Auxillery fan

[bison]

I just found out i got an auxillery fan in the cab(popped a fuse in a emty slot in the fuse box and a fan started wirring)
It runs as soon as i turn the key on.

Any idea why it's there and what for?

 

[JiFaire]

Where is it? In the air system, or on some electronics?

 

[great white]

Which truck?

Where is this fan located?

With fuse position did you put the "new" fuse in?

 

[WarWagon]

Climate control fan for a temp sensor often mistaken for OnStar microphone, radio cooling fan, blower on low even with HVAC off are all the possible fans I know about.

 

[bison]

It's in the 98.
It sounds like the fan is in te same corner as the AC/Heater fan or it might be just another speed on this fan(i didn't investigate).

It says Aux fan on the under hood fuse box cover(there was never a use in it as long as i have the truck)
All underhood AC components have been removed incl rad core

 

[88gmctruck]

hum.......... I'm tempted to see if my 99 has this mystery fan.......

 

[88gmctruck]

Well, my aux fan fuse only has one contact, which is they keyed hot. I actually used it for the air compressor.

 

[Burning oil]

I bet its for the aux electric radiator fan on the 454 gasser??

 

[88gmctruck]

Looked up the wiring in my FSM for my 99 (should be the same as a 98) and the aux fan fuse powers the far relay which powers the aux fan on the front of the truck. No idea what yours is doing.

 

[bison]

Looked up the wiring in my FSM for my 99 (should be the same as a 98) and the aux fan fuse powers the far relay which powers the aux fan on the front of the truck. No idea what yours is doing.

It's making fan noise in the cab that's all i know:???:
I'll see about the relay,it might not even be there.