I got a strange problem with my BJ70 heater fan. The heater fan work great at HI but after severale minute it stop. This problem seem to occure when I select hot temperature (Don't seem to happen for cold temperature (??)). The strange thing is the fan work again after it stop for a medium-long period. Is that problem come from a bad "resistance" in the fan motor ? Where is that "resistance"? How hard is to change it ? Is that already happen to someone ?