I heard back from Coleman. The AC is 2-1/2 years old. Coleman said that if it had failed within 2 years, they would have covered the replacement. Since it is 6 months past warrenty then the failure was caused by vibration and not covered. Our AC guy said since this unit has the new type freon he is not comfortable with putting in a valve for recharging. I guess the new style freon operates under a higher pressure than the old. I'm going to call a RV place today to see what they recommend - recharging or replacing.