Preformed furnace/maintenance On two system Lennox. Upon my maintenance XC20 fan motor Was intermittently working and not running at the proper capacity. Determine that fan motor is going bad and will order new one under warranty although labor warranty is expired. Also found that system is not equipped with surge protection on both indoor and outdoor units. Discussed That surge protector should at least be put on outdoor unit to protect ECM motors and compressor to increase longevity of AC systems. Performed maintenance on AC systems and cleaned off condenser coil’s and checked refrigerant pressures. All components on AC system besides fan motor checked out. Performed maintenance on furnaces and double checked temperature rise along with secured all gas fittings and ensured no gas leaks. Filters are both replace due to cat hair buildup. Recommended that indoor air quality upgrade with whole house purifier that can be installed to increase the life of the system and reduce dust build