When making repairs on A/C equipment here is why you should use OEM (Original Equipment Manufacturing) parts. Evaporator motors now days are using X13 and ECM (Electronically Commutated Motors). These motors are engineered and are factory preset for specific air volume. The manufactures have designed them for use in their equipment (gas furnaces and air handlers). This is why you need to replace that motor with the part that the manufacturer has designed for that equipment. Two stage gas furnaces use a variable speed draft blower motor which operates low and high, which draw combustion gases through the heat exchanger to maximize heating efficiency. 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.