Why might the passenger side air conditioning in a 2002 Mercury Mountaineer not cool on normal dual or single AC mode?

Hey Paul==Evidentally one of the doors aren't working correctly. It probably needs to be checked out by someone familiar with the a/c. GoodluckJoe The Mercury dealership found the problem to be a defective evaporator. Only 1 month out of warranty at 37,000 miles the evaporator was replaced at a cost of $1,000. Most of the cost was labor removing and reinstalling the dash. I hope this one lasts longer than the factory installed unit. The replacement has a 12 month/12,000 mile warranty.