Well....last year heater was working fine , but today it only blows warm air out of 2 passenger side vents. Cold air blows out of the 2 driver side vents. I switched to defrost and same thing; driver side will blow cold air and passenger side warm air. I searched other posts but couldnt find how to fix this specific problem. I will try the funnel method to bleed cooling system....it just seems unusual that only half of the vents would work and the other half wouldnt. I also looked at the service manual , but I couldnt figure out if there was some type of lever that would seperate pasenger and driver side of vents. Any help or ideas would be appreciated.