You need to state year and Model of RV and the Brand and model of the Heat Pump. Winne usually has RVP Heat Pumps depending on the year. Click this link and look at this specific outer top shroud. IF you have this model, DO NOT RUN THE HEAT PUMP AT ALL. This model has a problem with the Condensor Motor and Fan blade breaking loose and then full shut down and no operation. The noise you state is the noise these models make when they are in the process of failing. Doug
http://www.airxcel.com/coleman-mach/products/heat-pumps/mach-8-hp-15000