Beware the DIY aircon re-gas and leak sealant

So, your air conditioner doesn’t feel as cold as it used to and you’ve heard about DIY re-gas kits and canned sealants that are available through accessories supermarkets and on-line. Can we suggest you read this article first!

One of our truck journo mates, Howard Shanks, told us of his son’s recent experience, repairing the aircon units in several vehicles, whose owners had bought re-gas cylinders and did their own aircon repairs.

Shanksy’s son, Tom, runs Queensland-based Master Tech Diagnostics and Repairs. He’s a qualified auto electrician and is a licensed aircon technician, with more than 15 years experience in both trades.

Most vehicle owners don’t have the manufacturer-recommended annual aircon system health check and performance issues with aircon units usually don’t become a problem until the warmer weather arrives. 

It’s obviously tempting to think that topping up the aircon system gas will improve performance and not many people know that unlicensed work on aircon systems is actually illegal. The reason for that are the high risk of fire and potential release of polluting gases into the atmosphere.

During Shanksy’s recent visit to his son’s workshop, Tom answered the office phone and listened to the caller explain his problem before saying:

“OK, bring it around, and we’ll look at it for you.” Then he hung up the phone.

“At least this guy called before attempting a DIY air conditioning repair,” Tom sighed with relief. 

“Doing a DIY aircon fix might seem like a good idea and a way to save a few dollars, but it’s false economy, because taking the vehicle to a reputable air conditioner repair workshop is easier and cheaper in the long run.” 

Topping up the refrigerant without identifying the root cause of the issue may provide only a temporary solution, masking underlying problems, including leaks and component failures.

In the two weeks before OTA published this report, Master Tech Diagnostics and Repairs had to replace the AC units on four vehicles because drivers had attempted to top up their systems with incorrect gas. These guys each spent around $150-$200 at cheap-parts stores on cans of gas to refill their AC systems.

DIY enthusiasts rely on generic top-up cans that readily available these days. Using a differing-specification refrigerant type or incorrect quantity of gas won’t work and can cause significant damage and a high risk of injury during the procedure. 

An example of incorrect application is using M30 hydrocarbon – more affordable than R134a or R1234yf –  but, unlike these manufacturer-recommended gases, is highly flammable. If you’re topping up refrigerant gas using a hydrocarbon gas, there’s a high probability of fire. Also, in the event of a collision that causes damage to the AC system, flammable gas could be released inside the cabin.

Your vehicle’s air conditioning system was designed to work with the recommended inert gas and has rubber and aluminium components that are not compatible with highly flammable gas; especially at the high pressure required by the aircon system. Using incorrect gas in your vehicle’s air conditioner system could also impair the circulation of lubricating oil, causing damage to internal parts and creating the risk of a gas leak.

Overcharging the air conditioning system is a common mistake made during DIY maintenance, even if the correct gas is used. This can result in increased pressure levels, compromising the integrity of components and risking system failure. Licensed professionals are trained to measure and charge the system within manufacturer specifications accurately.

DIY top-up cans often come with imprecise pressure gauges, making it challenging to accurately measure and regulate the system’s pressure. Notably, this can lead to overcharging or undercharging, jeopardising the performance and longevity of the air conditioning system.

Tom also warned that DIY top-up cans offer no guarantee of success in resolving air conditioning issues: 

“Without proper diagnosis and repairs, the problems may persist, leading to more significant expenses in the long run. 

“If you manage to top up the AC system gas without burning yourself, damaging parts or breaking the law, the fix will likely only be temporary – because the original leak, which caused the air conditioner system to be low on gas in the first place, has yet to be fixed. 

“You’ll still need to take the vehicle to a licensed technician, to have the cause of the leak located and properly repaired.”

A copy of one of Master Tech Diagnostics and Repairs recent aircon repair jobs told its own story:

“Look at the invoice this poor fella had to pay last week to have a new AC system fitted into his truck, because he tried to save a few dollars,“ said Tom.

“He spent $400 on two top-up cans, which destroyed the AC system in a matter of minutes; then spent another $2800 with us installing a new AC unit.”

“If he had seen us first, we could have rectified the issue and re-gassed the system, for about $1000, including GST,” he added.

Aircon leak sealants

One of the most common forms of aircon performance failure is loss of refrigerant through a leak in the system. Generally, leaks occur at unions and seals, or in metal components of the system.

Leaks can be detected by professional regassing with dye infusion: the dye will show the location of any leaks. 

The correct approach to aircon system leaks is to replace the affected components, but that can be a time-consuming and expensive exercise. Removing and replacing parts can involve many labour hours, because evaporators and condensers can be difficult to access. Hence the temptation to use a canned sealant.

There are many aircon leak sealant products on the market. In general, sealants are aimed at either reconditioning hardened O-rings and rubber seals, or sealing tiny holes and cracks in metal evaporators and condensers.

Within that broad description are products that vary from cheap, quick-fix DIY products to expensive, professional-grade sealants intended for use by qualified aircon mechanics.

The DIY type can be discounted easily: don’t even think about using these yourself, because introducing a sealant into an aircon system that may need professional leak diagnosis and regassing will just make things worse: often through reaction with trapped moisture in the system.

Canned sealants that are intended to recondition O-rings and seals are generally based on ester oil. A quality sealant containing ester should not harm an R-134a aircon system, but should be administered by an aircon mechanic, who can determine what other procedure may be necessary.

The second leak-stop product is a chemical-based sealant, specifically formulated to plug leaks in metal components. This sealant reacts with moisture in the air at the site of a leak, where it congeals and, hopefully, stops the leak.

This type of sealant has earned itself a bad name, because if the system isn’t professionally purged of moisture, it can solidify in places where it shouldn’t, causing even more trouble. Top-quality sealants are warranted not to clog aircon systems, when used professionally.

The instructions supplied with top-shelf sealants spell out quite clearly what they’re intended to do and that was further clarified by the US maker of EasySeal products:

‘They’re not meant to replace the traditional method of finding and repairing leaks, but moreso for fixing microleaks that contractors would typically fix by topping the system off with a small amount of refrigerant every month or year.’

This point is very important, because sealants are not designed to repair more than extremely tiny leaks. If your aircon system has lost refrigerant within a few days of a recharge, a sealant will most likely do nothing to rectify the situation. Our real-world experience confirms that.