The air conditioner/heat pump does not convert the heat to another form, such as electricity or mechanical work, it just moves it from the air, through a medium, such as freon back to the air again. Since no conversion is taking place the power the air conditioner actually uses then accounts for the effort to move the heat and some losses of the components; the compressor and the fans.
Very good summary! I should add that the compressor work includes not only friction losses and the like, but also the work required to 'lift' the transported heat in temperature.
Any temperature difference can in theory be used to run a motor, i.e. convert the energy to another form. To calculate this efficiency is very simple:
Maximum efficiency = 1-T_low/T_high
T_low is the lowest temperature in the cycle
T_high is the highest temperature in the cycle
The temperatures must be in Kelvin or Rankine.
As you can see, the higher the ratio T_low/T_high is, the higher the efficency.
In a heat pump, you effectively invert the formula: The higher the ratio, the less efficient the heat pump becomes. Thus, a freezer is less efficient than a fridge.
[This message has been edited by C-H (edited 09-10-2003).]