How to Fix Your Central Air Conditioner

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Home Improvement

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Central air conditioners consist of two components: the condenser and the evaporator. The condenser unit is usually located outside on a concrete slab, while the evaporator coil is mounted in the plenum or main duct junction above the furnace.

Most central air conditioners are connected to a home’s forced-air distribution system, meaning that the same motor, blower, and ductwork used for heating are used to distribute cool air from the air conditioning system. When a central air conditioner is running, hot air inside the house flows to the furnace through the return-air duct. The blower then moves the hot air across the cooled evaporator coil in the plenum and delivers it through ducts to cool the house. If the air conditioner is running but the house isn’t cooling down, the problem is probably in the distribution system.

Central air conditioners consist of two separate components: the condenser unit,
located outside the house on a concrete slab, and the evaporator coil above the furnace.

Both the evaporator and condenser are sealed, so a professional service person should be contacted for almost any maintenance other than routine cleaning. Central air conditioners should be professionally inspected and adjusted before the beginning of every cooling season. However, you can follow specific maintenance procedures to keep your system running efficiently.

Note: Before performing any work on an air conditioning system, ensure that the power to the system, both to the condenser and to the evaporator assembly, has been turned off.

Before you start working, try to narrow down the scope of the job. Look for the problem you’re having and its solution on the chart on the following page.

For more articles on home repair, check out the following links.

  • How To Repair Room Air Conditioners: Cooling units that you mount in your window have the same job as central air conditioners, but the repair principles are different. Follow these instructions to get your unit running smoothly.
  • Major Appliance Repair: If the a/c isn’t the only thing in your house on the fritz, you can learn how to fix other machines in this article.
  • Small Appliance Repair: Once you’ve tackled the a/c, a toaster or blender seems like child’s play. Find out how to fix them here.
  • Thermostat Maintenance: To make sure there’s actually a problem with your a/c, you may want to check the thermostat, too. Learn how to calibrate a thermostat.

Troubleshooting Your Central Air Conditioner

Central air conditioners will require some professional maintenance, but many minor problems can be easily fixed yourself. If your central a/c unit isn’t working properly, look for the problem you’re experiencing on this chart to see if it’s a do-it-yourself job.

If your central air conditioner is not working properly, use this troubleshooting chart to identify the possible cause and solution. The chart is divided into different categories, such as condenser problems and inadequate cooling. For example, if your condenser doesn’t run, it could be due to a lack of power, a faulty motor, or a faulty compressor. To fix the problem, you may need to check for blown fuses or tripped circuit breakers, call a professional, or replace the unit with a larger one. Another common issue is a dirty evaporator, which can lead to uneven cooling or inadequate cooling. If your evaporator is accessible, you can clean it once a year by removing the foil-wrapped insulation and access plate. However, if the plenum is a sealed sheet metal box, do not attempt to open it.

Materials Required
You should have these tools ready to clean the evaporator:

  • Screwdriver
  • Stiff brush
  • Large hand mirror
  • Household bleach
  • Wire

Step 2: Use a stiff brush to clean the entire underside of the evaporator unit. A large hand mirror can come in handy to see what you’re doing. If you can’t reach the entire area to clean, slide the evaporator out a little bit. The evaporator can be slid out even if it has rigid pipes connected to it, but be careful not to bend the pipes.

Step 3: Clean the tray below the evaporator unit. This tray carries condensation away from the evaporator. Pour 1 tablespoon of household bleach into the weep hole in the tray to prevent fungus growth. In extremely humid weather, check the condensate drain and pan every other day. If there’s a lot of moisture in the pan, the weep hole from the pan to the drain line may be clogged. Open the weep hole with a piece of wire.

Step 4: Put the unit back in its place, reinstall the plate, and tape the insulation back over it.

Step 5: Turn the air conditioner back on and check for air leaks. Seal any leaks with duct tape.

To ensure your air conditioning is working properly, you may also need to clean the condenser. Find out how to do this on the next page.

Cleaning the Condenser

In most air conditioning systems, the condenser unit is located outside the house and is susceptible to accumulating dirt and debris from trees, lawn mowing, and airborne dust. The condenser has a fan that moves air across the condenser coil. You must clean the coil on the intake side, so before turning off the power to the air conditioner, check which direction the air moves across the coils. Here’s how to clean the condenser:

Materials Required
You must have these tools ready to clean the condenser:

  • Grass shears or pruners
  • Spray bottle of coil cleaner
  • Soft brush
  • Fin comb
  • Carpenter’s level
  • Pry bar or piece of 2-by-4
  • Gravel or rocks

Step 1: Cut down any grass, weeds, or vines that have grown around the condenser unit as they could obstruct airflow.

