A Low Ambient Kit is intended to maintain system pressures at normal levels should indoor cooling be required when outdoor temperatures are low. The kit works by slowing the condenser fan to maintain head pressure by varying the air flow through the outside evaporator coil. This is accomplished by measuring the liquid temperature at the coil and based on the temperature the ambient kit will automatically adjust the motor speed to prevent freezing. 

These kits are not approved for any 16 and 18 SEER outdoor units that utilize an ECM condensor fan motor.