Air conditioning and heating maintenance

Maintenance-wise, just change the furnace filters monthly, hose off the exterior unit periodically to remove dust and debris, and most importantly, call a licensed heating/cooling contractor every spring for a thorough inspection and comprehensive maintenance.

If your air conditioner seems dead, or if it is blowing only hot air, check the circuit breakers before you call for service. Nothing makes you feel more stupid than paying a serviceman $75 to flip the breaker back on.

Buy the right capacity unit. Measure the room you want to cool and bring the width, length, and height measurements to the store so that the salesperson can help you choose a unit that's efficient for the space.

Get a unit with an energy-saving thermostat that cycles the unit on and off.

Make sure you get a three-speed fan (high to cool the room quickly and medium or low to maintain the temperature).

Choose a model with a timer to turn the unit on before you get home.

Don't ever remove the cover and clean inside the unit. You could get a shock (even when it's unplugged), and all you can do is bend or break something. If you goof up something inside, all you'll have is an ugly doorstop.

• Checking the ducts for leaks- Take a step back from your forced air unit, and check the ducts for leaks. The ducts are used to distribute warmed air to various locations throughout the house.

If you see fuzz or feel air coming out through the joints between duct segments, seal them with metal tape (a new type of duct tape). Yes, you'll be using duct tape on ducts.

• Cleaning the blower compartment- Air will flow better if you take a minute to clean the blower compartment.

First, turn off the power to the forced air unit at the emergency switch. The switch may be mounted on or near the unit itself. If you can't find the switch, turn the power off at the circuit breaker or fuse box before sticking your hands anywhere near the inside of the unit.

Next, open the hatch on the front (if it isn't already open to change the filter), and use a vacuum cleaner with the upholstery brush attachment on it to remove any dirt, lint, and dust bunnies you find.

You can clean the burner compartment, too. Moisture from the air can cause the burners to rust. Use a wire brush to clean them. Then, use your vacuum's small snoot or the end of the hose. Carefully suck up the loosened rust, lint and debris lying around in the compartment and on the burner elements. Make sure the furnace is turned off and has had a chance to cool down before you start.

• There are two commonly used systems in San Diego houses:

• Electric systems: Use electrical resistance to generate radiant heat in baseboard units, or in cables embedded in the ceiling or floor.

• Forced air heating systems: Heats air as it passes through the furnace. A blower and a system of ducts take the warm air throughout the house, and then back to the furnace. Have a qualified, licensed heating contractor inspect and service your forced-air system every year before the heating season begins. This is not optional. Sure, you could save $75 by not doing it. But a dirty, inefficient furnace costs you ten times that much in wasted fuel. Even more important, a cracked heat exchanger or dislodged flue could fill your house with deadly carbon monoxide gas. We think you would agree that you and your family are worth more than what it costs to make sure the furnace is functional and safe.

When the furnace serviceperson does your annual service, dozens of maintenance tasks are performed (lubrication, burner adjustment, and so on) that help maintain your furnace's efficiency and keep it running for years.

Certain parts of your furnace may be difficult to locate If you do decide to do your own maintenance. For specifics, refer to your forced air owner's manual. SDG & E will give you a certain amount of support at no charge.

• Replacing the filter - Of the maintenance tasks you can do yourself, the easiest is replacing the furnace filter. It should be replaced every month during the heating season. If an air-conditioning system is part of the same system, the filter should be changed every month year round.

The filter takes dust, dirt, pollen, carpet fibers, and pet dander out of the air, which keeps the house cleaner and helps keep allergies at bay. Without all that stuff in the airflow, the blower motor lasts longer, too. The filter also prevents compressor coils (hidden within the system) from becoming clogged.

It may seem silly to replace the filter so often, but you would be surprised by how much airborne crud gets into your house. As a result, the filter gets clogged quickly, which makes the furnace work harder (it's like trying to breathe through a straw). And anyway, filters only cost a couple of bucks apiece. Clean the condenser coil fins on the exterior face at least once a year. Gently vacuum or brush the fins and then straighten any bent fins with a comb.

You usually find the filter near where the cool air enters the furnace -- in the cold-air return duct, or at the entrance to the blower chamber, or sometimes in both locations

After you find the filter, slide it out and replace it with a new one. Make sure the airflow arrows on the side are pointing the right way (toward the blower and away from the cold air).

Be careful not to disturb any of the small wires inside the furnace area. Most heating systems have low voltage controls and if you were to inadvertently disturb a control wire, the system may not come back on.