Filter is a 20 x 20 x1. Change filter. Clean drain. Check all electronic components. checked all three zone dampers. All three test fine. Checked amps on heat strip and blower motor. Both test fine. found heat pump with no refrigeration. Found crack in elbow to low pressure switch. Repaired crack In line. I added 10 pounds for 410a. Everything covered under warranty. Vacuum down to 500 µm. Heat pump performing as it should.