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AC evaporator coil leak – TLDR

  1. Figure out your refrigerant type – R22 or R410a
  2. Determine how old your HVAC system is or – more specifically – how much life it has left.
  3. Determine how long you will remain in the home. Are you there to retire or are you selling in a month?
  4. 10 years or older and R22 – Consider replacing the whole AC system.15 years or older and R410a – Consider replacing the entire AC system.

The Details

On the residential side, the problem of a Freon or refrigerant leak in an AC evaporator coil is one that I hate the most because it is expensive to fix correctly.

Before I get into the solution, let’s cover some basics.

Your AC system is a heat pump because, well, it pumps heat from inside your home to the outside during the summer months. To do that, you have an indoor coil (the evaporator coil), and an outdoor coil (condensing coil), with a compressor in between. Up until recently, HVAC coils were copper tubing with aluminum fins. This copper and aluminum design worked well enough, so it became the predominant design for decades. The main reason being was that copper is an easy metal to work with when it comes to mass production.

However, copper and aluminum will corrode over time and water being present (humidity) accelerates this process. Furthermore, when you have a humid environment as we have here in The Woodlands Tx, it makes this corrosion issue worse. There are also cases in this area where drywall suppliers improperly imported Chinese drywall during building material shortages after hurricanes. The problem here is that this Chinese drywall releases a sulfur gas that accelerates the corrosion process immensely.

The bottom line is this – Both the indoor and the outdoor coils corrode, rust, or degrade over time, due to the copper and the aluminum reacting with each other. Furthermore, copper and aluminum have been used for so long due to the combination working so well in mass production.

Okay, so we have copper and aluminum that will corrode, but 8 to 20 years is doable, as long as we do not have Chinese drywall.

AC Evaporator Coil Leak Symptoms

When you have an ac evaporator coil leak, you, the homeowner, will first notice the following symptoms:

  1. Coil and/or outdoor unit icing up
  2. AC system runs ALL THE TIME
  3. House is warm or won’t cool down as it used to
  4. AC system does not work at all – No cooling
  5. Your house is humid or damp, and you may have even contemplated buying a dehumidifier.

Now, if it has been established that there is a leak, we need to determine the refrigerant type before we can go any further with the decision making process.


  • R-22 is an older refrigerant that has been in use for decades.
  • It is a CFC or a chlorofluorocarbon, which puts a hole in the ozone layer. These were used in things like hairspray up until the early 90s when they were banned.
  • It works with compressors that use a mineral oil (non-synthetic).
  • Coils designed for R22 work with its lower operating pressures.
  • Because it is a CFC, the US Government is restricting the manufacturing quantity each year, which, in turn, raises prices. As of October 10, 2017, we only charge $45 per pound, so it isn’t that expensive, but I have seen companies billing as much as $150 per pound which is, in my opinion, downright criminal.


  • Newer
  • Required in all new HVAC systems from 2007 onward.
  • R-410a does not hurt the ozone layer (not a CFC).
  • Coils designed for it are designed to handle much higher pressures.
  • R-410a requires the use of a synthetic oil – not compatible with mineral oil.

Determining Your Refrigerant Type

How do you tell which one do you have? Well… There isn’t a sure fire way to go about this, so you just need to do a little research on your outdoor unit.

  1. R410a systems often have pink (or faded white) labels that say R410a somewhere on the outside.
  2. If you look at the outdoor units data placard, where the model and serial number is displayed, the refrigerant type should be listed there as well. It will say something along the lines of Factory Charge R-22 – 74 ozs.
  3. If that fails, you can then start looking up the model number online that is listed on this data placard.
  4. If all of the above fails, you might need a professional to come out to take a look.

If your coil just happens to be more towards the 8-year end of the spectrum and you are using the older R22 refrigerant, you are left with a horrible situation. “Well, what do we do then??

Can You Just Repair The Coil?

1) Well, every time I am asked if we can just repair the leak. Well, yes, we can BUT:

  • It ends up being almost as expensive as replacing the coil.
  • It ends up being a game of whack a mole where more holes can form an hour later (remember it is an old brittle coil that is leaking due to corrosion).
  • Unless it is an apparent leak that isn’t the result of corrosion, we will not repair it.

“Okay, Anthony, so repair is out of the question. What options are left?

Coil Replacement On An R-22 System

2) We can replace the coil and keep you on R22 with your existing outdoor unit. The typical coil replacement costs here are $1300 to $2000. However, the problem with this solution is that if your outdoor unit breaks two years down the road, we must start over with a new R410a coil and new R410a outdoor unit. And, yes, you can hook up that two-year-old attic coil that has been used with R22, to a new R410a outdoor unit. However, you are asking for trouble and this is a corner that we refuse to cut.

** If you plan on selling this home in less than a year, this may be the better option for you financially.

AC System Replacement

3) A final option would be to replace both the coil and the outdoor unit, with new components that run on R410a. We can even pump down your existing, working, R22 outdoor unit, so that you can easily sell it on Craigslist to someone in the opposite situation (R22 system with a good attic coil and a bad outdoor unit) AND (you are on your own here).

In my humble opinion, although it costs more in the immediate term, going this route is the best way to go but it will set you back $2800 to $3500, in most cases. But, with us at 33 Solutions LLC, you will have a 10-year parts and labor warranty (lower maintenance costs) and lower electric bills.

a) New R410a refrigerant equals lower maintenance costs going forward.

b) A 10-year factory warranty due to a new matched set – both the attic coil and outdoor unit.

c) All of our new coils are now Trane solid aluminum evaporator coils, which have shown to last 3 to 4 times longer than the traditional copper aluminum coils, in both the field and the laboratory (more on these solid aluminum coils in another post).

d) More energy efficient – Lower electric bill.

** If you plan on staying in the home for any length of time, this is the way to go.

Coil Replacement On An R-410a System

Now, if you happen to have an HVAC system that works on the newer R410a refrigerant and it is in excellent overall working condition, then the answer is simple – We just replace the evaporator coil! That is, unless your R-410a AC system is approaching 15 years of age, you may want to consider replacing the outdoor AC unit as well.

I know, it sucks, because it can be expensive to do things correctly. However, we are not salesmen, and we try our best to be straightforward and honest. Other companies may tell you whatever you want to hear and also promise you the stars if you go their cheaper route. However, I see upset homeowners all the time, complaining about how they were previously wronged and the person responsible is no longer in business.

If you have any questions, please feel free to contact me – Anthony – at 33 Solutions LLC!