How it works When the ac switches on with the thermostat, the compressor and outdoor fan motor begin to operate. then later the furnace’s blower draws hot air through the return vents and duct, then the blower passes it over the refrigerated coils. The blower’s force then sends that cold air to the rooms via the supply ducts. Heating: the outdoor unit is left off in heating First the control board of the furnace does a check to say that everything is okay to start the inducer, the inducer draws the air around the furnace into the furnace for combustion, then the board does another check then the ignitor begins to glow. then the valve opens allowing gas to flow over the ignitor and the gas be lit. then later after the whole ignition sequence is successful. The blower comes on. The inducer sucks the toxic gases out of the furnace and through a flue pipe. Satisfaction is a period when the air conditioner/heating shuts off because the thermostat no longer needs heating or cooling. Defrost is when a heat pump stops to send warm refrigerant to melt the frost on the condenser when it accumulates frost. during this period the heating will stop and often some thermostats will tell you that the system’s in defrost mode.
