Based on our findings today, it might be time to think about getting a brand new system. Gas company came out and shut off the valve to the system. Found flame sensor to be dirty. Zone dampers do not close when thermostat satisfies. Lots of bacterial growth in system. Heat exchanger is rusted out. Inducer is over anmoing. Gas connections are very old and corroded. Outdoor coil is very dirty. Do not recommend repairs due to cost and warranty purposes.