A condenser fan is part of a heat pump or central air conditioning system that circulates air across the system's condenser coil to increase the transfer of heat. Though some condenser fan motors have sealed bearings, others need lubrication. In either case, though, fan functionality is vital, as the failure to maintain proper air flow can not only minimize the system's efficiency but can cause the system's compressor to fail. In an air conditioning system, the condenser fan's role is really best explained by this simple fact: If the fan isn't working, the device won't cool anything.
Types Of Condenser Fans
Fan blades are essentially the same, so what's really being discussed when talking about condenser fan replacement is the driving force of the assembly--the motor. Motors are gauged by varied horsepower, voltage and rotations per minute. Normally set up in a direct drive to the blade, condenser fans range from low-fractional horsepower in small residential units to more than 1 horsepower motors for large-scale commercial use. These fan motors can also come with an open-bearing or closed--also known as sealed-bearing--structure. The latter setup has no oil ports or oil port plugs. An additional consideration is whether the shaft is pointed up or down, which varies among models. Motor diameter is another variable that must be considered when buying or replacing the fan component.
Repairing Or Replacing A Condenser Fan
To minimize the need for repairs, it's a good idea to check the fan motor to make sure the fan functions, preferably in late winter or early spring. To do so, shut down the entire condensing unit at the electrical disconnect box, set the thermostat to cool, and then restore power. Observe the unit to make sure the fan is turning and blowing a sufficient flow of air. As noted above, if the fan isn't working, the device simply won't cool the air.
First, check if the fan is somehow being impeded. Try to get some oil, such as WD-40, with a plastic extension to get the oil into the bearings and aid the mechanism. If that doesn't work, the fan motor will likely need to be replaced. Earlier we mentioned the possibility of damage to the compressor if the fan fails. If it's hot out and the fan motor fails, the unit will stop cooling and pressure within the condenser can rise to such a degree that it's shut down by a compressor overload switch (though not all units are equipped with this feature, something work checking when buying a new unit). If there's a problem, checking the fan will enable you to replace the fan cheaply as opposed to the costly expense of replacing the entire compressor because it blew when overloaded.
Now, should you decide to repair the fan, there are a few considerations. Most important will be the matching of the component traits mentioned earlier with your replacement. An error there could lead to your new motor--or worse your heating or cooling system--burning out. But also make sure the existing bracket will fit the new motor. If not, a new bracket will be needed, in which case the diameter of the existing bracket will need to be measured. For the actual replacement, follow the two wires coming out of the motor toward the main terminal block and remove them, ideally using a set of needle-nose pliers. Remove the mounting screws for the fan assembly and carefully withdraw the assembly from the motor comportment. A thin nut will hold the fan blade to the motor, which should be removed so the fan blade can be used with the replacement motor. Attach the mounting bracket to the new motor and reinstall the fan blade, which should have a rubber washer. Reconnect the wires from the main block, and reattach any protective covers for the assembly. Note that for any A/C or heating unit, at least 2 feet clearance should be maintained around the unit for proper air flow.