Driver's Side Warm, Passenger Side Nice and Cold .... 2002 Olds Silhoette Minivan A/C

Our van has the two range temperature control and lately the driver's side will only get luke-warm while the passenger side's vents are
blowing nice and cold.
Has anyone seen this before and can you suggest how to fix it?
Unfortunately the Major Guard warranty ran out just 1,500 miles ago. Does GM ever give a little leeway on Major Guard coverage?
TIA for any help, John
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