Does AC Stop Leak Sealer Work? (& Is it Bad?)

Repairing the AC system can be very costly. What about AC leak sealers? Do they work and can they save me some money? Let's find out!

Does Ac Stop Leak Sealer Work

If you like to work on your car yourself and you know a little bit about cars, you must have come across leak sealants when buying accessories for your car.

Most people who haven’t used a leak sealant before will wonder if it really works because the advertising for these sealants implies that these things are magic and will immediately seal AC leaks and other types of leaks in your car.

You get a low-cost product that will fix your car’s problems that would cost you several hundreds of dollars if you decided to have it checked and repaired by a mechanic.

This raises the question of the credibility and authenticity of these AC leak seals. Is it too good to be true, and could you do more harm than good by using these AC leak seals in your car?

Let’s find out!

What is an AC leak sealer?

An AC leak sealer is a product that works by reacting to the temperature when the refrigerant is flowing out from a pinhole in the AC pipe. When reacting to the leak location’s temperature, it will become a hard sealer instead of a liquid, and therefore it will stop the leak.

Even if you may think so, AC leak sealers are not new on the market. In fact, these products have been widely used in the natural gas industry for many years. These compounds have long been used to seal small leaks in gas pipelines to save time and money for manual repair.

Chemical-based sealers consist of a thick liquid substance that reacts with temperature and water to form a sealant that looks like epoxy resin. There are also particle-based sealants that work differently from chemical-based sealants.

Ac Leak Sealer

Does home AC leak sealers work?

Most AC stop leak sealers work well to stop small pinhole leaks in the AC pipes, but it’s not recommended by us. It is not proven that they can stop leaks around O-rings or shaft seals, which is much more common than pinhole leaks in AC systems.

There are a lot of different opinions when it comes to AC leak sealing. Here are the advantages and disadvantages of using an AC leak sealant, so you can ask yourself if it is worth it.

In my opinion, it is much better, and also probably cheaper in the long run, to repair a leak properly.


  • They can repair minor AC leaks, like pinhole leaks.
  • It can save you a lot of money instead of replacing expensive parts in the coolant system
  • Can prevent further leaks
  • Cheap to purchase


  • They can clog the expansion valve, the AC evaporator/condenser as well as other parts. This can cause way more extra repair costs.
  • They can disturb the flow and pressure of the AC system. This can cause the efficiency to reduce by up to 10%.
  • Large leaks cannot be repaired.
  • It is not proven that they can seal around O-rings and shaft seals, which are the most common leak places.
  • It is often more of a temporary solution than a permanent one because of the high pressure within the AC system.
  • If you visit a workshop and notice that a leak sealant is present in the AC system, the system must be flushed before. The additional costs of this are at least $100 or even more. If they do not know about the leak, it can damage their AC machine, costing over 5k dollars.

RELATED: How Much Does an AC Recharge Cost?

Is AC Stop Leak Sealers bad for the AC system?

Car High Low Pressure Connector

Yes, AC stop leak sealers are bad for your AC system. It can clog important parts like the expansion valve, evaporator, or condenser. It will also reduce the efficiency of your AC by up to 10%.

You must understand that AC stops leak sealers are reacting to water, and when it does that, it will become hard. This is why it seals small pinholes by reacting to the condensation caused by the temperature around the pinhole.

When you have an AC leak, not only AC refrigerant will go out of the system – water or condensation will also go in. As we told you before, the AC leak sealer is reacting to water – so what happens when you pour the AC leak sealer into a system with water?

Exactly! It will cause it to harden inside the AC system, and this can happen at places like the expansion valve or the condenser, which can cause the AC system to stop functioning at all. It will often also result in an expensive repair cost.

What is the best AC leak sealer?

If you, against all odds, still want to use an AC leak sealer in your car, the best AC leak sealer I would recommend is the Red Angel A/C leak sealer from Amazon. Here it is:

Red Angel A/C Stop Leak & Conditioner
960 Reviews
Red Angel A/C Stop Leak & Conditioner
  • Guaranteed Permanent Seal
  • Will Not Clog or Damage the A/C System...
  • Compatible with R-134a

Remember that even if it says that it does not clog the AC system, it still can happen, and you need to be prepared for that. Also, remember that it can end up with more expensive repair costs if you use it, so I do definitely recommend repairing the leak properly instead.

The different types of AC leak sealers

There are actually two different types of AC leak sealers that you can use, and both of them have their own pros and cons. Here are the two most common types of AC leak sealers.

1. Powder/grain-based sealers

The first, the powder or grain type, is a sealant that contains tiny particles inside the compound. This particle-based sealant works by plugging the leak or cavity with its tiny particles and forming a fine sealant. The tiny particles sit together inside your refrigerant line.

Using this type of AC leak sealer, there is a big risk that they will clog your AC system, so we do not recommend them. In addition, these types of AC leak seals are getting older and older, so you will probably find chemical-based AC leak sealants in most cases.

2. Chemical-based sealers

The second type of AC leak sealers, containing a chemical compound, is now more common on the market. They exist under different names and brands, but their purpose is the same. Their purpose is to seal the leak so that the refrigerant does not escape.

These chemical-based seals seem to be safer than the first type because these seals do not really block the leak but form a tight layer over it to prevent the gas from escaping.

These chemical-based compounds can be supplied in a single bottle, as we have already discussed, or in two bottles, with the sealant and conditioner in separate containers.