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Shoutwire's Guide To Air Conditioning And Heating Maintenance And Repair

Taking care of your heating and cooling unit is a big job, but not too much to handle, especially with the info that we provide here for you.

How HVAC Works

There are 2 separate components to any central AC unit - the condenser and the evaporator. You can usually find the condenser unit on a concrete slab outside the house, and the evaporator coil will be mounted in the main duct junction or the plenum above your furnace.

The majority of central air conditioners are joined to a home's forced-air distribution structure, and because of this, the same motor, blower, and ductwork used for heating are used to disperse cool air from the air conditioning system. When the AC runs, hot air from in the house travels to the furnace by way of the return-air duct, and the hot air is forced across the cooled evaporator coil by the blower, and travels throughout all the vents in the house, thereby cooling it off. In most instances, when the AC is running but the house isn't very cool, you should check for problems in the distribution system.

Call an HVAC Contractor

If you are doing any work on your heating and cooling unit other than routine cleanings, you really need to call in a professional HVAC contractor since both the evaporator and condenser are sealed. Central ACs need to have a checkup and be inspected and adjusted at the beginning of the summer every year. But there are also other things that need to be done every year in addition to this checkup.

Cleaning the Evaporator

Since the evaporator is located in the plenum right above the furnace, it might not be that easy to get to. If you are able to get to it, you should really give it a good cleaning once a year as well. If the plenum has foil wrapped insulation in front of it, you will be able to clean the evaporator, but if it is a sealed metal box, do not even attempt it. If you are able to clean it, here are a few guidelines to help you do the best job:

  • Take off the foil wrapped insulation, which will probably be taped in place. Take care with the tape because you will use it to seal it back up.
  • You will find an access plate behind the insulation, and if you remove the screws, you can lift off the plate.
  • You can use a stiff brush to clean the underside of the evaporator unit, and if you aren't able to reach the whole area, the unit can be slid out a bit for better access. Be careful not to bend the pipes while you are sliding the unit out. A large mirror can help you see what you are doing.
  • Below the evaporator is a tray that carries condensation away from the evaporator, and it also needs to be cleaned. You can pour a tablespoon of bleach into the weep hole in the tray to prevent fungus from growing. In areas with a lot of humidity, you should check the tray and drain it every other day. Sometimes if there is quite a bit of moisture in the pan, it is because the weep hole from the pan to drain line is clogged up. You can use a piece of wire to open the hole.
  • Once you have finished the cleaning, put the unit back where it was, reinstall the plate and secure the tape back like it was.
  • Turn your AC back on, check for any air leaks. If leaks are found, seal them with duct tape.

Maintaining the Condenser

With most AC units, the condenser unit is situated outside the house and will tend to gather dirt and debris from trees, grass clippings, and airborne dust. There is a fan that moves air across the condenser coil, and the coil must be cleaned on the intake side. It is very important that you check to make sure which way the air is moving across the coils before you shut the power off. Here are the steps you need to take to clean your condenser:

  • Trim the grass, weeds, and vines that may have grown around your condenser unit, since it is possible that they may be restricting airflow.
  • You can find commercial coil cleaner at any refrigerator or home goods store, and the instructions are printed right on the package. You will need to flush the coil clean without a hose and then let it dry.
  • Use a soft brush (like a toothbrush) to remove the built up debris, but you may have to take off the protective grill in order to be able to reach the fins. Remember that they are made from light-gauge aluminum and are easy to damage, so clean them very carefully. Do not use a garden hose as the pressure can cause serious damage. Straighten out the fins with a fin comb if they are bent, but again, be careful not to damage them any further.
  • Make sure that the concrete pad that the condenser sits on is level by using a carpenters' level on the front to back and side to sides on top of the unit. You can lift the pad up with a pry bar or piece of 2X4 if it has settled, and then shove some rocks or gravel underneath the concrete to level it off.

In the fall and winter months, you need to take care to protect the outside condenser unit from things like leaf blockage and ice damage. You can do this easily by covering it with a condenser cover that is the same shape as your unit, or you can even use something like a tarp and secure it with a bungee cord.


