A clean air handler can maximize the life span of your equipment, and also prevent allergies and air flow problems. There are many reasons why your air handler could be gather debris, dirt or even mold, so let me cover some of these so everyone can have a better idea of what is going on inside of your air handler.
Dirty Evaporator Coil – This can be prevented by keeping your filters changed regularly, and also using a high grade filter that efficiently catches debris, but doesn’t compromise the airflow of your system.
Some filters, such as those purple ones sold at your Home Depot or Lowes do a wonderful job of keeping the air clean, and the inside of your air handler, but they also put stress on your blower motor and may reduce air flow depending on what type of motor you have. Regular preventative maintenance and cleaning of the evaporator coils can ensure your system stays in top shape.
Dirty Blower Wheel – If your blower wheel is dirty, then more than likely so is the rest of the air handler and insulation. If your evaporator coils are dirty then this can also lead to a dirty blower wheel. Another big cause is air leakage in the air handler.
Many of the newer split residential systems these days are under negative pressure up to the blower wheel compartment, meaning if there are any air leaks at the air handler it is going to be constantly sucking in dust, dirt, debris, mold spores and whatever else might be in the air. If you have electric heat and your blower wheel is dirty then more than likely your heater elements are dirty, and so are all of the connections and wires.
If you live in a warm climate and rarely use your electric heater, and then when you turn it on once or twice a year you may smell something burning. This is an indication that you have some dust built up on these elements.
Poor Air Flow – I don’t know where you are from, but working in Florida for as long as I have, I’ve seen many split air conditioner systems that just have undersized duct work. If your airflow is poor and duct work undersized, there may be more condensation taking place in your air handler than it’s designed for. The blower wheel may be pulling excess condensation off of the evaporator coils pulling it into the rest of the air handler, rusting out electrical components and creating mildew within the system. Especially if you are in a hot humid environment, such as Florida.
If you are in a humid environment, and you air handler is located in a unconditioned garage or badly insulated attic, what do you think is happening when the temperature inside of the air handler is around 60*F and the surrounding temperature outside of the air handler is 100*F+ with high humidity? Same thing with the duct work, yes these are insulated, but more than likely that air handler is going to sweat condensation, and that means mildew is probably growing.
Preventative Maintenance and Air Filtration
If you want to keep the inside of your air handler clean, you want to make sure that your duct work is sized correctly, you have decent air filters, and to have routine preventative maintenance performed on your unit. If you really want clean air in your home and your wallet can afford it PureAir makes some great filtration kits such as the Y2922 Healthy Climate Solutions PCO16-28, which uses a MERV 16 filter along with UV lights, which will ensure you have the cleanest air inside of your home on the block.