Air Conditioning Problems. Home Heating Problems. HVAC Questions. MY HVAC MD is here to help.

Have you ever wandered over to your Air Conditioning vents and put your hand out and thought, “The AC must be working, there’s cold air coming out.”   Actually, just because cold air is coming out of the registers does not mean the system is performing properly and efficiently.  Air Conditioning actually works on the principles of removing heat and moisture from your home.  The term Air Conditioning is defined as the simultaneous control of temperature, humidity and motion affecting both the physical and chemical conditions of the atmosphere within a structure.  Other factors that can affect conditioning are distribution, dust, bacteria, odors and toxic gases.  This means that an efficient performing system needs the air in a room to be cooled, dehumidified, cleaned (filtered), and circulated.  The actual cooling of the air is just a segment of Air Conditioning.  Let’s breakdown each major segment on the principles of Air Conditioning.
Cooling: The heat in the air is cooled by passing through an evaporator.  I am going to keep this simple, so I will not explain the meaning of Heat Transfer or Latent Heat.  The evaporator is the refrigerant-containing coil inside the indoor unit in your home.  Heat is removed as the air passes through the coil.  This is an important statement because the air has to pass through the coil before the heat is removed. Proper refrigerant pressures are another major factor for the appropriate removal of heat in the air.
Dehumidification: This is defined as the process of removing water vapor (moisture) from the atmosphere.  As it applies to the principles of Air Conditioning, the air is dehumidified by passing through the evaporator.  Again, proper refrigerant pressures aid in the appropriate dehumidification of the air.
Cleaned (Filtered): Most of us know that the air filter is what cleans the air as it circulates through the system.  Did you know that the evaporator also assists in the removal of impurities from the air?  The best air filter can not remove 100% of the impurities that circulate through the system.  As we learned, air that passes through the evaporator is dehumidified.  This process creates condensation which can trap some of those impurities.  This is a good factor, right?  Actually, this can be bad.  A very serious issue when it comes to most systems performing efficiently.  Debris that is trapped on the evaporator obstructs the air from passing through the coil.  This reduces proper heat removal and dehumidification.  It also produces improper airflow and lowers refrigerant pressures, causing your system to use more energy to generate suitable temperatures.  See the domino effect?  Did you know that the dirtier the air filter the more debris is forced onto the evaporator?
Circulation: The only way the air can pass through the system is proper circulation.  This includes clean air filters, evaporator, blower wheel and ductwork. Blower wheel and ductwork?  Yes, these also have to be clean for efficient conditioning.  The blower wheel is a finned wheel that is powered by the blower motor.  Both need to be clean of dirt and debris to perform effectively.  Have you ever pulled off an air vent to see the debris inside the ductwork?  Well, this is only about 1% of the actual debris, dust and bacteria trapped in your ductwork.  The years of accumulated dirt and impurities that build up inside ductwork over the years can be overwhelming.  If your system is over 5 years old and operates with a standard air filter, you probably need your ductwork cleaned.

Let’s summarize what needs to be checked for efficient and healthy home Air Conditioning.

1. Clean Air Filters
2. Clean Evaporator Coil
3. Clean Blower Motor and Blower Wheel
4. Clean Ductwork
5. Proper Refrigerant Pressures

Here is a brief checklist to create and maintain proper Air Conditioning.

1. Check and clean your air filter on a monthly schedule during the season. If it is a standard filter you may want to get prices on other types that trap more dirt and impurities in the air.
2. Have a Professional HVAC Contractor check and/or clean your evaporator coil, blower wheel and blower motor. They should also check your refrigerant pressures and Condensing (Outdoor) unit.
3. Have a Professional Contractor that performs Duct Cleaning and Indoor Air Quality (IAQ) check your system and give you advice on what will fit your needs and pocketbook.

Mr. Kannon is a contributing writer for MY HVAC MD.com and its affiliate Web sites. Due to development constraints, please no technical questions.  He can be reached at kausekannon@myhvacmd.com.