This project is continued from Part 1.
AC Evaporator Coil Inspection
This is a closeup of my evaporator coils before cleaning. The coils look very clean already because I service my system regularly. Of some concern is the rust on the ends of the frame. The unit is about 9 years old and rust is common in these areas. The greenish/whitish discoloration on the copper refrigerant lines is from dissolved copper deposits that have dried. The plastic drain pan looks in good condition with no cracking or leaks. Overall, not too bad for a 9 year old evaporator coil. I should expect to replace the coil and/or air handler in a season or two as it approaches the end of its expected life.
For comparison, click here for photos of some really dirty evaporator coils. If yours looks really bad, you should consider hiring a professional HVAC technician because you may need to:
- Remove the gas furnace section to get access to the inside of the A-frame coils from underneath for a thorough cleaning inside and out.
- Remove the coils for cleaning and/or replacement.
Air Conditioner Evaporator Coil Cleaner
I purchased a can of Frost King Air Conditioning foaming / no-rinse coil cleaner from Home Depot, which did a good job. You might also look at professional products such as Nu-Calgon coil cleaners and sprayers that are widely available on eBay.com.
Cleaning the Evaporator Coils
The foaming coil cleaner is sprayed directly on the coils, coating the surfaces evenly and thoroughly. It’s best to do this on a warm day when the A/C will be running to help rinse the coils with condensate water.
The spray foams nicely on the coils.
The no-rinse foam cleaner breaks down and liquifies quickly for a good rinsing action.
In minutes the foam is rinsing itself off and draining away. Always check the PVC drain line is free of algae and unclogged. I poured a quart of 50/50 solution of household bleach and water in the drain pan to keep the line clear. You can also buy time-release algae tablets to drop in the drain pan.
The access panel is reattached with the sheet metal screws. The top and bottom seams are sealed with metal foil tape.
Take care not to tape over the manufacturer’s label on the access panel.
The attic air handler is now ready for another hot summer of cooling. The last task is to turn on the thermostat.
HVAC Air Handler Basics
Now you’re familiar with the basic components of the attic air handler and the importance of changing the air filter and performing routine system maintenance. If your AC system needs professional servicing, you’ll know what the HVAC technician is talking about. Annual Service Contracts are available from HVAC companies and usually cost less than the sum of ad-hoc maintenance calls.
Heavy Duty Coil Cleaning
Please see Part 3 which explains how to inspect and perform a heavy duty cleaning of the interior side of the A-Frame evaporator coils.
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