When temperatures are hitting the high 90s, the last thing you want is for your AC to sputter out. A few hours without air conditioning will turn your house into a sweatbox, leaving you and your family hot, cranky and uncomfortable. It’s generally a good idea to have a professional over to look at your AC unit; however, there’s often plenty you can do to troubleshoot – and even fix – minor problems. In the hopes of keeping you all cool and comfy this summer, here’s a handy guide to some common problems and the best ways to fix them.
Basic Troubleshooting
1. If your AC doesn’t turn on
If your heat and air conditioner doesn’t kick in automatically, first make sure that it’s set to cool, and then turn the set temperature well below the current room temperature. Next, make sure that both your cooling and heating system and the outdoor condenser are switched on. A 240-volt disconnect switch should be mounted on the house near the compressor.
Check to see if that has been switched off. Finally, check your main electrical box to make sure that there are no blown fuses or tripped breakers. If you’re unable to locate the problem, turn off the power to your AC and call in a technician. Your thermostat or compressor may be faulty, and you should have a professional take a look at it.
2. If your AC doesn’t cool
If your AC unit is running fine but not cooling your house, it might just need a good cleaning. It’s important to check your owner’s manual for specifics, but cleaning your AC is a fairly simple 
process. Start by shutting off power to the unit. It’s a good idea to also shut off the AC’s 240-volt circuit on your home’s main electrical panel. Clear any debris or brush that has grown up around your compressor and move anything that might be inhibiting good air flow.
Remove the protective grilles and the main cover from the compressor, being very careful not to loosen any wires inside. Then, gently brush dirt and debris from the fins using a soft brush. Taking care not to damage the fins, clean them carefully with a vacuum cleaner. If your manual suggests lubricating the motor, this is a good time for that as well.
Put everything back together, and give it a test run. Turn the thermostat off, switch the power back on at the main panel and at the disconnect switch, then wait five minutes or so before turning the thermostat back on (this will prevent strain on the compressor). After it’s been running for a few minutes, touch the two tubes that run from the condenser to the air handler. If one is warm and the other cool, you’re good to go. If not, call in a tech.
3. If water is pooling around your AC
Heating and cooling systems produce a lot of condensation, but it’s usually drained away through a plastic tube to a drain or a condensate pump. If there’s water pooling near your AC, either the water flow through the tube is blocked, or the pump might be broken. First check to make sure that none of the tubes are leaking. If you find a leak, replace the tube.
If your AC uses a condensate pump, you can test if it’s working by pouring a little water into its pan. If the pump doesn’t kick in, check if it’s plugged in and if it’s receiving power. If that doesn’t work, your pump needs to be repaired or replaced.
If the pump is running fine but the pan doesn’t empty, there may be a blockage somewhere along the line. Remove the check valve, loosen the little ball inside, and clear any algae or obstructions. If there’s ice built up, the filter might be dirty. If the filter’s fine, call an AC technician because your refrigerant may need to be refilled.
