Foam dispensers having a housing and an air compressor connected to the housing are disclosed herein. The air compressor releasably mates with a refill unit. The refill includes a container and liquid pump housing. The liquid pump housing includes: a liquid reservoir; an inlet valve; an outlet valve; an air inlet opening through the liquid pump housing; a foaming screen; and a foam dispensing nozzle secured to the liquid pump housing. The liquid pump housing is configured to releasably mate with an air compressor that is not part of the refill unit but is secured to a foam pump dispenser housing, and the refill unit is configured to be removed from the foam dispenser without removing the air compressor from the foam dispenser.