Heater/Defroster on 2001 Mitsubishi Eclipse

When I run my heater or defroster there is nothing but cold air that comes out on the drivers side. The passenger side has warm air coming out of the vents but not the driver side. Any ideas what is the problem.

Asked by for the 2001 Mitsubishi Eclipse
There may be a restriction in the air ducts (we see a lot of mice nesting this time of year particularly if the car has been parked for a longer period of time). It may be as simple as an air duct that has become dislodged particularly if someone has done any electrical work/ replaced the stereo ect.... behind the dash. It may also be due to a control (either electrical/vacuum operated flap, or a control cable) that has failed.
Autozone have some popular workshop manuals for free on line once you register (for free) on their website .There is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You get a one year subscription to year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual. or try and get an online repair manual subscription.
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The cable that operates hot to cold is visable from the drivers side floorboard. The cable housing comes out off the retainer clip so it doesn't move the lever to hot very well. Either put cable back into its holder or move lever manually and repair as needed later.