AC not working on drivers side, only hot temp, dual controls set at 60 degrees. on 2005 GMC Sierra 2500 HD

Both driver and passenger dual controls are set at 60 degrees with AC on. Driver side will only blow hot heated air. Passenger side will blow cold. Fuses look OK. Any ideas on what the problem could be.

Asked by for the 2005 GMC Sierra 2500 HD
Your problem may be in the controller itself or the blend door which switches from cold to hot air.