All equipment manufactures engineer these motors differently. Printed circuit boards in furnaces and air handlers use self diagnostic controls managing every function with digital accuracy. These controls include safety features and operation perimeters that differ from one piece of equipment to the other. When determining proper freon charge, the service information shipped with the new residential and commercial systems contains tables that allow you to establish what the system operating condition should be under normal circumstances. Proper use of this information is vital to reliable system operation and maximum system efficiency and capacity. This is why you should use OEM parts. Hope this helps.