How To – Servicing Your Homes Exterior Air Conditioning Condenser Unit

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    One of the most important things about reducing the cost of replacement is to service your home’s mechanical equipment on a regular basis.

    If you have a whole house HVAC Air Conditioning system then you have probably noticed that large thing sitting on the side of your house that has a fan and makes noise.. This is your Air Conditioner Condenser Unit.

    At first glance it may seem daunting to try to service this piece of equipment yourself and if there are real repairs that need to be performed then most likely you will need to contact a professional. However simple maintenance can extend the life of this unit which is half of the equipment needed to provide cool air for your home.

    There are two basic parts of an HVAC whole home Air Conditioning system. The first part is your Condenser Unit… we will get back to that in a second .. your other part is called your evaporator unit. The evaporator unit is simply a Radiator like in your car but instead of holding water it holds compressed Freon. The Evaporator (radiator) is placed over top of your Furnace and the fan inside your furnace that pushes hot air in the winter will push the cold air in the summer. Between your Evaporator which is inside you have lines that take the freon out to the Condenser Unit outside of your home.

    Your HVAC Air Conditioning Condenser Unit

    Your condenser unit has three parts.

    The Compressor – which compresses and runs the freon through your system.

    The Condenser – which is a Radiator to allow hot freon to cool

    And A Fan – The fan forces air through the Condenser Radiator just like riding down the street forces air through your car’s radiator

    Quick Overview Of How Your Air Conditioner Works

    Ok, so we reviewed some of the parts lets quickly look at how the whole system works before we get to servicing the Condenser Unit.

    There are Six parts to the system…. We have two Fans one is in your furnace and one is outside on your condenser. The fans push air through two Radiators. The inside radiator contains cold compressed Freon Liquid.. The outside Radiator contains HOT freon gas.

    The Lines are our fifth part and they connect the two radiators and the compressor.

    When you want cooling in your home the compressor outside your home  squeezes the freon gas into a very cold liquid then sends it through a line  into your house to your evaporator radiator. Your furnace fan blows house air through the evaporator which causes the cold liquid to turn into a gas and it is returned outside to the Condenser Radiator to cool with aid from the fan on your condenser unit.

    Basically its hot outside and cold inside and the cold is after the compressor compresses the liquid. The whole system is sealed and under pressure about twice the pressure found in your car’s tires.

    Servicing Your AC Condenser Unit

    Condenser units are designed to take the elements pretty well but as you will see some rust has started to form on our Fan Motor and Compressor Housing. Also the paint on the fan grill has started to chip off.  The fan grill seems to be galvanized so it probably will not rust right away even without paint but we want to paint it to increase that time period. In addition we will clean the unit for best functioning. Cleaning your unit is something that you may need to do once or twice a year depending on where you live and if you are in areas with a lot of sand or dirt storms then you will need to do it more often.

    Lets get started servicing our unit.

    First you want to turn your Air conditioner off at your thermostat. Most thermostats inside your home will have an off button along with a temperature setting. Once the AC unit is off then you want to turn your circuit breaker for the AC and Furnace to off. Often this circuit is shared but you may have two dedicated circuits one for the Heater one for the AC unit. Turn them both to OFF in your circuit breaker panel.

    Finally outside there is a AC Disconnect box. This box looks like a small circuit breaker but normally it is only a pass through device to complete the circuit. Open the box and remove the Circuit Disconnect Bar to completely cut off electricity to the Condenser Unit.

    A service tech may not go through all of the steps above and may simply remove the disconnect bar. This is not a good idea if you live in a home with many people that could walk over and try to start the unit from inside while you are working outside. Placing a sign on the thermostat that the AC is off and being worked on will let others who may come home through an opposite doorway to not try to run the unit.

    Now that the power is off we can inspect the Unit.

    In our case we take a good look at the rust and new paint that is needed. We will need to remove the fan and grill from the top of the unit by removing mounting bolts.

    Once the bolts are removed the lid can be tilted up from the side opposite of the power line tube. You should not try to remove the fan and grill as there is only enough slack in the wires to allow the grill to be tilted up.

