On 4/21/2011 3:42 PM, Jan Philips wrote:
It is me with problem with the upstairs heat pump again. When the
compressor comes on, the fan on the compressor starts. Usually within
a few seconds, the fan motor shuts off but the compressor keeps
running. Before the fan can completely spin down, the fan motor comes
on again. It often keeps repeating this, so it is only blowing out
the hot air about half the time the compressor is running. I think
this must hurt efficiency. What could be the problem?

Most heat pumps are setup to cycle the condenser fan motor which will
cut on and off during moderate to cold outdoor temperatures. I include a
condenser fan cycling control on all standard AC units I install for
restaurants because the AC is usually run year round and the pressure
in the liquid line from the condenser needs to be kept high enough for
the AC to operate properly. Some conventional straight AC condensing
units have a two speed condenser fan motor and the control may actually
cycle the fan on and off if it's cold enough outdoors. You can spend
even more money and get a heat pump that has variable speed compressor
and fan motors. :-)

TDD