AC Fan went out on our 3 y/o Carrier system tonight. I can’t go back to the guy that installed it because he’s unreliable. Fan won’t run even when AC is off and set to the Fan On position. The black insulated line running to the interior unit was a little frozen up, but I don’t think it was too bad when I turned off the AC. But I’m hopeful if it’s not a thermostat issue, (they are probably 20 years old) that the parts will be covered under warranty from Carrier at least. Any tips on finding a good AC guy and not getting screwed?