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It may work, but it probably won't, says an expert.


So, your air conditioner doesn’t feel as cold as it used to and you’ve heard about DIY re-gas kits 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 truck 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 houses 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.



























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