I have a 1993 Plymouth Voyager with 192,000 miles, 6cyl, 3L engine. My radiator fan is not coming on unless the air conditioner is running. I frequently drive with the A/C off to TRY to save gas. If I stop moving while in traffic due to road construction, etc, after about 15 minutes, my temp gauge starts migrating to the hot section. Once I starting moving again my temperature gauge moves back to straight up (normal). My fan DOES NOT kick off and on. If I turn my A/C ON, my fan starts up. Can you help me?