Careful With Cleaners

When I was a green tech, I was really big into showing up all the other techs by doing THE BEST cleaning I possibly could. One of my favorite things to do was to clean the condenser until it was SPOTLESS inside and out. The only issue was that I really liked using that brown coil cleaner—which will remain nameless—in pretty intense concentrations. (It was so dramatic to watch it foam.)

One day, I was washing a Lennox condenser coil and noticed that it was REALLY DIRTY. It didn't look dirty at first, but the more I sprayed it, the more black stuff kept coming off… and coming off… and COMING OFF.

It wasn't dirt.

It was a coil coating, and the thing looked HORRIBLE. Lesson learned.

Cleaning HVAC and refrigeration systems, chillers, and ice machines is obviously not a one-size-fits-all solution, but all too often, we as techs grab whatever we have on the truck and try to make it work. Here are some quick tips:

Read First

I say this in basically every tip, but if you aren't reading, you are ignorant of the industry's risks and best practices. The manufacturer will mention safe uses, concentrations, and hazards right on the bottle. Pay attention to them. This is SUPER important with aluminum micro-channel coils.

Careful What Goes in the Air

When you spray something on an evaporator coil, inside a case, in an air handler, etc., you are putting it in the air people breathe. Are you 100% sure the cleaner you are using is safe for that use? Will it smell like the armpit of Lucifer when you do it? Either way, make sure to take the proper precautions to ensure that you aren't going to harm or irritate the building's occupants. Can anybody say liability claim?

Is it coated?

Coils can be coated with many possible coatings, and they all respond differently to acidic or alkaline cleaners. When in doubt, it is best to use a pH-neutral cleaner. That way, you don't risk eating off that coating (like I did when I was 18).

Nickel-Safe Cleaners

Many ice machines have nickel or tin plating on the evaporator. Use the wrong cleaner, and you can permanently damage the evaporator. When cleaning an ice machine, use specifically designed nickel-safe cleaners to ensure that you don't end up with a mess on your hands.

Be reasonable 

I see many guys use cleaners when a cleaner just isn't required. You don't need to use concentrated chemicals every time you rinse a coil; you don't need to pump a quart of the brown stuff on your truck in the drain pan on every PM. Clean until it's clean, but sometimes a rag, soft bristle brush, or shop vac will do the job better than coating everything in layers of nasty chemicals.

Do a good cleaning. Just pay attention.

For the record – We use Venom packs from Refrigeration Technologies due to their safety and ease of use

If you would like to learn more about coil cleaning best practices, we partnered with SpeedClean and TruTech Tools to put together the following cleaning-related resources:

Coil Cleaning Guide

Mini-Split Maintenance Best Practices




Dale Adams
Dale Adams
1/30/17 at 05:44 PM

A caveat is that the newer coils are denser and sometimes multi row vaccum cleaner…Really …Once surface collects visible gunk the internal sections of coil will be plugged also… Wash properly or let professionals handle…. Train your techs” proper cleaning is essential to correct service” 75% of calls caused by improper maintenance or lack of (40+ yrs in the field daily)
Dirt is thicker than air (Always!!!!!!)

1/30/17 at 07:51 PM

Great advice Bryan I have seen this many times. I use a shop vac 90% of the time on condensers.

Bill hates air conditioning
Bill hates air conditioning
6/18/21 at 04:34 PM

Regarding careful with cleaners. I use car wash and a scrub brush to shine them up. The coil cleaners are for a funky refrigeration unit in the cellar of some greasy spoon restaurant


To continue you need to agree to our terms.

The HVAC School site, podcast and tech tips
made possible by generous support from