System heat pump running but not functioning due to low refrigerant charge. Equipment was recharged with leak stop and die and 4 lb of Purpn 8-25-23 Today's visit showed instant freezing at the outdoor piston and heat mode and very low suction pressures 82 PSI. book specs for 65 outdoor and 70 indoor are closer to 130 suction pressure Cooling mode run test for recharge also indicated very low refrigerant pressures with 1.2 subcooling and 54 superheat Recharge heat pump system with 8 lb new R410A to achieve book specs of 9.5 subcooling with running cooling refrigerant pressures of 105 and 236. Cooling mode superheat 18. System has required extensive refrigerant recharges multiple times and is also beyond the normal life expectancy of a outdoor air-to-air heat pump system. The leak stop injected in 2023 did not resolve the issues and no ultraviolet dye was visible today. *Recommend budgeting for new cooling system in the very near future