heat comes out passenger side and cold air out driver side, no heat with defrost

User27287 is right, flushing the coolant system will not help as you do not have an issue with your coolant system as evidenced by heat production on one side of the car. The electronic mode actuators move doors inside the HVAC ducts to channel hot or cold air to the desired location. One or more of these are not functioning properly. This is best addressed by a professional with proper scanning equipment. Here is a link to trusted mechanics in your area that will be able to help you. http://repairpal.com/ford-within-10-miles-of-oceanside-california-92057

You have a problem in the air box with the electric mode actuators, you will need a scanner that can interface with the hvac module so you can see whats working and whats not working,or you will have to access the mode actuators and visually look at them when you change the modes on the control head,Note these are very hard to gain access to sometime you need to remove the dash panel depending which actuator.