Central air conditioning failures are a common occurence. Our experts have provided an explanation of the most common causes as well as the best methods of repair.
- Adjustable wrench
- Drill/driver – cordless
- Insulated screwdriver
- Needle-nose pliers
- Nut driver
- Socket/ratchet set
- Voltage tester
- Compressed air
- Condenser fan motor
DIY Air Conditioning Service Repair
When your central air conditioning system breaks down during a heat wave, you could be left waiting for days or even weeks for a repair technician. Not only that, but it could cost you a couple hundred dollars to fix. If you rely on air conditioning to cool your home, this could spell days of discomfort and an unexpected bill.
Instead of spending hundreds of dollars on a professional, you can save a lot of money by repairing your air conditioner yourself. Although it may be challenging, it is doable as long as you are comfortable working around electricity. Plus, it’ll only take about two hours out of your day. We consulted with local HVAC repair technicians to get their input on the best do-it-yourself AC fan repair and maintenance tips. These tips will be helpful for the most frequent “low cooling” and “no cooling” issues. You will need a few basic tools for this.
In order to complete this project, you will need a few tools that you may already have lying around the house. A multimeter, voltage detector, and an assortment of insulated screwdrivers and sockets will do the trick.
If these AC repairs don’t work, don’t worry. You’ve covered the most common failures and your service guy can now focus on finding the more difficult problem. In addition, with the new parts, you can expect years of breakdown-free air conditioning. To get started, follow these steps.
Why Is My Air Conditioner Not Cooling the House?
Make Sure the Problem Isn’t the Furnace
In order to fix your furnace, set your thermostat to AC mode and lower the temperature setting. If the furnace fan kicks in, this means that the problem isn’t with the furnace. However, if the fan doesn’t run, try resetting the furnace circuit breaker. If the fan still won’t start, it’s time to call a professional.
Caution: Turn Off the Power
In order to complete this safely, you will first need to turn off the A/C and furnace breakers in the main electrical panel. Once you have done that, you can use a voltage tester on the wires coming into the contactor. This will verify that the power is, in fact, off.
AC Doesn’t Work? Buy Parts
The AC contactor (relay) and start/run capacitor(s) (as seen in the illustration below) are the parts that fail most often, and they are inexpensive. Therefore, it would be a wise decision to buy and install those parts right away, especially if your air conditioning service unit is five years or older. The condenser fan motor can also fail, but it would cost around $150 — you may want to wait to buy that unless you are certain that it is the problem.
In order to purchase replacement parts, you will need to find the nameplate on the condensing unit (not your furnace). Once you have locate the nameplate, make a note of the make, model, and serial number (or take a photo). After you have gathered this information, you can then purchase the parts from an appliance store, furnace dealer, or online.
Project step-by-step (8)
Learn the Anatomy of a Central Home Air Conditioner
Shut Off the Power
- The first step is to open the electrical box next to the condensing unit. Once you’ve done that, you can pull the disconnect block out.
- A voltage sniffer can help you to check if the power is really off inside the box.
Clean the Condenser Coils
Cleaning your air conditioner condenser is important for maintaining your AC unit and making it last longer. To clean your condenser, start by turning off the power to the unit. Next, remove the fan cage so you can access the coils. Use a garden hose with a spray nozzle attachment to rinse the coils. Be sure to remove any debris that has accumulated around the unit.
- Aim your garden nozzle upward into the top of the condenser coil to remove any crud buildup below the lid.
- Work the full length of the coil and then aim the nozzle down and flush the debris down the coil fins.
- Adjust the nozzle to a gentler stream and shoot water directly into the coil to flush out any remaining debris.
Test the Fuses
How to Check Fuses In the Disconnect Block
- Set your multimeter to the lowest Ohms scale and touch the red and black leads to opposite ends of each fuse.
- If you get a numerical reading, the fuse is good.
- A zero, a minus symbol, or an infinity symbol (∞) on a fuse indicates that the fuse is blown.
Inspect the Inside of the Access Panel
As you follow the electricity line to the house, you will see a layer of insulation. After that, you will see a series of electrical conduit. It is important to check for rodents’ nests or evidence of chewing on wires and electrical connectors before replacing any parts.
How to Discharge a Dual Start/Run Capacitor
- Remove the capacitor from the retaining bracket.
- Gently touch the insulated screwdriver to the HERM terminal, and then touch the COMMON terminal.
- In order to get your fan running smoothly, you will need to connect the FAN (or “F”) terminal to the “C” terminal.
- Single-mode capacitors can be shorted by connecting the two terminals.
Replace the Start/Run Capacitor(s)
All air conditioning service units have at least one capacitor. The capacitor’s purpose is to store electricity and release it during compressor and condenser fan startup. This provides both motors with an extra jolt of power. Additionally, the capacitor smooths out voltage fluctuations to protect the compressor and condenser fan motor from damage.
Capacitors usually fail gradually over time, providing less startup power each time, but they can also fail in an instant. If gradual capacitor failure goes unnoticed, it can stress the compressor and condenser fan motor windings, leading to their early failure. To avoid this, it’s best to replace your capacitors every five years or so.
How to Replace a Capacitator
- Before you disconnect anything, it is important that you take a photo of the wires. This will serve as a reference in case you need it later on.
- To discharge the stored energy in the old capacitor, follow these steps.
- To replace the capacitor, you will need to use 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 in order to create a secure connection.
- Before moving on, you need to make sure each connector is tight. To do this, wiggle each one. If it’s not tight, remove the connector and then use your fingers to bend the rounded edges so it fits more snugly on the tab.
- Make sure that when you’ve swapped out all the wires, you secure the new capacitor tightly. This will ensure that your device works properly.
WARNING: It is important to discharge the capacitor before making any changes, such as removing it from its bracket or disconnecting wires.
Replace the AC Contactor
The AC contactor is a relay that, using low-voltage power from the thermostat, switches 220-volt current to the compressor and condenser fan. Even if your AC contactor is working, it pays to replace it every five years or so to be on the safe side. Unscrew the old AC contactor before removing the wires. Then, once the wires are removed, you can put the new unit in place.
- In order to install the new contactor, you’ll need to remove a connector from the old one and put it in the same spot on the new part.
- Use a wrench to tighten the connectors where needed.
- The new contactor should be secured in the condensing unit.
How to Test Your Repairs
- The next step is to reinstall the access panel and disconnect block.
- Turn on the breaker package, then set the furnace to a lower temperature, and wait to see if the AC starts.
- The compressor should always be fully engaged and the fan should always be fully moving at the right speed.
- If the compressor starts but the fan doesn’t, the motor most likely needs to be replaced.
- Turn off the power and remove the screws around the condenser cover.
- Remove the cover and place the fan blade and motor back in place.
- ReInstall the blade and secure the cover.
- And then repower the unit and see if the fan starts.
- If it doesn’t, you’ve given it your best shot—it’s time to call a professional.
- Replace the fan motor in air conditioner
Be Patient at Startup
AC units and thermostats: these devices allow you to turn the appliance off, then power it up again. However, the unit can take up to twenty minutes to turn back on. And, if you’ve subscribed to an energy-saving device. If you have installed the parts shown and rebooted the circuit breaker, re- neurologicalized the switch at the furnace, moved the thermostat to AC mode and lowered the temperature below the indoor temperature, and the unit doesn’t turn on after 30 minutes, then it’s time to call an expert.