For this job I performed a heating tune-up. I discovered that the unit had low refrigerant and that the dual fuel system was running improperly. Both heat pump and furnace were running at the same time. I explained to homeowner when that happens it overheats the refrigerant and makes it acidic and will lead to compressor failure. Outdoor thermostat recommended to mitigate the issue of running both furnace and heat pump at the same time. I gave homeowner a starting point and diagnostics trying to pinpoint where the leaks are coming from and replace the filter dryer due to acidic refrigerant running in the unit. I offered homeowner a comfort advisor to go and give an estimate for a system replacement due to age and condition of the unit. Homeowner opted to hold off on Comfort advisor for the meanwhile they did request email with the estimates and stated that they would call back in a week or so to have the outdoor thermostat added. Homeowner was made aware that we are not sure if we will