who knows what else.

Thanks for any answers.

More info.
what year is your car?
Aux, Fans are working when the a/c is on.
Or overheating.
Regards,
aam.

[tk0084]

1980 450SL.

Aux fan does not work, AC does not work either. No belts hooked up for AC.

Car doesn't overheat but when sitting in traffic it gets very hot, never gotten into the red but it gets up there.

I did a search for Aux fan which resulted my original post.

Thanks & sorry I forgot to list car info.

[280EZRider]

The aux fan comes on when 1) over pressure in a/c system sensed at receiver/dryer and/or 2) overheating of coolant sensed at sensor box on a head - not water-temp sending unit. Powered thru fuse panel and ice cube relay.