j-d wrote:
If you're running FAN on AUTO, something counter-intuitive happens. You're saving power, but.... When the Thermostat is satisfied (it's cool enough) Fan shuts off and Compressor cuts off. OK, good. Then Thermostat calls for cooling again. Fan AND Compressor try to start at the same time. You draw the Start Amps for both simultaneously. Some OP's here have built a delay circuit so one starts a few seconds before the other. I forget which they start first. Modern residential units run Fan a few seconds before Compressor and leave it running a few seconds after Compressor cuts out. Idea is to get the air moving before cooling starts, then take the last of the cool off of the evaporator coil after the refrigerant flow starts.
the mod I did, mostly to help starting from a small generator, is to add a 15 second time delay to the fan after the thermostat calls for cooling. this allows the compressor to get started and running and the genertor to recover, then the fan motor kicks in. Fan isn't a big load, but they also are usually a split phase motor or only have a small starting cap, so it does cut down on the total starting current draw. Every little bit helps.
the other way around is how my house unit runs, but there the objective is different. Starting isn't a problem, but you want to eak out every bit of cooling efficiency so gettting air moving over the coils first and extracting the last bit of cold air from the coils is what is needed.
