Marshfield, Mo. – Triple-digit heat has home air conditioning units working overtime. Simple maintenance can help keep an air conditioner running smoothly when it’s needed the most.

A homeowner can easily do some maintenance; other jobs will require a heating/cooling professional. Call a professional if it’s been several years since the cooling system was cleaned or serviced, recommends Robert Schultheis, natural resource engineering specialist for University of Missouri Extension.

“Not only can they add refrigerant, find leaks and fix worn parts, they can also show the homeowner the things to do to extend the life of the system between service visits,” Schultheis said.


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Outdoor Unit

Check the condenser fan blades, or fins. Schultheis said those blades must spin freely to blow the hot air away from the unit. Bent or debris-covered blades can tax the A/C system.

“You may have to remove a screen or panel to be able to straighten or clean those blades. But, be sure to shut-off power before opening the unit,” Schultheis warns.

Trees and shrubs sometimes grow too close to an outdoor unit. Schultheis suggests cutting plants back to keep 2-3 feet of open space around the unit and 6-8 feet above it. This prevents overloading the A/C unit.

“It needs to intake air and get rid of heat,” Schultheis said. “Plants growing too close will restrict that important airflow.”

While designed to work in direct sun, providing some shade for the condenser unit will have a small benefit.

“The efficiency will improve a bit if the unit is shaded,” Schultheis said. “Whenever possible these units are located on the north or east side of the building so they get shade from the intense afternoon sun.”

Avoid blowing lawn clippings at the condenser when mowing the grass. According to Schultheis, lawn debris can collect on the cooling fins or block screens and panels. This will decrease the efficiency of the unit and make it work harder to cool the home.


Indoor System

Change the blower filter regularly. A fresh filter helps keep indoor air cleaner and reduces dust and dirt damage to the blower or evaporator coil. Schultheis said there are four basic types of filters.

  • Fiberglass – inexpensive and disposable, but do a poor job filtering
  • Pleated – disposable, cost a bit more and do a better job
  • Metal-mesh or non-metal fibers – can be cleaned and reused
  • Electrostatic or electronic-air cleaner filters – most expensive and effective

The thermostat needs attention too. An older, bimetallic thermostat can behave erratically if the contacts get dirty.

“Remove the cover and make sure the contacts are clean and dust free,” Schultheis said. “Sliding a clean piece of paper between those contact points will rub off any dirt. Don’t use sandpaper, it’s too abrasive.”

Thermostats that use mercury in a sealed bulb need to be set up properly, Schultheis said. Detach the cover and make sure the bulb is level so it will turn on and off at the set temperature.

Some homeowners will set the thermostat high when no one is home, to save energy. A full day of triple-digit temperatures can make the inside of the home too warm if the thermostat is set high. A programmable thermostat can solve this problem.

“You can program them to change the temperature automatically, so you can save the energy when you’re not there. It will pre-cool the home so it feels comfortable when you return,” Schultheis said. “An investment in a programmable thermostat can pay for itself in less than a year”

These simple, do-it-yourself steps can help keep the A/C working properly. Schultheis said preventative maintenance always saves money. Ignoring small things until they become big problems often leads to large repair bills.


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