Step 2: Clean the condenser with a commercial coil cleaner, which is available at refrigerator supply stores. The instructions for use are included. Flush the coil clean (do not use a hose) and let it dry.

Step 3: Clean the fins with a soft brush to remove accumulated dirt. You may have to remove the protective grille to reach them. Do not clean the fins with a garden hose, as water could turn the dirt into mud and compact it between the fins. Clean the fins very carefully as they’re made of light-gauge aluminum and are easily damaged. If the fins are bent, straighten them with a fin comb, which is sold at most appliance parts stores. A fin comb is designed to slide into the spaces between the fins. Use it carefully to avoid damaging the fins.

Step 4: Check the concrete pad on which the condenser rests to make sure it’s level. Set a carpenters’ level front to back and side to side on top of the unit. If the pad has settled, lift the pad with a pry bar or a piece of 2 x 4, then force gravel or rocks under the concrete to level it.

During autumn and winter seasons, it is important to shield outdoor condenser units from natural elements such as leaves and ice to avoid any blockages and damages. To do so, you can either use a commercial condenser cover specifically designed for the unit, or a heavy plastic sheeting that is secured with a durable cord.

If after cleaning the unit, you still do not receive cool air, the refrigerant may be the issue. Discover how to handle this problem on the following page.

Managing the Refrigerant

The refrigerant used in most air conditioning systems is called Freon. If the system does not contain the appropriate amount of Freon, the cooling will not take place or will be minimal. If you think there is a Freon problem, it is best to contact a professional to recharge the system. It is important to note that you should not attempt to charge the refrigerant lines yourself.

One way you can repair the coolant lines is by examining the lines that run from the condenser outside to the evaporator inside the house. If the insulation on the lines is damaged or worn, it can decrease the cooling efficiency of the unit and therefore should be replaced.

Replace any damaged or worn coolant line insulation with the same type of insulation as soon as possible and follow the manufacturer’s instructions for installation.

Now that you know when to seek professional help or make repairs on your own, you can save some money and enjoy cool air soon. For more tips on home repairs, check out the following links.

  • How To Repair Room Air Conditioners: Cooling units that you mount in your window have the same job as central air conditioners, but the repair principles are different. Follow these instructions to get your unit running smoothly.
  • Major Appliance Repair: If the a/c isn’t the only thing in your house on the fritz, you can learn how to fix other machines in this article.
  • Small Appliance Repair
  • Thermostat Maintenance: To make sure there’s actually a problem with your a/c, you may want to check the thermostat, too. Learn how to calibrate a thermostat.

FAQ

1. What are the common problems with central air conditioners?

Central air conditioners can experience a range of problems, including refrigerant leaks, faulty wiring, clogged filters, and broken compressors. It’s important to identify the specific issue before attempting any repairs, as some problems may require professional assistance.

2. Can I repair my central air conditioner myself?

While some minor repairs can be done by DIY enthusiasts, most central air conditioner repairs require specialized knowledge and equipment. Attempting to repair a complex system without proper training can be dangerous and may cause further damage to the unit.

3. How often should I have my central air conditioner serviced?

It’s recommended to have your central air conditioner serviced at least once a year, ideally before the start of the cooling season. Regular maintenance can help prevent major problems and prolong the lifespan of the unit.

4. What should I do if my central air conditioner isn’t cooling properly?

If your central air conditioner isn’t cooling properly, start by checking the thermostat settings and replacing the air filter. If these solutions don’t work, it may be a problem with the compressor or refrigerant levels, which require professional attention.

5. How can I prevent problems with my central air conditioner?

Regular maintenance is key to preventing problems with your central air conditioner. This includes changing the air filter regularly, cleaning the coils, and keeping the outdoor unit free of debris. It’s also important to have the unit serviced by a professional at least once a year.

6. Is it more cost-effective to repair or replace a central air conditioner?

The decision to repair or replace a central air conditioner depends on the age and condition of the unit, as well as the cost of the repair. In general, if the repair cost is more than half the price of a new unit, it’s more cost-effective to replace the system.

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