Could be a bad connection, or the blower motor needs replacing.
Bad motor or bad connection
ALSO SOMETIMES YOU CAN SPRAY WD-40 INTO ALL CONNECTIONS/SWITCHES AND GET LUCKY..
Looking for a Used LeSabre in your area?
CarGurus has 1,213 nationwide LeSabre listings starting at $799.
Search Buick LeSabre Questions
Buick LeSabre Experts