The answer to this question is; not many. This is one of those basic tasks that’s so easy no one thinks they need to be taught how to do correctly; and as with all things that appear simple on the surface, there’s a lot more to it than many technicians realize. In fact, it’s one of those things that may be relatively simple, but it can be screwed up ten ways in the blink of an eye.
Speaking of eye’s, before we go any further let’s set some ground rules; Wear safety glasses when performing this work! If you have to use chemicals, protect yourself accordingly with the proper protective gear! Read the directions on the chemicals label and follow them precisely!
Ok, let me hop off my soapbox and get started. The first item I will address is coil cleaning chemicals. Every service truck I look into has at least four plastic jugs of assorted coil cleaning solution. Each has a label that includes information concerning the products use, safety precautions, and some form of slick “snake oil” type advertising that promises bright, shiny coils with minimal effort. No matter, I don’t think anyone ever reads them, instead they pick the cleaner by color; pink for light dirt, blue for heavier dirt, yellow for coils located near Chinese restaurant kitchen exhaust fans. And by the way, everyone knows the green stuff is for evaporator coils and really doesn’t do anything, but for some reason they always keep some on their truck. (Stop laughing, you know every bit of what I just said is true)
Here’s what I think of this rainbow assortment of cleaning solutions; not much. It’s not often you need them. (Ok, I admit it, you do need it for those units near a Chinese restaurant kitchen exhaust. Stop laughing!) What about those fancy chemicals that make the aluminum fins shiny? Who says the fins need to be shiny?! A brush, a vacuum cleaner, and a medium pressure stream of water are all you need to properly clean a coil. In fact, harsh coil cleaners will ruin some types of coils!
Coils that you never want to use a chemical coil cleaner on, unless specifically recommended by the manufacturer, are: E- Coat coils, Heresite coated coils, and Micro channel coils just to name a few. Using the wrong coil cleaner on these coils can destroy the protective coating and possibly the coil itself. The easy way to remember what type of cleaner to use is to not use any cleaner at all if you can help it!
The second item we need to address is how to properly access the coil surface that needs to be cleaned. I know what you’re thinking; how dumb do you have to be to not know how to access the coil? The answer; Not very dumb at all! Many technicians don’t realize that some condenser coils are arranged “sandwich” style, meaning there are multiple single pass coils that are sandwiched together. You usually find this style coil on rooftop units and commercial condensers. On this style coil you need to separate the coil slabs and clean the coil faces in between. In fact, on this type of coil, the outer coil will be clean as a whistle (I’m not sure how clean a whistle is…) and the inner coil slabs will be completely plugged with dirt and pollen. (Anyone who has been in the trade more than a year will know cotton wood is the worst!)
• Use chemical cleaners only when absolutely necessary.
• Make sure chemical can be used without damaging the coil or its coating.
• Access ALL coil surfaces as per the manufactures directions.