Despite how the Cruise Air installations may look I think both Marathon and Liberty set ups are fairly easy to service.

The Marathon has access via swing out(s), and the Liberty installation has sufficient room to access the valves. The run and start capacitors are also easily accessed.

If the fan has to be replaced or the coils need cleaning that may involve the disconnection and removal of the condensing units, but other than that given the amount of space available they can be serviced. If the compressor has failed, just remove and replace the whole thing, also fairly easy.