Could be the climate control unit itself. Mine had the same symptoms. Some times it would take a while and other times I would have the exact same experience as you're having. Got one from the junkyard for $12.
This is a link to my thread
http://www.automotiveforums.com/vbul...d.php?t=954958.
Don't no if you have the digital readout or the manuel one. But I would assume both are prone to failure.
You would pass out if you knew the price on a new unit. $500+
