After installing a new battery, I find the alternator is not good. It shows a charging voltage of only 11.8V . Could this be the cause of the engine heating.The aux fan could be running slow due to the low output from the batteries. I am only trying to think, dont know.I asked the mechanic to get a new alternator. Hope this helps. My old AC Delco maintenance battery lasted only 10 months. If I get a refurbished alternator what should I check. Any advise is appreciated.