It just switches to cooling mode and activates the AUX heat to dump heat into the outdoor coils for a minute or two and then goes back to heating. The AUX heat

It just switches to cooling mode and activates the AUX heat to dump heat into the outdoor coils for a minute or two and then goes back to heating. The AUX heat is just a thermostat relay closing, so it can activate an electric-resistive coil (as is typical) or it can turn on the circulator pump for a gas fired boiler for a hydronic loop in the air handler.