Intercooler fan operation

Hi I have searched for an answer but can not find one.

I have a rd28t and have never noticed the intercooler fan operating.
Today while doing some basic cleaning with the engine running, I removed the plastic clip (sensor) from the front of the intercooler and the fan started up. The interesting thing is when i placed the clip back on the fan stopped.

The main question that i put to you is, what would the pro's and con's be of running this either full time or on a switch like my second thermo fan?

I run mine fulltime. My fan is underneath and sucks air in. You only really need it for slow speed work. I would forget to turn it on