Rust and corrosion are common problems faced by nearly every air-conditioning system in use today. This dynamic duo of destruction can put a slow yet grueling end to your home comfort by eating away at a variety of important metal components, including the copper tubing used for your air conditioner's evaporator coil.
So the next time you're wondering why your A/C isn't blowing as cold as it used to (and you've ruled out all the other potential factors), you might want to take a very close look at your evaporator coil.
Each day, the evaporator coil is exposed to a wide variety of chemicals in the air. Among these are certain volatile organic compounds (VOC) commonly found in number of household products, from adhesives and latex paints to tobacco smoke and cleaning solvents. When residual traces of these chemicals are exposed to the evaporator coil's moisture-laden environment, they react to form acetic and formic acids that eat away at the copper metal.
A close inspection of your evaporator coil tells the tale: coils suffering from formicary corrosion reveal a cluster of near-microscopic pin holes that resemble ants' nests. In some cases, it's also accompanied by bluish-gray or black deposits along the affected surface. Needless to say, these microscopic holes can penetrate through the surface of the coil, causing leaks to develop throughout the affected line.
Once formicary corrosion gains a foothold on your air conditioner's evaporator coils, you're left with three options:
1)You can try fixing the problem by adding refrigerant leak sealant, which attempts to fill in the microscopic leaks throughout the coils, to your A/C system. Keep in mind that this is, at best, a temporary solution for restoring your A/C to working condition until you're able to fix the problem for good.
2)You can replace your evaporator coil with one that is less susceptible to formicary corrosion. For instance, evaporator coils made from aluminum feature a thin oxide layer that resists most forms of corrosion.
3)You can replace your air conditioning system altogether with a newer model like Xcel Energy Home Smart. This may be a good idea if you see signs of corrosion or rust in other areas of the unit, but it's also the most expensive option on the table since both indoor and outdoor units housing the evaporator and condenser coils must be replaced as a matching system.
As always, prevention is the best medicine. For instance, reducing your use of household products containing VOCs can help reduce the chance of formicary corrosion forming. You can also thwart formicary corrosion by applying a protective coating on the evaporator coil, which helps repel the chemicals responsible for corrosion.