Replacing board and 2 sequencers.air handler working properly. New board and heat strips installed. During testing noticed outdoor unit not running. Outdoor heat pump off on low pressure due to completely empty of refrigerant. Fins of outdoor coil corroded and leaking. System will not hold a charge due to the size of the leak. System is r-22 refrigerant and will be unavailable Jan 2020 due to EPA regulations. If heat pump is replaced the evaporator coil upstairs will also have to be replaced do to the pressure difference and the inability to flush r-22 out of the coil. All new systems use 410a refrigerant. The two options to fix the situation are to replace the heat pump and the upstairs coil or replace the entire system which is the recommended action because of the warranty and efficiency difference. Heat is operating solely on emergency heat and the outdoor unit will remain inoperable until it is replaced.