search "starcool" on this forum. read everything but the member classified posts.
You should run the fan when driving with the automotive A/C on.
That means the fan speed control set to one of it's three speeds and the rocker switch behind the drivers seat set to on and the thermostat set to off.
If you're parked with the engine off and not on shore power or generator I would not run the fan.
All that being said, tell us about your SMB. Post pics, make a garage album.
Give us something to work with
The institutional memory on this forum is awesome.
'07 GMC 2500 6.0