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Do AC and HVAC Leak Sealers Actually Work?


AC leak sealers are not new to the market. They have been around for the longest time and have been used to seal small leaks in pipelines, especially in the natural gas niche as well as for the automotive market. In the past decades, they found their way into the HVAC industry, bringing about a raging debate that has continued for years: Do Internal AC leaks sealers work, and should they be used for sealing refrigerant leaks?

There are two schools of thought: there are technicians that have used these AC leak sealers for years and can swear by them to be cost-effective and practical for sealing hard-to-find and tiny leaks. On the other hand, some feel that every leak should be repaired conventionally by a technician. They further argue that these AC sealers will harm the AC units by plugging up parts of the valve, compressor/evaporator, and affect a cooling unit's smooth operation.

What Is an AC Leak Sealer?

Before we can jump into the details of whether Internal AC sealers work, let’s start somewhere – what is an AC leak sealer?

As the name suggests, a leak sealer is a blend of chemicals (fluid) used in minor leak restoration. This fluid is inoculated into an HVAC system to help in sealing small leaks that are hard to detect. Once the sealant is injected into a system, it is activated by moisture, in turn solidifying to form a permanent patch.

I know you’re wondering where the moisture comes from in the system, right? Well, if there’s a leak within a cooling unit, there will be a temperature differential at the point of the leak causing condensation and hence the ‘moisture’ to activate the sealant.

Types of AC Leak Sealers

There are two common AC sealers in the market today. Let’s look at each type.

1.    Grain/Powder-Based Sealers

These sealers are getting older and older and being replaced with the second type of sealers. They are not as effective as their counterparts. They are made of powder with some tiny particles inside. These sealants work by plugging the cavity or leak with the tiny particles to form a seal.

Once they are introduced into the system, they sit inside the refrigerant line. They are ideal for unpressurized conditions – however, most AC lines are pressurized, and therefore, these sealants might not be best. There’s also the risk of forming a clog when using these AC leak sealers.

2.    Chemical-Based Sealers

These are the most popular AC sealers among HVAC technicians. Chemical-based sealers are much safer compared to the powder ones – they don’t fill to block the leak; instead, they react with moisture to form a permanent patch.

Once chemical-based sealants are introduced into the refrigerant line, they flow. If there’s a leak in the system, there will be a temperature difference at the leak point and consequently some moisture that will activate the sealant forming a sealing patch. The seal is usually permanent – it’s like a chemical weld inside the refrigerant line.

Advantages of AC Leak Sealers

  • They are ideal for pinhole/minor leaks – they will seal even the hard-to-find leaks
  • Easy to use
  • Cost-effective
  • Safe to use
  • You don’t have to tear apart the entire system to fix a leak
  • You don't have to evacuate and refill the system

Disadvantages of AC Leak Sealers

  • They are not suitable for large leaks
  • Some might clog the condenser/evaporator or parts of the expansion valve (especially the powder-based sealers)
  • Some sealers might alter the flow or the pressure of a system, reducing its efficiency
  • Different leak sealers are needed for different refrigerant systems
  • It might not work for shaft seals and O-rings
  • And most importantly: they don't fix the actual cause of the leak!

So, Do AC Leak Sealers Work?

There’s a difference of opinions when it comes efficiency of even the best leak sealers. Even after looking at the Pros and Cons, it is evident that some AC sealers will work while most others won’t really get the job done, especially for long-term fixes. If you’re going to use these leak sealers, hold on to your expectations, but also keep them minimal. Most technicians are able to fix any leak on any system, but especially with a really old system, fixing the leak might not be worth it, and not all customers have the means to afford to fix a leak or to replace the system.

Before using a leak sealant, find out its advantages and disadvantages. Also, look at the options that you have before establishing whether to go the sealer way. Manufacturers insist that these products are effective, efficient, and safe.

However, the final answer really lies with your best judgment; is this the right solution for your customer? Is this the only way to fix this problem, and will it actually be a long-term solution? There are very few situations where performing an actual fix is not an option, but sometimes a customer really just needs to get their equipment up and running again. Whether it is worth the risk of long-term damage beyond a small leak, is up to you but as a professional technician, you need to give your customer the facts. Fixing a leak now, by creating more headaches in the future is not a good solution.