How do I know if a part that a HVAC service technician is telling me isn’t working really isn’t working?

Hopefully you will always be able to trust the HVAC company you have called out. We suggest that if you suspect there is something not right, you should ask the technician to show you the test he used to condemn the part. If you still have reason to suspect, call the service manager of the company and ask him to explain how one would determine how to check a component for failure. If their stories don’t match than kick them in the rear as you ask them to leave…..