Based on our findings today, it might be time to think about getting a brand new system. Today we came out for second level not cooling Lennox 2011 3.5 ton heat pump split. Cycled equipment from thermostat checked complete system found heat pump in low pressure lock out. Checked refrigerant levels found no refrigerant in circuit. Performed electronic leak search found leaks in evaporator coil manufacture warranty has expired. With equipment being almost 14 years old need to update equipment. Scheduled install supervisor to give options.