I am interested on understanding the unsteady period of functioning of an air conditioner system, with a traditional refrigerant, let's say R-11. Imagine there is a room which initially is at the same temperature than the external one, i.e. [tex] T_i(0)=T_e[/tex]. Just when I switch on the system, the evaporator, condenser and refrigerant are at the same temperature [tex]T_e[/tex]. I really don't see "the movie", I mean, how the refrigerant (which I think will be in liquid state) can be compressed and change its state, and how the evaporator can cause an evaporation if it is initially at the same temperature than ambient (there won't be any heat flux to absorb because both things are at the same temperature), and how the condenser can condense if it is at the same temperature than external atmosphere. The steady regimen is very easy, but I don't know how the machine starts.