    We place some masking tape on the Unit Housing to protect it from scratches as we chip off lose paint from the grill with a NYLON not metal brush. You must only use plastic or nylon bristle brushes because a steel or brass brush would remove the protective galvanized coating which is very thin.. but keeps it rust proof.

    Once the paint that is chipping is removed from the Grill we start sanding the housing of the fan motor to remove the surface rust. It is important to protect the label on your fan with masking tape before you begin work because it has some settings that are very important if the fan needs to be replaced. The Amps, the RPM, the manufacturer and other specs that will be used to match a generic fan to your unit. Copy this information and place it in your records.

    Finally the top of the Compressor Cover has some surface rust so we will sand that off.

    Once all of the surfaces are clean of chipping paint and rust you want to clean any debris that have built up inside the Unit. If you examine the floor of the unit you will see that there are water weep holes .. you want to remove anything such as leaves, sticks, paint chips that could block those holes and cause water to sit in the unit causing rust. Use a shopvac vacuum cleaner or lots of paper towels.

    Now that the unit is clean we want to prepare the surfaces for new paint. Using a spray cleaner like Automotive Break Cleaner which will evaporate and not leave a residue apply some to a paper towel and wipe the surfaces clean. You only have to slightly moisten the paper towel don’t make it dripping wet.

    Now you can mask off the unit with news paper to protect the parts you do not want to paint.

    In addition to masking the Unit you can see we installed a plastic drop cloth on the wall of the home so that no overspray of the paint will get on it. You do not want to try to get spray paint off after doing a job like this.. take a moment and protect any surface or plant that is near.

    Protect the whole inside of the condenser radiator you do not want paint on your radiator fins.

    Make sure your labels are protected and take a little time to mask around the manufacture’s label on the top of the grill so it looks nice.

    I suggest that you use a high temperature Automotive paint like Engine Paint. It costs a little more but it will provide a much longer life. Standard $2 spray paint won’t last more then a season and you will be doing this all again next year.

    Make sure you apply a thin tack coat of paint then one full coat to the whole surface. Then wait until the paint flashes or drys to touch on a masking tape area and add at least a second coat. Our Grill will get about 4 heavy coats of silver engine enamel.

    Reassembling the Unit

    After the surfaces have dried you want to remove the masking tape and paper before the paint cures fully. This can be done after about an hour. Allowing the unit to stay taped up overnight will mean tape sticking to the surfaces.

    Remove the drop cloth from the home and clean up any debris around the unit that may get sucked in later when you test it.

    Reinstall the bolts that hold the fan to the condenser unit. Do not tighten them too tight or you could damage the sheet metal and then the bolt will always be lose.

    Double check that everything is free and secure then replace the Disconnect Bar in its box to complete the electrical connection.

    You can then go inside and restore the circuit breaker to the on position and then set your air conditioner setting on your thermostat to make the unit come on.

    Return outside while the unit is running and listen for any noises that could indicate a lose bolt on the grill or condenser housing.

    If it is still warm out then keep the unit running for at least a few hours and make sure cool air is being produced.

    Final Note

    As you found out there are very few parts to an Air Conditioning System. Your condenser unit which includes your compressor is the most expensive part but when things break on it you can replace them individually.

    Fans are replaced in two parts. The blades and the Motor.

    Compressors are replaced as a unit and so are condenser radiators.

    The cost of a fan is much less then the cost of a whole unit so servicing and replacing parts individually is in your best interest.  Normally all of the parts do not go bad all at once and One part being bad should not mean damage to any other.

    The most common problem you are likely to run into is a leaky copper supply line that transfers the hot or cold freon gas.  Leaks can be cured by resoldering or using teflon tape on connections. After a leak you will see a black greasy area near the connection.

    Once leaks are fixed or if you need to replace your compressor, Evaporator or Condenser Radiators you will need to refill the system with Freon. ONLY a certified technician can do this and you can expect to pay $50 to $100.. yea it sucks because the freon is no where near that price but the EPA regulates the industry.

    In addition to the work we performed you should also trim back any bushes that are within a few feet of the condenser to allow it to cool easier.

    Servicing your home’s Mechanicals means keeping them in good order and inspecting them for things you can do to extend their life.

    This way Servicing reduces the need for Repairing.

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