Arrived and discussed issue with tenant. Found indoor and outdoor unit frozen solid with ice. I thawed unit and diagnosed initial issues are a very dirty 14x28x1 filter and low r22 refrigerant. System in 36 years old and shows it’s age and wear. Gas furnace is a standing pilot that has the gas shut off valve turned off. I highly recommend full system replacement due to age and status of equipment. If equipment is not replaced I would not run the heat until there was a complete heating maintenance or inspection done. Old 60% efficiency furnaces will have burner and flame issue when the age. Diagnosed system froze solid with ice due to a dirty custom sized air filter and low r22 refrigerant charge. We use 407c retrofit refrigerant due to r22 is no longer produced.system is 3 pounds low on refrigerant and the condensation drain line is clogged up and must be cleared out. If system takes less then 3 pounds of refrigerant price will be adjusted to match amount installed. System took jus