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check for a failed start/run capacitor for the motor
if the motor spins freely then the humming will be a frequency hum because there is not enough power to start the fan running
the extra current will blow a cb
Hi, This being 18,000 BTU is a 240 volt unit. The electronic in it work at 120 volts. I believe you have only 1/2 the electrical current going to it. Thus the Hum. CHECK YOUR FUSES OR CIRCUIT BREAKER! A 240 volt circuit breaker has two sides or switches with a bridge between them. One of them may be tripped. Shut off the breaker wait a few seconds then turn it on so that the it engages all the way. It if clicks or pushes your fingers back and prevents you from engaging it, there is a problem likely with the compressor/fan or it's wiring, and it is drawing too much current and requires repair or replacement.
the constant hum is probably the contactor which may be pulled in on the 24volts check your capacitor that is most common to go out its a canister either oval or round it has wires going in to it please give me a vote and rating
Hi, something is for sure still energized after it is satisfied. I would think it would be on the control voltage side, like a contactor coil or relay. What I would recommend if you are able, is to go up top to the condenser and remove the cover. With the unit satisfied at the stat, listen to see if you can find the componant that is still getting power to it and you will know. If it is nothing above, my guess it would be in the controls on the indoor unit. More then likely, I would say you will find your problem part up top. Please keep me posted on this. Let me know what you find. Something is still getting power to it. With the unit satisfied, am I right to say the hum is not coming from the breaker its self? Just asking. Sincerely, Shastalaker7
yes the start capasitor starts the fan motor and the contactor pulls together when the t-stat tells it to start and it has a spring in it that gets week , some brands of units have a delay in the outside units board to stop it from starting at the exact same time as the airhandler
Ifs its a small humming sound,then its the contactor pulling in. But if it a loud humming sound then its the compressor kicking in. and the fans not, try to take something long and turn the blades on the fan, if it takes off and run then your capacitor is shot or swollen at the top,which was cause by power surge. Take-off and replace with the same mfd. writings ,on the outside of can. Also check for blown fuses or tripped breaker . the fuses should be in the disconnect box on the wall, or the breaker in the breaker box.. Older house has fuses instead of a breaker box!
Blank screen sounds like a fried thermosat. Abrupt outages can affect certain types of thermostats. Make a jumper wire and jump across R and G. See if you get any action from anywhere. If a fan or compressor kicks in you know you have a burned out thermosat...