the driver side blows cold air when it is set to warm on 2008 Mercury Mariner

why does the driver side blow cold air ,when the temp setting is on warm?

Asked by for the 2008 Mercury Mariner
Chances are there is a problem with the driver side temperature control actuator. Your 2008 Mercury Mariner may still be under warranty for this. Perhaps a trip to your local dealer would be in order.
3 more answers
Seems that this is going to be a common problem for this model. Mine is doing the same thing.
I went to the dealership for this. I had this problems and audible clicking coming from the dash. They told me the air vent motor was going out and would have to be replaced. First response I got was this was not covered under warranty and would be $400 to replace.
Mine did the same thing on an intermittent basis. The problem was the blend-doors (Dual Zone Climate Control) which were replaced and now works perfectly.