I bought another 55 last week. When I hit 70 mph it has a sound like a bad THROUGH OUT Bearing. The sound CYCLES on Off. I can feel and RPM change as it cycles. Now I can turn the A/C off and this sound still cycles. In town the A/C is VERY COLD. Even at its lowest. I drove 100+ miles Sat. AM and other than the sound it worked fine. Sat After noon in much more heat on the return the COLD AIR went away. But on the exit ramp at home it came back cold. The sound may not be related to the A/C. When I have time I will Remove the belt to see if the sound is the A/C. Oh and when I stand on it I have a belt sequel. Any ideas why the air went away?