The troubleshooter's guide to air conditioners

Keeping cool in the summer is hard enough without a broken air conditioning unit. With the right knowhow, you could spot the problem and get back to staying cool much faster.

•  Central air conditioners work best when the area around the outdoor unit is kept free of debris.
• Trim bushes periodically so that they're at least two feet away.
• If you have any trees nearby, you'll have to keep the grills cleared of leaves in the fall. Consider removing tree branches that cause problems.
• When mowing, bag the clippings when you're near the unit or direct them away from the unit.
• Cover the unit during snowy weather.

• Refrigerant lines connect the evaporator coils inside the house with the condenser unit outside. The pressurized refrigerant circulates through the two units.
• Have the refrigerant level checked every other year by a certified service person.
• Low refrigerant levels cause poor cooling or make the condenser run continuously.
• If you find oily spots on or near the refrigerant lines, or hear a hissing sound, refrigerant may be leaking. Call for repair immediately.

If an outdoor unit makes a clanking noise while running, following these steps could help you discover what's wrong:

1. Shut off the power to the unit and turn up the thermostat.
2. Remove the grill and check for any obstructions that may be hitting the fan blades.
3. Check to see if the fan is loose. It should spin freely without wobbling.
4. To tighten, use an adjustable wrench or a hex wrench.
5. If your fan motor has oil ports (usually plugged with rubber or metal caps), add a non-detergent lightweight SAE 20 oil. Use no more than 10 drops per port (or check your owner's manual).
6. Tighten any loose screws in the housing.
7. If the noise continues, call for repairs.

• If the unit won't turn on, check to see if the circuit breaker is tripped or the fuse is blown.
• Make sure the unit is switched on and that the thermostat is on the Cool or Auto setting.
• Set the temperature below the room temperature. If it still won't run, call for repair.

House air conditioners are built to function when the ambient temperature requires cooling to be comfortable. If the outside temperature is below 15°C, operating the unit could cause serious damage to the compressor.

• Central air conditioners should be covered in winter. Window units can be covered while still in the window.
• Make sure to use breathable material for the cover. Plastic tarps keep moisture out, but they also keep it trapped inside, which can result in rust and early unit failure.
• Your manufacturer may sell a suitable cover to fit your unit.

There's almost nothing worse than a broken AC unit on a hot day. But if you know what to look for, you could have it up and running much faster.