My g/f has a 05 Hyundai sonata. When running the heater it's warm air coming out of all vents except the passenger side by the window. It blows out cold air.what could cause this? I thought they all came from the same heater.

Jason

 

yes, the heat source, heater core, is the same. I suspect either the cable or vacuum tube that directs and actuates the louver directionis at fault. The fix may as simple as moving the lever back and forth a few times to free the louver. otheriwse you need to check the ductwork and/or thatthe louver is binding preventingthe directed heated air from reaching the vent.