Should I use AC leak-sealer, or will it destroy my AC system?

Here are two common questions that I hear frequently from our customers:


1.  Can AC leak-sealer destroy my cars’ AC system by gumming it up?
2.  Is it true that most shops won’t even touch a cars’ AC system if it tests positive for leak sealer for fear of it damaging their equipment?

Suppose a car has a leak on the manifold line and o-ring going to the compressor, and it’s bad. The customer goes to a local auto parts store and purchases a can of R-134A with oil and leak-sealer. The person behind the counter says that there’s nothing to be worried about — the amount of sealer in the can is so minimal. Not only do they recommend it to their customers but use it themselves. Needless to say, most folks can’t pay the $400 to fix the AC, and they are taking the longest car trip of their life soon. They NEED the AC for this trip, and also need this car to be working properly.
So question is: should AC leak-sealers be OKAY to use? Will they gum up the AC system, destroy anything…? And MOST importantly, will shops refuse to service a cars’ AC system once it is used?

My answer would be: I would NOT put the sealer in the system. To repair it properly now will save a lot of money later. Most of those sealers are only temporary, if they work at all, plus, they will eventually clog up the entire A/C system. If that happens, then you will be looking at big bucks to replace the entire system.

If the leak is bad, there’s not can of sealer that will work. Since you were told that there’s minimal amount of sealer in the can, then there’s no way that you can seal the leak.

Some leak sealers only work on SMALL leaks, those that take months to show up. If your system can’t hold a vacuum for 45 minutes, their sealer won’t work.

If it is a hose and O-ring at the compressor, you can take the car to a certified AC technician and have them use a vacuum pump to evacuate the system, change the hose and O-ring yourself and then take it back for a test and charge. My opinion is the cans of refrigerant shouldn’t be sold and putting ANY stop-leak products in ANY automotive fluid system should not ever be the repair procedure, this even goes for Fix-a-Flat. Fix things correctly, or not at all.

As for our shop, if our machine evacuates an AC system that has sealer in it, the sealant will contaminate the machine. Therefore, we will not risk damaging expensive equipment.