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I've had my GS300h (2014) for 18 months and it has done only some 33000 miles. Last summer the aircon had to be regassed (local non-Lexus garage) and has today, after some 6 weeks of lockdown non-use, failed to work yet again. Grateful for any useful suggestions (I've googled and seen that this has the potential to be an expensive issue.



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Hi Tony.
It sounds like you Lexus has a minor leak of the AC gas. There are possibly two ways of dealing with this.
The first is to have the system re- gassed, and have a special dye put in at the same time. This dye shows up under ultra violet light so that any leak can be traced,  repaired, and then re-gassed again.
The second way is to have an AC leak sealant put into the system when it is re-gassed. This only works on minor leaks "as yours is likely to be as it took some time to stop working" , and works by a special chemical sealing the leak as it meets oxygen from the atmosphere, and cannot clog the system in any way. This can be very effective.
I hope this helps.


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When I revived the AC on my IS220D I had a company called cool car come out to me and test the AC system for leaks. They used an electronic sniffer like tool. It went mad when around the condenser. I fitted a new one and had it regassed. Working AC. 

The cost for test was £30.00.


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Unfortunately aircon gas tends to leak if the system is not used - because it is purposefully switched off in the mistaken beliefs that it is not needed during the winter or that it increases fuel consumption - or as now, due to long term non-use of the car at all.

It is a legal requirement that aircon systems be checked for leaks during the regas process - the old gas is pumped out, then the system is filled with nitrogen and checked for pressure loss, then the nitrogen is removed and the system refilled with the specified amount of R134a. (Or as James said, a leak detector can be used)  Sadly, cowboy operators often miss the pressure check part.

One cause of aircon systems not working is because they are frequently overfilled at the factory - they just hook up the gas source and open the valve for a sort-of-known time - my IS250 had nearly twice the amount of gas it should have had when it stopped working. I have heard of vehicles even more overfilled than that.

So I would say - get it refilled properly, including the pressure check and make sure the operator knows how much gas is required for the refill. And use the aircon on at least a weekly basis - in fact keep it on permanently. (when the car is running).

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