To begin, we will look at the difference between the two types of motors.
What's the difference between a PSC and an ECM motor?
A permanent split capacitor (PSC) motor uses a capacitor that is installed between the run and start windings of a motor. This capacitor helps the motor to start and to maintain the speed of the motor. In an ECM motor the speed of the motor is controlled by an electronic circuit board. An ECM motor uses about 75% less electrical power to perform the same amount of work than a comparable PSC motor. The ECM motor typically lasts two times longer than a PSC motor because it has less friction during operation and therefore produces less heat inside the motor.
What about the cost and time to payback?
The average PSC motor for the fan on a central air conditioner will cost about $100 (more for the direct replacement from a manufacturer) while the cost of an equivalent ECM replacement motor will be around $150. The payback time will depend on where you live and how much you run your air conditioner. It would take several years for those who live in northern climates and don't run their ac that much while it could be two years or less for those in the warmer climates.
What is the air conditioner fan upgrade process?
The first step is to assess your air conditioner and the existing fan motor. If it has a standard 5.5 inch diameter motor, then the process is very simple. You can purchase the upgraded motor from Amazon. The differences in the replacement procedure are as follows: For the ECM upgrade motor, the motor must be programmed prior to putting on the fan blade or installing it in the unit. The motor comes with a programming cable that is attached to the motor connector and then plugged into a standard 115 volt outlet. The motor will cycle through its four modes of operation in about 90 seconds. When you see the motor rotating in the proper direction and at the proper speed, you unplug the programming cable from the outlet and the motor will then be programmed to operate in that mode. (Don't worry if you do not get it right the first time as the process can be repeated as many times as you need.) After the motor is mounted, you need to remove the rubber drain plugs from the end of the motor that is in the lower position. Route the wires to the control box and then plug them into the external surge protector. Connect the L1 and L2 leads from the surge protector to the unit's contactor and the ground wire to a suitable equipment ground connection.