I have a 2012 Silverado LTZ and blowing cold air out of Pass. side and hot out of the drivers. Any thoughts?

 

Sounds like the blend door is bad/ stuck, I would look into replacing them because that’s what controls what air goes where’s and the temperature as well. There is 3 different ones, one for her driver side vents, passenger side vents and usually in the counter that controls the temperature. Sounds like you have cold and hot air but the vents are blowing out two different temps at the same time so I would def change the blend door actuators

 

ditto. bad temp blend door actuator or stuck/broken blend door. if the doors and door motors are good...partially blocked heater core is another possiblity