LIMIT SWITCH The Lennox® Limit Switch is an electromechanical device interposed between a power control and a safety-related circuit It monitors the position of the limit switch actuator (a solenoid valve motor in this case) and opens or closes a circuit as required to protect the motor and/ or the equipment from damage Lennox 53J09 Limit Switch The Limit Switch is a heat source operated control designed to limit the heat operation of the furnace The 53J09 Limit Switch fits Lennox air conditioners, furnaces, humidifiers, and boilers made within the last 5 years The Lennox 53J09 Limit Switch is used to control the burner jets in a furnace via the modulating control system Electronic limit switches control the velocity and stop function of moving belts or chain drive systems Our Lennox Limit Exhaust Fan limit switch is able to fit two condensing unit types This 53J09 Limit Exhaust Fan limit switch can be installed with our AP3036K09 and CCP3036K09 Outdoor Condensing Units Controlling your fan with a limit switch ensures that you are using less energy, which saves money on your heating bill!