Return visit to evaluate Lennox gas furnace. Warranty cold end header box, inducer assembly and new pressure switches were installed by PT on Friday, 01/14/22. On arrival today I tested the furnace before replacing any more parts and everything worked. I performed several more tests with exhaust and intake piping connected and the system successfully fired every startup with no error codes. I went through the system again to clear all tubing and vacuum any PVC shavings. Inspected outdoor exhaust and intake piping and everything is clear. System is operating properly and switching from 1st and 2nd stage heat as it was designed to do.