Sweltering temperatures are here or just around the corner, and your best defense is a central air-conditioning system. If you have one at your house, here’s what you should do to make sure it’s tuned up and ready to go.
Before you start tinkering with your central air-conditioning system, it’s important to understand the basics of how it works. The system consists of three main parts: the condenser, the blower unit and the ductwork.
The condenser is the large outdoor unit that is probably tucked behind your garage. Its role is to manage the temperature of the refrigerant, usually Freon, which travels back and forth from the house. The condenser does this by pressurizing the Freon gas as it arrives, turning it into a high-temperature liquid. The Freon in its new state then travels back to the house and to the blower unit.
Once it enters the blower unit, the Freon is changed into a gas and becomes dramatically colder. This cold gas then gets piped through a coil in the ductwork. Air blows through the coil, which is how it cools down before it continues into the house. The blower unit is constantly pulling air from the house through return ducts, forcing it through the cooling coil and then back to the house through supply ducts. Once the Freon has done its job, it travels to the condenser, where it is pressurized back into a liquid, and the cycle starts again.
You should leave some of the more delicate parts of the system, such as the refrigerant lines, to the professionals. But there are easy things you can do to maintain the system, particularly before summer heats up.
Change the filters
These are located at the blower unit and are usually placed where the return duct meets the unit. You should check your filters once a month. A badly clogged filter slows down the airflow through the blower unit, allowing the cooling coil to ice up. This could cause your unit to shut down.
Many grades of filter are available. If you use the kind that reduces allergens, know that they’re going to clog up faster, so they should be checked more often.
Check the condensate-removal system
When warm air passes through the cooling coil, condensation occurs. Air-conditioning systems have a variety of ways of dealing with this. Depending on where your blower unit is located, this moisture may go into a gravity-fed drain, or it may go into a pan under the blower unit. If it’s in a basement, the pan may have a small pump to move the water to a drain. If the unit is in an attic, the water may just enter the pan and evaporate.
If you have a pump, test it to make sure it’s functioning properly. It likely has a float attached to it that engages the unit; move the float up and down to see if it works. If you don’t have a pump and there is no drain in the pan, check to see if there is a kill switch. This is a wired water sensor set to a certain height in the pan. If water touches it, the system shuts down. If your unit is in the attic, pay particular attention to testing the kill switch — you don’t want the pan to overflow and have water dripping on your ceiling.
Clear the debris
For the exterior condenser to work properly, it needs a nice, unobstructed flow of air around it. Make sure that there is at least 2 feet of clear space around the unit, free of shrubs, wood piles and low-hanging branches.
The condenser’s fan spent all of last summer sucking in air, leaves, debris and pollen. So give the unit a spring cleaning. For this, it’s best to wash it with a garden hose. If things look really gummed up you could use a chemical cleaner, but those are harsh and usually unnecessary.
Check the ductwork
First, check the registers in your house. Make sure that no rugs or furnishings obstruct the airflow. Then open them up and see if anything has gotten into the ductwork that could cause problems. If you have toddlers around, it’s anyone’s guess what’s in there.
If you find mold growing in your ducts, contact a duct-cleaning company. For a little cash, they can thoroughly clean your entire system.
Next, check the ductwork that travels through your attic or basement. All of the connections and seams should be sealed, and the ductwork should have no holes or corrosion. To cover any holes and seal the joints, use silver aluminum-foil tape, as opposed to the traditional duct tape.
If you have an attic system, pay close attention to the insulation on the supply duct — the one that brings the cool air back to your house. With no insulation, that cold metal will start to sweat in your hot attic and the condensation will drip onto your ceilings.