Dirty Evaporator Coils Reduce Available Cooling.

As evaporator coils cool indoor air, they dehumidify or remove moisture. Any dirt, dust, nicotine, pollen, and many other allergens and pollutants, that are in the air will combine with the moisture and eventually foul the coil. Once this occurs, two problems arise: air flow is restricted or reduced and heat transfer is restricted or reduced. All this cuts cooling capacity and, if the coil becomes extremely dirty, the compressor could be damaged.

CLEAN EVAPORATOR COIL

DIRTY EVAPORATOR COIL

Dirty Evaporator Coils Reduce Quality of Air Inside the Building.

Going back to the discussion on moisture and combining with dirt, dust, pollen, etc., this also becomes an excellent breeding ground for biological growths like bacteria, mold and mildew. These are the primary sources of indoor air quality problems and odors. As the air continues to flow across the coils and circulate throughout the building, its quality is compromised

Contactors

A contactor is like a large relay. Relays are generally used for switching light loads like control circuitry and relatively small motors. Contactors are used for bringing larger loads online like compressors and large motors. Contactors can have 1,2,3 or 4 sets of contacts. Contactors have normally open contacts but can also have auxiliary contacts which can be normally open or normally closed.

clean/new contactor

Although the contacts snap shut quickly, arcing occurs between the contacts as they approach the closed position. This arcing eventually wears out the contacts. It is wise to inspect the condition of contacts reasonably frequently and replace the contactor before they become so pitted and burnt and carboned up that the compressor (or whatever load) is placed in danger. If contacts stick shut, a compressor can continue operating regardless of any operating or safety controls that may open. It can continue operating in the absence of evaporator and/or condenser fan motors which can cause compressor failure in short order.

Dirty Condenser Coils.

The hot refrigerant after being compressed by your compressor travels through the condenser coils.

The airflow blowing accross that coil removes the heat in the refrigerant. If the coil is dirty, you are not allowing proper heat removal/transfer accross the coil, and you are reducing the efficiency of the system and reducing your cooling capacity.

In addition, your compressor uses the air flowing through to help cool it down. If the coil is dirty, you are reducing the amount of air flowing accross the compressor. The compressor will run harder, hotter and you could very well damage the compressor.