The ac was working fine for the beginning of summer. The thermostat has been set to auto cool. Suddenly, the house filled with a funky odor, then a burnt plastic smell. I realized the thermostat was trying to kick the ac on (could hear clicking and humming) but no air was blowing through the vents. I turned of the thermostat, but the humming continues. A repairman came out today and checked the filters and all the vents for clogs- none. Then he checked the thermostat- it seemed fine. Then he found water leaking from the pump, which is attached to the unit. He cleaned the pump (lots of muck), and then cleaned the pan and the drain line. The humming only stopped when he unplugged the unit. He replaced the circuit board with a universal board and said he had to rewire the unit. At that point, cool air started blowing again... But when the thermostat was turned off, the motor kept humming. He said he wants to come back tomorrow to replace the motor. He turned it on before he left and said I could leave it on, but before we left the basement, the lights flickered and there was a pop and a burnt smell. He unplugged it and said the wiring at the plug was bad and causing reverse polarity. Wouldn't that have kept the unit from working properly before? He seems hesitant but wants me to pay extra to rewire the outlet to the breaker. Is this a fix or a fishing expedition? Help!