May home-maintenance checklist (© Garry Wade/Getty Images)

When the weather turns warm, follow the impulse to fling open the windows and let in the fresh air and light: The sun's ultraviolet rays are lethal to many harmful bacteria. May's the time to ready your home for summer.

Baby your cooling system
Before firing up your air conditioner, change or clean the filter. You'll want to change it every couple of months while the system is in use. The owner's manual will explain how to change filters and clean coils and fins in the exterior evaporator unit. With the air conditioning turned off, check the evaporator unit for dirt, brushing and dusting it. Trim any surrounding shrubs. Remove the pan from the bottom of the unit, clean and replace it. (Bing: How does an air conditioner work?)

Keep algae, mildew and mold from forming:

  • Central air conditioning units have a pipe that drips evaporated moisture onto the ground. If this clogs, water can back up into the house. Each spring, clean the line by removing the cap at the access hole on top of the pipe. Pour a cup of bleach into it, letting the bleach drain to the ground. If a clog has formed farther up the pipe, attach the suction end of a wet-dry vacuum to the pipe's end, wrap duct tape around the joint to create a temporary seal and run the vacuum briefly to remove the clog.
  • Window units: Stop the growth of algae and mold (and musty smells) by pouring two capfuls of bleach into the condensation pan (the drip pan located under the cooling coils). Do this monthly while you're using the air conditioner. Also, dust the unit regularly.
  • Evaporative coolers: Open the unit and remove the drip pan. Examine it for leaks or rust. Replace cooler pads each spring.

Put the furnace to bed for the summer
Check the furnace filter, holding it up to the light to see if it's dark and dirty and in need of a change. The instruction manual will tell you where to find these filters and how to remove and replace them. Vacuum the openings and grilles at heating and ventilation vents, registers and ducts.

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Service the furnace and air conditioner
The transition from cool to warm weather is the sign that it's time to take care of the appliances that keep you comfortable through the year. Call a professional to perform annual service on a furnace, air conditioner or evaporative cooler. Act early to book an appointment so you can avoid the summer rush. Call the company that installed the appliance or search online for licensed heating, ventilation and air conditioning specialists.

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Replace vacuum cleaner bags
Remove the vacuum cleaner bag outdoors so you don't release dust and allergens back into the house. Wear a bandana or dust mask to protect your lungs. While you have the vacuum cleaner open, dust it inside and wipe down the inside parts with a thin rag dipped in warm, soapy water and wrung out well. Keep water from the motor and electrical parts. Soak the vacuum tools in a bucket of soapy warm water, rinse and dry them. Let the machine air dry before installing a fresh bag and closing it up. Check the owner's manual to learn how often to wash or replace filters in some newer vacuum cleaners.

Vacuum refrigerator coils
Remove the front cover from the refrigerator and use the wand attachment on the vacuum cleaner to carefully suck out the dust and dried bits of macaroni and dog food that have worked their way under the fridge.

Store free-standing electric heaters
Dust, vacuum or wipe down their surfaces and check cords and plugs for fraying and loose wires before putting them into storage.

Wash windows
Cleaning all the windows and window coverings in your home is a big, satisfying and several-hours-long project. Choose a sunny day and, if possible, get someone to work with you.

Remove curtains and blinds if you can. Clean windows and window trim, inside and out. Start by brushing (with a dry broom) or dusting the trim. If it's really dirty, wipe it down with a rag and soapy water. Outdoors, use a hose to rinse off the soap. To clean the glass, use a good-quality squeegee, the tool of professional window washers. Before purchasing a squeegee, check the width of your smallest windows. Assemble a pole (unscrew the handle from a broom) that fits your squeegee's handle, a microfiber cloth and a bucket. Use a few drops of liquid dish soap or a teaspoon of TSP in a two-gallon bucket of warm water. Many professionals like TSP, or trisodium phosphate, a powdered stain remover and degreaser found at hardware stores, for a streak-free finish.

Caution using TSP: In a hot solution, it can remove or take the gloss off paints and can darken aluminum or wood.

Apply the cleaning solution with a rag or mop. Immediately squeegee it off, wiping the blade between strokes to minimize dripping. Do one window at a time. Use the squeegee on the pole for hard-to-reach places. Consider engaging a professional to do second-story windows.