So my car is a ford focus 2008 se, mileage is 132,000 and there are no codes. When I start the car and then turn on the fan and then heater(the heater is set to %100), there is only warm air on the passenger side and neutral (whatever the temp is outside) on the driver side. I have changed the blend door actuator but that has not solved it. I've also changed positions too, such as to where the feet are and then to the face (or upper torso). They both blow neutral air but only on the driver side.
Check the coolant level. If it is low, add some coolant. If the level is fine, odds are that your heater core is clogged up and you need to drain it. There are some videos online about this. Good luck.
@yaser
thank you, I will check the heater core and see how it goes from there
@yaser
If the heater hoses are accessible, reverse flushing the heater core with a garden hose may get the crud out.