Our experts shows you easy DIY solutions for the most common central air conditioning repairs. You'll be up and running sooner and will save the expense of a service call. Overview: Central air conditioner failures and solutions When a central A/C unit fails during a heat spell, you may have to wait days for a technician to show up, and you'll probably pay at least several hundred for the repair. But if you're comfortable and are willing to spend about $50 on parts, you can probably repair you air conditioner yourself in about two hours and save about $225 on parts We talked to local HVAC technicians to get their best do-it-yourself A/C repair and help you with the most common “low cooling” and need an inexpensive multimeter, a voltage sniffer, an and a socket set. If these fixes don't work, at least you've covered the most common failures, and your service guy can concentrate on finding

the more elusive problem. the new parts, you'll likely add years of Make sure the problem isn't the furnace Set your thermostat to A/C mode and lower the temperature setting. fan kicks in, the problem isn't in theIf the fan doesn't run, try resetting the furnace circuit breaker. still won't start, call a pro—the fixes shown here won't work. Next, check the outside condensingThe compressor (which sounds like a refrigerator) and fan should be running. If not, follow the troubleshooting and repair procedures shown here. Caution: Turn Off the Power Turn off the A/C and furnace breakers in the main electrical panel before pulling the outdoor disconnect or removing the condensing unit's access panel. use a voltage tester on the wires coming into the contactor to make sure the power The contactor (relay) and start/run capacitor(s) (see illustration below) fail most often and are inexpensive.

So it's a safe bet to buy and install those parts right away, especially if your A/C unit is older than five years. The condenser fan motor can also fail, but it runs about $150—hold off buying that unless you're sure that's the culprit. To buy replacement parts, find the nameplate on the condensing unit (not your furnace). Jot down the make, model and serial number (or take a photo). Get the parts at an appliance store, furnace dealer or online. Anatomy of a Central Air Conditioner Central A/C systems consist of two major components: a condensing unit that sits outside your house, and the evaporator coil (often referred to as an A-coil) that sits in the plenum of your furnace or air handler. in the A-coil picks up the heat from your home and moves it to the outdoor condensing unit. unit fan blows outside air through the condensing coil to remove the heat. The condensing unit houses the three parts replaceable by a DIYer: the contactor, the

start/run capacitor(s) and the condenser fan motor. condensing unit also houses the compressor, but only a pro can replace that. The A-coil has no parts that can be serviced by a DIYer. Start with the easy fixeswhite mold in ac ducts If you're getting little or no cold air, check these three thingshigh seer window ac unitsMake sure all the registers in the house are wide open.window unit air conditioners at lowes Then be sure the furnace filter is clean. Then go outside and clean off the condenser coils (Photo 2). If several registers were closed or the filter was clogged, the reduced airflow could have caused the evaporator coil to ice up and stop cooling yourIf you've changed the filter and opened all the registers

and you're still not getting airflow at the registers, deice theMove the thermostat mode switch from “Cooling” to “Off” and move the fan switch from “Auto” to “On.” blower run for at least 30 minutes or until there's good airflowThen turn the A/C back on to test it. If it works for the next 12 hours, you've solved the problem. If the condenser coils are clogged, the compressor can overheatYou'll experience intermittent periods of minimal cooling, followed by no cooling. Even if you're “sure” the condenser coils are clean, clean them again. Flip the A/C and furnace circuit breakers in your main electrical panel to the “Off” position. Next, turn off the power switch right at the furnace or air handler. Then yank the disconnect block (Photo 1) and clean the condenser coils (Photo 2). If the A/C still doesn't work properly after you've cleaned the condenser coils, installed a new filter and opened all the supply vents, proceed with the following repairs.

Many disconnect blocks contain two cartridge fuses. them before you proceed with repairs (Photo 3). A blown fuse is a sign of a failing part inside the condensing unit. replace it and think you've solved the problem. the parts we show here. Then install new fuses and fire up theIf it blows again, call a pro—you've got more serious issues. Inspect the inside of the access panel Follow the electrical conduit from the house—that's where you'll find the access panel. With the power off, remove and store the access-panel retaining screws and remove the panel. Before you replace any parts, check for rodents' nests or evidence of chewing on wires and electrical connectors. If you find broken wires or chewed insulation and can safely handle electrical repairs, discharge the capacitor first (Photo 4). Then repair the wires and clean out the nest. Otherwise, call a pro. Replace the start/run capacitor(s) All A/C units have at least one capacitor.

electricity and releases it during compressor and condenser fan startup to give both motors an extra jolt of power. smooths out voltage fluctuations to protect the compressor and condenser fan motor from damage. Capacitors can degrade slowly, providing less startup powerOr they can fail in an instant. can go unnoticed for a long time, stressing the compressor and condenser fan motor windings, resulting in their early failure. Since capacitors are cheap, it pays to proactively replace yours about every five years. Replacing a capacitor is easy. Just take a photo of the wires before disconnecting anything (you may need a referenceThen discharge the stored energy in the old capacitorUse needle-nose pliers to pluck one wire at a time from the old capacitor and snap it onto the corresponding tab of the new capacitor. The female crimp connectors should snap tightly onto the capacitor tabs. to see if it's tight. If it's not, remove the connector and

bend the rounded edges of it so it makes a tighter fit on theWhen you've swapped all the wires, secure the new WARNING: Discharge the capacitor before disconnecting wires or removing it from its bracket. A contactor is a $25 mechanical relay that uses low-voltage power from the thermostat to switch 220-volt high-amperage current to the compressor and condenser fan. A/C contactors can wear out and are at the top of the list of common A/C failures. Even if your contactor is working, it pays to replace it every five years or so. Unscrew the old contactor before removingThen move the wires to the new unit (photo 6). Reinstall the access panel and disconnect block. circuit breaker and furnace switch. Then set the thermostat to a lower temperature and wait for the A/C to start (see “Be Patient at Startup,” below). The compressor should run and the condenser fan should spin. If the compressor starts but the fan doesn't, the fan motor is most likely shot.