Nu-Calgon 4050-11 EasySeal Direct Inject-UV Dye Refrigerant Leak Sealant, One Size Treats Systems 2 to 7.5 Tons

I’ve used this product over a dozen times as a certified HVAC technician. Only once has it not worked and it took several months to lose the refrigerant again. If you’re trying to stop a MINOR leak and you have lost half your refrigerant (example 50 psi or less for R22 and 70 psi or less for R410A), don’t expect this product to work. Use common sense!

Great, ease to add into the system and worked really quick to seal small hole in the coil. Excellent value and saved time and money of a coil replacement.

I was hoping this product would've found the leak and seal it. The leak must've been too large for this product. It started clumping around the leak, so I had high hope. I was able to easily find it, in the inside unit evaporator coil, on a U bend. Had a buddy come over and brazed the leak. Good as new.

I was very skeptical using this product and I was also concerned about stopping up the free on system and totally ruining it. I didn't have a large leak I don't have a clue where it was it was very slow. But honestly I'm very happy I used this it worked very well it stopped my free on loss totally since I put this product in the system I have not had to add any more freon to the system and it works very well

We are in South Florida and I do our HVAC work since I did it for a living before retiring. We HAD a pinhole leak in the evap on our Lennox 2.5T. I was adding .5 lbs of 410a monthly. I keep a spare Lennox evap brand new in the garage but I was in cancer treatment and did not want to replace it. It's still there. I added one shot of Easy Seal. Now February 2026. In four months it'll be three years. No leaks! My leak detector does not even pick up the leak anymore. This product is not just a "seal". It plates over the leak. Nu-Calgon makes other HVAC products as well, for cleaning, etc... I tend to stick to their excellent products. Under the labeled conditions it does what it says! Great product! Little pinhole leak in the evap. I used this in June 2023. It is now February 2025. We live near Tampa Bay in Balm Florida. We have some summer days of 105° with a Reelfeel of 125°. I was losing .5 lbs per month up until June 2023. Since adding this product nineteenonths ago, no leaks. 2010 Rheem.14SEER 3.5T.

Snake oil so did not work. I was very hopeful but totally disappointed, it did bit stop any leaks. I wasted the price for this item and the additional refrigerant cost. I did not get any refund.

Update: 9 months later and still no leak I have waited 2 months after using this product to write this review. I have a 22 year old R22 unit that was losing about a half a pound of refrigerant a month. So a slow to moderate leak. This product was my last attempt to save this system. I have HVAC experience and found the product easy to use. After 2 months I have not had to add refrigerant and leak seems to be sealed. This system is on a rental unit and if I can get a few more years out of it I will be happy. I recommend this product as a last ditch effort to extend the life of a failing system.

Had a small leak, lost 8lbs of freon over 7 months. Used this and it sealed the leak for about a month and then the leak opened up even worse. Another application and had identical results, held for a month. On the final application the fluid failed to hold at all. The issue was the leak was undetectable on the first and second application. Only on the third use I was able to locate a pinhole leak, so ordered freon and had to wait for it to arrive and needed a temporary fix. Obviously, I understand this product is not a solution for all leaks, but based on the size of the leak detected I was disappointed that this could not handle it on its own better. After cutting the copper line and replacing the section affected the unit is back to 100%. So that was the only leak. Moral of the story is be diligent when inspecting for the leak with a UV light and don't expect this to hold up over long periods of time. With each application it becomes significantly less effective, at least in my experience using this. On other units, if the leak is small enough (microscopic) this will be a fine solution to hold over for a year maybe even longer. This is a good product, just dont expect it to work miracles.