Came out today for a Lennox heat pump not cooling. Model #cbx25uh02423010, serial #1716L20042. Upon inspection I found that the condenser was locked out on high pressure. The condenser coil’s are clean and in good condition but the air filter was severely clogged. The air filter was dated 6/16/21. I advised the homeowner that the filter should be replaced every 2-3 months. I replaced the air filter and reset the pressure switch. The system started right up. The temperature split is at a 19. The refrigerant pressures are 149/275. These are normal readings for the temperature outside today. The system is operating properly at this time