the doors seem to get stuck more readly when older. the one thing that can contribute is mold in the A/C condensor. it acts like glue when laying on the seals and things. if you can get it operate freely try spraying some Lysol or other antibactieral spray into the intake duct out under the edge of the hood. it may pull enough into the duct while running to help free the doors. under dealership conditions we would pull the entire duct work and clean. then reinstall at what ever cost it incures.