On the Ford Edge, which blows cold on the driver's side; I believe this is caused by a problem with the heater left blend door actuator. A vehicle's HVAC system (heating, ventilation, and air conditioning) is a
key component to driving comfort and proper vehicle operation. The HVAC
air door actuator regulates this flow of cold and hot air in the
vehicle's cabin. If the motor burns out or the shaft cracks, the door
can get stuck in one position leading to improper ventilation That part is available from rock auto online. Replace the left blend door actuator and it will fix this.
There are several different blend door configurations; so it is necessary to know which side is bad, and what typr of HVAC system the vehicle has. The other post, which was not about a Ford Edge, may require a different type of blend door.