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3 Potential Reasons Your AC's Condenser Fan Spins Slowly

Stand beside the condensing unit outside your house while your central air conditioning is running, and you should normally hear the quick whirring of a motorized fan. The fan is an essential part of the unit, as it helps keep the temperature of coils low and equalized while the coils transform refrigerant fuel. A fan that goes out can overheat your system and shut down the entire unit. A fan that spins slowly can make your unit far less efficient at cooling your home.

What are some of the possible causes of a condensing unit fan that's spinning slowly?

Trapped Debris

The fan can cool the coils due to incoming air that passes through the grated condensing unit cover. The grated cover can also occasionally allow in debris. If the debris gets stuck in or on the fan, the debris could potentially slow the fan down to a crawl or end up stopping it completely.

You can check this problem for yourself by first pulling out the fuse in the box next to the unit so there's no electricity on. Look for a raised grated dome that protrudes from the case itself. That's the fan guard. Remove the screws holding the guard onto the unit and then flip the entire guard over.

The fan and motor assembly are attached under the guard with the fan at the bottom so flipping it over puts the fan at the top. Look for any leaves or small branches that could have become trapped in the blades and remove. Examine the fan for signs of bends that could also cause a slowdown, and also means that you need to buy a new fan.

You should also try spinning the fan manually with your hand to see if it spins freely. If it does spin freely, you might have an issue with the motor or capacitor.

Broken Motor or Capacitor Issue

A motor that's on the verge of death or that is starting to lose its bearings can slow down the progression of the fan. There's no real fix for a broken fan motor so it will need to be replaced. Call in an air conditioning repair service to both examine your current motor and to issue a replacement, if necessary.

If you have a multi-meter, you can first check to make sure the run capacitor isn't the issue. The run capacitor essentially helps the unit keep a constant electrical current during operation. A failed capacitor can disrupt the power supply and lead to a lackluster fan speed.

Make sure you drain the stored electricity in the run capacitor using an insulated screwdriver before testing. Set your multi-meter to ohms and then check that the reading matches the number listed on the side of the capacitor. If the numbers don't match, you need a new capacitor.

For more information, contact Affordable Comfort Heating and Cooling or a similar company.