How to Repair the Most Common Air Conditioner Problems Yourself

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.

Introduction

Our experts will show you some easy DIY solutions for the most common central air conditioning repairs. You’ll be up and running again in no time and save the expense of a service call.

Tools Required

Adjustable wrench
Drill/driver – cordless
Insulated screwdriver
Multimeter
Needle-nose pliers
Nut driver
Socket/ratchet set
Voltage tester

Materials Required

Capacitor
Compressed air
Condenser fan motor
Contactor
Fuses

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.

The next thing you should do is check the outside condensing unit. The compressor (which sounds like a refrigerator) and fan should both be running. If they’re not, you can find the troubleshooting and repair procedures shown here.

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)

Step 1

Learn the Anatomy of a Central Home Air Conditioner

The central home air conditioner is a system that many homeowners rely on to keep their homes cool and comfortable during the warmer months. This system contains two main parts – the condenser, which is located outside of the home, and the evaporator coil, or the A-coil, which is located in the plenum of the furnace or air handler. The refrigerant inside the A-coil is responsible for carrying the heat from the home to the outdoor condenser unit. The condensing unit’s fan is responsible for blowing outside air through the condensing coil to rid of the heat. If any of the three parts housed in the condensing unit need replacing, it’s a job that can be done by a DIYer. These parts are the AC contactor, the start/run capacitor(s), and the condensing fan motor. The condensing unit also contains the compressor, but that’s a replacement that should only be done by a professional. The A-coil doesn’t have any parts that can be serviced by a DIYer.

Step 2

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.

Step 3

Clean the Condenser Coils

Bestamericanheatingandcooling-clean condenser coils on air conditioner

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.

Step 4

Test the Fuses

Many disconnect blocks contain two cartridge fuses. If you’re having trouble disconnecting a higher amount of power than you have seen your other devices before, it might be time to check your disconnects. There will never be a simple solution to any problem. If you replace the parts, install new fuses, fire up the unit, call a pro, you’re bound to jump back to the problem when it blows again.

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.

Step 5

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.

If you find broken wires or chewed insulation, you will need to take care of a few things before you can safely handle any repairs. To start, you will need to discharge the capacitor. This can be done by shorting the terminals of the capacitor with a jumper wire. Once the capacitor is discharged, you can repair the wires and clean out the nest. If electrical repairs are not your forte, it is best to call a pro.

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.

Step 6

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.

Step 7

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.

Step 8

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.

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