2004 Envoy Heater partially working

My 2004 Envoy's heater is partially working. The driver's side heater works and blows hot air. The passenger side is not blowing hot air. It only blows cold air. The rear overhead blowers blow hot air, but the feet blowers blow cold. I was told that I needed to get a new actuator installed. It is alot of money. I want to have feedback from others if you have had this problem. Any information you have would be appreciated. Thanks!