Not sure is this is the right place for the query, but here goes anyway. Now that we have started a big heat wave which should continue over the next days, I noticed that only one auxiliary fan up front is in operation with the A/C engaged (necessary these summer days). The A/C was topped up a couple of weeks ago and the system blows nice cold air inside. When does the second fan kick in? Is it for the A/C or as an extra fan should the engine get very hot (not my problem) even with the viscous fan engaged?