If you need to test or replace your thermostat, you can find it right behind the control panel. First you will need to take the grill and the control panel off the unit, and look for the sensing bulb that is attached to it. It usually extends from the thermostat into the evaporator coil area, and its job is to sense the temperature.

Remove the thermostat carefully because you have to make sure to return the bulb back to the exact same spot it was in. One tip would be to tag the location of the bulb before removing the thermostat, so that replacing it is no trouble. You will want to use a Volt/Ohm Meter to check the thermostat and set it to RX1 scale. Attach the probes of the tester to the terminals and switch the temperature control dial to the coldest setting. If you get a reading of zero, that means the thermostat is in working order, but if the reading is higher than zero, you will need to replace it with a new one of the same type. Make sure to connect the new thermostat the exact same way the old was hooked up if it was attached to the control panel with metal tabs, screws, or clips.

Another tip - If there are more than 2 lead wires connected to your thermostat other than the sensing bulb wire, you need to call a professional to take a look. Do not try to tackle this yourself.

Regular HVAC Maintenance

Don't wait until there is a problem before doing any maintenance on your heating and cooling unit. If you take the time to do regular maintenance and cleaning on your unit, you can save quite a bit of time and money in the long run, not to mention time spent in the heat when you would rather be sitting in the cool air.

Change out your air filter once a month, and buy a good quality filter. You can buy many types of air filters at home goods stores, just make sure to buy the right size for your unit. You can also purchase a cap from any hardware store that goes on the end of your AV drain. Once you cap it, locate the end of the drain on the outside of your home and use a shop-vac to suck all the dirt and debris out. After vacuuming, make sure that you go back and remove the cap.

You should also get an AC tech to clear the drain with a high pressure vacuum every year at the start of the summer so take care of any backup that could result in mold growth in your AC and water damage to your ceilings and walls. On average, you can expect to spend about $459 on AC repair and maintenance a year. The average homeowner spends between $370 and $548.

If you are planning to give the AC coils a good cleaning, make sure you disconnect the unit first and wet the area you are going to clean thoroughly. Use safety gloves and glasses and spray the coils with commercial AC cleaner. After it sets in for a while, rinse it down well afterwards.

Installing a Window AC Unit

In some instances, you may find that a window AC unit works better than one of the larger units. Installing a window unit is pretty easy, and compared to central AC units, it is pretty cheap.

If you have never installed a window unit before, note that you must measure the window to make sure that the unit will fit in the window properly. Choose the window carefully, and remember that a north-facing window will give you a better airflow. You will also want to make sure that the area you plan to install the unit in is close to a grounded three-pronged outlet. If you need an extension cord, you will need to purchase one that is specifically designed for air conditioners, otherwise it will probably overload your circuit.

When choosing what size unit you will purchase, remember that you will want a unit with a high BTU, or at least one high enough to properly cool your space. And if the unit is not as wide as the window is, use side panels that extend on both sides of the AC to cover up the gaps.

Ask Before You Install a Window AC Unit

If you are a renter, make sure that you give your lease a look before you install a window unit. Many management companies either do not allow them, or require that they are installed by professionals. If the latter is the case, you can purchase your AC from a place that provides free installation, and save yourself some time and money.

To prevent the likelihood of an accident, make sure you have a friend or family member with you during installation since window units can be really heavy. You do not want to run the risk of the unit falling out of the window, or worse, on you. Also remember that once the unit is installed, opening that window is no longer an option.

How to Troubleshoot a Window Air Conditioning Unit

Window AC units work much the same way that central AC units do, only they are on a much smaller scale and are generally more expensive to operate. If you purchase one with high enough BTUs, it may not only cool of the room you put it in, but adjoining rooms as well.

In between the coils in the AC you will find two fans, a compressor, thermostat controls, and a motor. Usually if you find yourself with a unit that is working improperly, the cause is too much dirt inside. It can make the AC run less efficiently, block the fan from operating correctly, clog filters, and clog up drain ports.

With most window units, the compressor, coils, and motor are sealed components, so if you need to repair anything, it is best to go ahead and call a professional HVAC contractor. Of course if you are able to get to the parts that need cleaning you can do regular maintenance and repairs yourself if you know how, but if you need a ac repairman, the cheapest way to go is to remove the unit from your home and take in into a local shop to be repaired.