The photo above is of a real condenser coil we cleaned. The outer fins looked OK, but dirt and lint were packed deep inside. We also had sky-high head pressure and condensing temperature; those are telltale signs of an impacted condenser.

That situation illustrates that a coil can sometimes look OK at first glance but may still need to be cleaned. A close inspection and high head pressure and condensing temperature can be good indicators of a dirty coil.

Before you begin the cleaning, you will want to identify the following:

Is it a multi-row coil?

If so, you may need to split (separate the rows) to allow for cleaning, as shown in the video below.

Is the coil microchannel?

If it is a microchannel coil, you will need to take extra care not to damage the coil and to use very mild cleaners or water alone when cleaning.

In general, never use higher pressure than needed, as that can damage fins and tubing. Try to force soil out of the coil rather than in, and don't use stiff brushes that can damage the fins.

Using Chemical Cleaners

Choose cleaners carefully to ensure that they meet the manufacturer's requirements and that they won't hurt you or the coil. We use Viper cleaner from Refrigeration Technologies for most condenser coil cleaning jobs. We also have a 3D video demonstrating the use of several Refrigeration Technologies products, which you can watch below.

Here is the step-by-step process to perform a great condenser coil cleaning:

1. Shut off the power and test with a meter.
2. Wear gloves and safety eye protection when dealing with caustic cleaners.
3. Unwire the condensing fan motor carefully.
4. Remove the condensing unit top and set it to the side, making sure not to scratch the top.
5. Clean out debris from the bottom and ensure the unit has proper drainage and drain ports clear in the base.
6. If the unit has a hail guard, remove it from the outside. 
7. Protect any controls and electrical components. 
8. Pre-rinse the coil from the inside out.
9. Foam the coil with a foam gun using the proper dilution. Build foam from bottom to top on both sides.
10. Allow the foam to dwell for 5-10 minutes.
11. Rinse straight through the fins and between the tubes from the inside out, working from top to bottom. 
12. Rinse out the base.
13. Reassemble carefully, ensuring that no wires are rubbing or being pinched.
14. Allow the coil to dry fully as it runs before performing final tests. 

The end result should be lower compressor amps and head pressure and better overall system performance. Here is a video of us cleaning a coil from start to finish:

Cleaning the coils is also a critical part of PMs. I have a tech tip explaining our entire residential PM process, which you can read HERE. The light commercial team at Kalos also taught a class about their PMs, which you can watch HERE.

—Bryan