Never seem to come on. I spent about an hour in the driveway (with no fan running) trying to get the truck to run hotter than it normally runs. The outside temp was only about 72 degrees, but still, I was reving it in the driveway and I even put it in gear and stalled it up a time or two.
I finally got it to run a little hotter than normal and I set the Flex-a-lite fans to come on there. I wonder if my factory temp guage is not very accurate? Maybe it has stopped in the same place for so many years (truck is a 2000) it's gets kinda stuck there and doesn't want to go any higher even though the real temp is higher?
If the temp guage is correct I don't think the fans will be coming on very much, unless the A/C is on. It seems like not having a fan running (even though it had a clutch fan) would have to be good for a little power and help the gas mileage a little.
When the PCM is used to control the fans do they come on very often?