Hello, my heat only blows warm from the passenger side. The driver side blows very luke warm to cool unless it is 50 degrees or better outside. I have had my blend door and thermostat change and it's still happening. Mechanic said I had a blockage from stop leak that they cleared. Has anyone had a problem like this. Would it be the heater core. It's hot air blowing from the passenger side that get gradually cooler as it moves to the driver side. And again it works based on the outside temperature. Thanks for any help or suggestions