Cleaning the Evaporator Coils
Again, we recommend a professional do this work. A professional will have all the proper tools to complete
the job quickly and efficiently.
Make sure you follow the safety procedures noted above about cutting power to the unit
before attempting to clean the coils. Once you have turned the power supply off from the
air handler, open the panel where the suction and liquid lines run into the unit. Be very
careful not to bend or crimp these lines or any lines in the air handlers. Another thing to
avoid is the fins on the coils. Do not bend them. That would defeat the purpose of cleaning
the coils because it will reduce the amount of air flowing across the coils. Check the drain
line before you begin this procedure. See condensate drain section below for more information
on this subject. Soak the coil with a soap and water solution. Professionals use an industrial strength coil cleaner which
may be available at some hardware stores. Let this solution soak for a few minutes and then
take a rag and wipe as much dust off the surface of the coils as possible. Repeat these steps
until the coils look clean. Take a flash light and look between the fins. They should appear
to be clean. If not, soak the coils again and use a brush with light bristles to brush the
coils. Remove as much dust, dirt, and debris as possible. Remember there are two sides
to the coil and make sure both sides are clean. The side that will most likely be dirty
will be the side where the return air flow comes from. If your coils are clean and the rest
of your components are operating normally you should have a nice cool summer inside your home
no matter what the weather is outside.
Checking the Blower Motor
The blower is comprised of different components in most units. It has an electric motor,
a squirrel cage blower wheel, and a cage typically referred to as a squirrel cage. Some units
have belt driven motors and most have capacitors for the electric motor. The only required
maintenace on the blower is oiling the motor if it has oil ports or checking the belt if you
have a belt driven motor. Not all motors have oil ports. These motors use sealed bearings and
never require oil. The motors that do have oil ports usually have little plastic dust caps that
can be removed so that oil can be applied. They can be removed so that the bearings can be oiled. Not all motors have caps and not
all caps are yellow.
Checking the condensate lines are especially important if your air handler is
located in the attic. Since the evaporator coil operates at a temperature less than dew
point, it will condense the moisture from the air. This coil is designed to allow the moisture
to drip into a pan. Most pans have a 3/4" PVC line attached to them that allows the moisture
to drain to the outside of the house. The PVC line often becomes clogged with algae and muck
and needs to be blown or flushed out from time to time. If your air handler is in an attic it
should have a secondary pan to catch the water in case the primary pan or line gets clogged. We
recommend that all secondary pans have float switches installed. This switch will cut the unit
off if the secondary pan starts to over fill. This will save you from buying a ceiling. Float
switches can be installed by your local HVAC service company.
Check to make sure that the condensate line is not plugged by pooring water in the pan.
If it drains fast then the line should be okay. If it drains slowly or not at all then the
line is plugged or beginning to plug. Find the end of the line outside and take a hose
and flush the line. You must be careful if you do this procedure. You can flood the pan and
cause water damage. This will clean the line in most cases. If it doesn't you need to call a
professional. They should have all the necessary tools to blow the line properly.
All of these checks can be made by your local heating and air conditioning company. Just call
and ask for a spring tune up or a maintenance agreement. A little preventive maintenance can
save you a lot of money in the future. Take the time to have this maintenance done and save
yourself from the expense and hardship that comes with breakdowns.
In depth information:
By the time it reaches the end of the coils it should have absorbed enough heat to change
it from a liquid to a vapor. What are the reasons why the coil wouldn't absorb enough
heat to change the state of the refrigerant?
- Dirty Filters
- Dirty Coils
- Collapsed Duct
- Too many supply vents closed off
- A bad blower
The bottom line is airflow. There must be the proper amount of airflow across the coils for
your system to operate efficiently. Take this one step further. If you have one of the aforementioned
problems listed above and the refrigerant remains a liquid, what happens? Refrigerant leaving
the evaporator is on a non-stop trip to the compressor. It is important that the refrigerant
has changed from a liquid to a vapor before it reaches the compressor. Liquid doesn't compress
and can cause major problems if it reaches the compressor. It's called liquid slugging and can
cause irreparable damage to the compressor.
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