Subaru Outback windows fogged up then stopped

My 2001 Subaru Outback wagon windows where fogging up for about a week.....That
stopped then a few weeks later car is running hot...Had head gaskets, water pump, belt,
therosate all replaced last year....My mechanic can't find anything that looks like a head
gasket problem again....No loss of compression, no white smoke, no anti freeze mixing
with oil, no leaks of any fluid....Decided to chance replacing water pump and belt and
therosate and cap again and it's still running hot....Everything checked out even radiator
is looking good....What else could make it run hot???????? My mechanic is puzzled