A compressed air supply unit for operating a pneumatic unit by means of a compressed air flow, in particular of an air suspension unit of a vehicle, comprises an air dryer arrangement in a main pneumatic line that pneumatically links a compressed air feed line from an air compressor and a compressed air connection to the pneumatic unit. A valve arrangement is pneumatically connected to the main pneumatic line for controlling the compressed air flow. The air dryer arrangement has a drying container having a container outer wall. A partition along a length of the drying container divides an internal space delimited by the container outer wall into first and second chambers delimited by the partition and the container outer wall. The partition adjoins the container outer wall along the length of the drying container, and the first and second chambers are adjacent to one another along that length.