That's hard to say without knowing what the original problem was or if there were multiple problems. It's very rare for more than one part to fail at the same time. That being said, it's possible if the inverter failed, the manufacturer says the mag tube should be replaced at the same time even if it tests good. Unfortunately I don't have any service information on that particular model but I'm still looking. The appliance manager is on the low voltage side and supplies the voltage (120 VAC) to the inverter and the inverter supplies the high voltage to the mag tube. When testing for a no heat problem you need to take a lot of DC volt measurements. If he checked the appliance manager and found it was bad, not supplying the voltage to the inverter, then how would he know the inverter and mag tube is bad. If the appliance manager was supplying the correct voltage to the inverter then why is it being replaced? The mag tube is the easiest to test without power.
If you go by the process of elimination you can end up replacing all three parts anyways. Did he leave you any part numbers for the parts? Do you have a
DMM and can you take voltage measurements? I'll need to locate the tech sheet first before I can tell you where to test. My guess, and it's just a guess, the machine was running and counting down just not heating. He was inexperienced and couldn't determine what part failed so if he replaced all three, he covered his a$$ at your expense. Like I said, just a guess.
