No heat. Found system to be running upon arrival. Customer reset breaker and furnace started working. Fikter was changed just before arriving as well. Upon inspection found very corroded/rusty burner compartment with flue pipe rusty as well as improperly tied together with water heater. Found system to have cracked heat exchanger, system is low on return air , dirty blower wheel with minimal flood protection on system as well. Quoted repairs. Customer just moving into home and is staying in hotel at this time while renovations are completed. Informed customer of cracked heat exchanger advised not to use heat due to safety concerns and left thermostat in off position.