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Re: My outside a/c unit fan stopped working. When I
By saying the condenser fan is not working as well, I have to ask is
the contactor making any kind of noise?. If the contactor is not making
noise, look for some smaller wires going to the contactor. These are
the low voltage wires that send 24 volts to the contactor. Make sure
the thermostat is turned on, set it for a temperature lower than the
current room temperature. Are you getting voltage to the contactor? If
the answer is no check the W wire at the air handler and at the
thermostat. The G wire runs the inside blower only. This is why you can
put the fan in the ON position and not have the compressor running all
the time. If you are getting voltage at the contactor turn the power
back on at the compressor, take a sturdy insultaded rod, very dry wood
or plastic remember electricity can kill damp wood can conduct
electricity. Look for a small bump in the center of the contactor.
Press it with the rod and see if the compressor turns on. If it turns
on when you press this point on the contactor and off when you release
it then the low voltage side of the the contractor is bad. If the bump
is pulled in and the unit is not running take the multimeter and
carefully check to see if your are getting 240 volts across the two
bottom connections and then 240 volts across the top of the
connections. If you are getting 240 volts on one side only the the
contactor is bad and you need a new one. Turn off ALL POWER this is the
breakers for both the compressor and the furnace. Again make sure the
power is off. Make a diagram of the wire positions, then disconnect
them. Remove the contactor and take it to an electrical supplier or an
HVAC parts supplier and get a new one. Reinstall it and reconnect the
wires. Turn the power back on and everything should be working again.
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The bearings are bad in the motor and after the fan runs enough it eventually gets hot, making the bearing screech and the fan locks up. Need to replace motor again. See if it has a warranty. The reason it gets hot is because the fan is what removes the heat from the coil and if the fan isn't running there is nothing to cool it off so to speak.
What voltage is the unit it could be the capacitors for the fan motor is bad or a bad fan motor. my guess is the humming you are hearing is from the compressor. There should be two copper lines going to the unit feel the temperature with your hand and see if the bigger one is cold. If it is it means your compressor is making that humming sound. but i need more info. could be a number of things bad contactor.
Hello Sounds like the condensor fan motor is going bad.If the fan stops turning or is not turning at full speed, the compressor can not give off heat to the condensor.Which will cause it to shut down on high heat.
So i would start with a new fan motor.Your local heating and cooling supply house should have these in stock.
It sounds like the unit may be over charged. Make sure the outside coils are clean and you have plenty of airflow coming out of the top of the outside unit. What could be happening is, when the temps get higher outside, so do the pressures in the system. The compressor has a thermal overload protection that will kick the compressor off if it gets to hot, which if the compressor is over charged, it will work twice as hard, over heat and shut off. You would need a technician to come out and get the refrigerant charge back to normal. Another thing that could be happening is a weak or faulty capacitor, which is a small round or oval metal object, found in the electrical compartment on the unit. This are fairly simple to change out if your comfortable with electric. I've also had to put what's called a hard start kit on compressors with the same problem, new and old. The hard start basically gives it that extra boost of power to get it up and going. I would start with the refrigerant charge and go from there. The electrical "humming" sound that you hear unless you turn the breaker to the furnace off, is the contactor on the outside unit having a call for cooling. The 24 volts come from the furnace, to the outside unit, and pulls the contactor in to power the unit with the 220 volts supplied. It is normal and you don't have to worry about that at all. I hope some of this helps and good luck!
When you shut it off and back on it slugged the compressor if you turn it off and back on before the pressures equalize between the high and low sides it will slug the compressor and it will not run should let sit for five minutes or so before restarting. The humming is either the compressor making noise usually common for the compressor to make some noise or the fan motor bearings are getting bad on the outside unit. If the unit works normal probably not much you can do till it breaks if it is the compressor it is more economical to replace the whole unit if it is just the fan motor it is worth changing. You could take an amp draw on the fan motor and the compressor to see if the are within the limits on the name plate of the outside unit.
Even when the power is off at the unit outside the thermostat will supply power to the contactor of the outside unit. This may give a hum or buzz as you stated. If when the power is on to the outside unit the fan tries to start but only hums the motor may be bad. Does the compressor start and run?