I have a 2006 Winnebago with the Coleman basement ac. All functions properly, voltage, etc. (heat and cooling are not up to snuff). The compressors start correctly but when they do there is a very loud almost harmonic vibration that fades in and out. I have replaced the fan motors and bearings hoping it was the problem, no such luck. I am ready to buy a new unit from Dyers, I would just like to know if a new unit is quiter.