97 Park Ave, no heat, drivers side only

I have read on this forum about the passenger side not blowing heat but my problem is the opposite- the drivers side blows cold air while the passenger side is fine. This goes for the heater & defroster. I tried turning the temp up to 90 but it still blows cold air on drivers side. It doesnt seem to be the thermometer....any other helpful ideas I can try before having to take 'er in?

Sounds simular to the pass. problems. Either way I'd go with what the recommendations are on those posts first.