I have been having problems with my 1995 Isuzu Trooper. My fan comes on sometimes and shuts off at will. On and off. I changed the fan blower and the resistor, but I still get the same problem intermittently. This happens when I am driving or stopped. When the fan shuts off, my battery trouble light comes on, when the fan starts again, the battery trouble light goes off. Any ideas what my problem is? Thanks.