  The direction of the steady-state heat currents across a generic quantum
system connected to multiple baths may be engineered so as to realize virtually
any thermodynamic cycle. In spite of their versatility such continuous
energy-conversion systems are generally unable to operate at maximum efficiency
due to non-negligible sources of irreversible entropy production. In this paper
we introduce a minimal model of irreversible absorption chiller. We identify
and characterize the different mechanisms responsible for its irreversibility,
namely heat leaks and internal dissipation, and gauge their relative impact in
the overall cooling performance. We also propose reservoir engineering
techniques to minimize these detrimental effects. Finally, by looking into a
known three-qubit embodiment of the absorption cooling cycle, we illustrate how
our simple model may help to pinpoint the different sources of irreversibility
naturally arising in more complex practical heat devices.
