Does anyone have experience troubleshooting erratic heater/AC blower fan operation on a 2003 SE? It works when it wants, sometimes several minutes after being selected, sometimes not at all. It is a problem with all functions (AC, heat and defrost). I suspected a loose connection, but haven't found one. I was told it could be a ground issue or the HVAC control module but don't know where it is located or how to check it. Any help would be appreciated.