Rick's Free Auto Repair Advice

Reasons to avoid AC recharge kits

Don’t use a DIY AC recharge kit to fix your car’s AC

Most DIY AC recharge kits come with a container of R-134a refrigerant, a low pressure gauge and a low pressure quick connector. The can is filled with the R-134a refrigerant, oil and stop leak sealer. From the consumer’s point of view, this is all you need to get your car’s AC up and running again. But beware, the AC recharge you performed today may actually be setting you up for a much more expensive repair down the road. Here’s why.

 If your AC system is low, you’ve got a leak and the AC recharge kit probably won’t fix it.

All engines burn some amount of oil, but AC systems don’t use up refrigerant. Ever. If the system is low on refrigerant, it’s because some of it leaked out. No big deal, you say? Well, there’s two key issues to consider when it comes to refrigerant leaks; 1) the refrigerant carries oil throughout the system and that oil lubricates the compressor pistons. When refrigerant leaks out, some amount of oil goes with it. Then you’re operating the system when it’s low on oil and that causes premature compressor wear. 2) Whenever an AC system leaks, air and moisture enters the system and that’s a much bigger problem.

Moisture kills AC systems

Moisture is the enemy of an AC system. It reacts with the refrigerant and oil to form destructive acids and sludge. The sludge coats the internal passages of the condenser and evaporator coils, reducing their ability to transfer heat. The acids also eats away at critical internal seals, causing early failure. Finally, when liquid refrigerant is metered by the expansion valve or orifice tube, moisture can cause an ice formation that slows or blocks the refrigerant flow. That causes the system to run cold, then warm, then cold again.

Air in the system may compress like the vaporized refrigerant, but it doesn’t boil and vaporize like refrigerant. So even though it takes up the space, it doesn’t provide any cooling. If there’s 20% air in the system, you will never get the same amount of cooling as a comparable system with no air. In other words, it’s never work properly.

What’s the proper way to fix an AC leak?

The only way fix an AC leak is to locate it and fix it with new O-rings, hose or metal components. Once the leak isrepaired, the shop will examine the system to see if there’s sludge buildup caused by acid and lubrication breakdown. In some cases they can remove the sludge by flushing the component. In other cases they must replace the compromised components. Then they evacuate the system to remove all remaining moisture. Next, they add the factory recommended oil and refill the refrigerant using a special refrigerant scale. So you wind up with the proper amount of oil and a dry system that works like it came from the factory; something a DIY recharge kit can never accomplish.

The stop leak sealer in DIY recharge kits rarely works

Lots of companies make leak sealers for power steering systems, engines and transmissions. Most of the time, the sealers are actually just seal swelling compounds that soften hardened rubber seals so they can work longer. That’s not how AC stop leak sealers work.

AC stop leak sealer works by venting out of a pinhole leak in a metal component and coming into contact with humidity in the outside air. The humidity causes the sealer to harden and form a scab over the pinhole leak, thus resealing the system. (Remember this for later!) Sounds good, right? Unfortunately, most AC leaks aren’t in metal components, they’re caused by aging rubber O-ring seals at the condenser, evaporator and compressor connections. Even if the sealer manages to form a scab on an O-ring, the fix won’t last because the rubber flexes with temperature changes and the scab breaks off.

Leak sealer will always come back to bite you in the butt

Remember the part about how leak sealer hardens when it comes into contact with moisture? Well, since most stop leak fixes fail over time, you’re going to have to fix the leak properly at some point. When you finally roll into the shop to have it fixed, the shop will have to remove all the refrigerant from your system, and that refrigerant is now contaminated with stop leak sealer that will damage the shop’s recycling machine if it isn’t filtered out first. Guess who’s going to pay to have the leak sealer filtered out? Yeah, you. So, in reality, that DIY recharge kit didn’t permanently fix the leak and now you not only have to pay to have it fixed the right way, but you also have to pay an upcharge to remove the contaminated refrigerant. Worse yet, you’ve been running the system with air and moisture all this time and it has degraded the internal components.

Lastly, most DIYers misuse AC recharge kits

An AC recharge is always done by weight, not pressure. But DIY AC recharge kits only contain a pressure gauge. So even though you’re adding refrigerant to the system, you will never know exactly how low the system was or exactly how much you’re adding. Studies show that most DIYers overcharge their AC systems when using an AC recharge kit. And, when it comes to R-134a refrigerant, more is NOT better. Overcharging by as little as 2-oz. can dramatically decrease the overall performance of your car’s AC system.

Bottom line on DIY AC recharge kits

You spend $40 on a kit to make your AC work for a while. But since you never fixed the underlying problem, the recharge won’t last. In the meantime, the acid formation and sludge buildup (caused by air and moisture in the system) continue to degrade seals and wear out compressor parts. To add insult to injury, when you finally bite the bullet and take it to a shop, you’ll have to pay an upcharge to remove the contaminated refrigerant/sealer from the system.

©, 2019 Rick Muscoplat

Posted on by Rick Muscoplat

Custom Wordpress Website created by Wizzy Wig Web Design, Minneapolis MN