The more I learn about the fan controls and their apparent inconsistent (read; unreliable) performance, the more I am inclined to follow Oztules lead and put in place independent fan control. I remember reading that Oz built his own, but I'll probably buy a temp control card off ebay (dirt cheap) and just parallel its switch with the existing inverter's sensor. That way, whichever control wants the fan on first wins, and my inverter stays cool either way. Maybe even two cards; one for heatsink temp and one for coil temp. Two temp control cards with sensors for less than $10US total is too cheap NOT to use.
I have noted in the past that some days the inverter seems to run hotter than other days, but without actual temp readings, I just thought it was my imagination. Not so sure now... The cards I'm looking at will also give a constant temp reading, which is a nice plus.
I guess that just leaves us with the question of where to put the setpoints. On at 40-45 maybe and off at maybe 35? Oztules, what setpoints did you use and did you sense at the heatsink or on a coil, or both?
dochubert