" wrote:

The most inexpensive residential AC systems lack a factory
installed head pressure control which is why it's not prudent
to run them in cold weather.

Why couldn't a thermostat that can sense condenser coil temperature
be used to turn on the fan when the coils reach some pre-determined
temperature?

Because it's not needed and just one more thing to fail
and would then need to be serviced. As for the AC being
damaged by operating it lower than 60F, personally I
think it's BS.

I don't think the AC would dammaged by low-temperature operation, but
clearly the efficiency of heat-transfer would be affected if the
operation of the condenser fan resulted in insufficient line-pressure in
the evaporator line.

This would explain why most residential AC units don't seem to cool a
house very well when ambient outdoor temperatures reach "room
temperature".