My Octavia has had its air con regassed for the 4th time in under 2 years. The dealer hasn't been able to find any leak. Once they replaced a faulty valve but that doesn't seem to have fixed it. It is okay for a few months after a re-gas but then you get a noise when it is on which i am told is the compressor running as there is no gas. They have put dye in previously but not found a leak. This time they have re-gassed it and put more dye. I will take it back in a couple of weeks to see if they can spot a leak but I'm not hopeful (on past experience)

Wondered if anyone else had had a similar problem or any thoughts?

Thanks :confused:

The leak could well be around the evaporator or expansion valve (behind the dash and therefore not visible/accessible). I believe VAG have had problems with leaky evaporators on other models.

I had to have my compressor replaced under warrenty as I was told it would hold the gas for a bit then just dump it all somewhere, maybe an over pressure value or something I've no idea.

Possibly worth investigating with a UV dye fill this time.

I would expect a pressure test to be carried out, the leak might not be present until the discharge pressure rises while the system is running.

If the leak is indeed around the evaporator/expansion valve I would expect/hope to see some oil/UV dye around the condensate drain.

Off hand I don't know if there is a safety blow off valve on the fridge circuit to complement the high pressure switch, if there is it could be releasing at a lower pressure than it should.

Other than that it could be a pin hole in the condenser (stone damage),

a split in one of the refrigerant hoses/pipes that snake around the engine bay or

a dodgy compressor seal. Fingers crossed there will be some UV dye in the belly pan or something similar when they check.

I had a similar problem with an Astra after 2 years/50K miles - it was due to a leaking condenser. Apparently condenser failure is a common problem on most makes.

Sometimes the dealer will not have the required equipment to correctly locate and dianose the fault. What you need is a proper car aircon specialist who do this kind of fault finding everyday as part of their job. They have all the correct equipment, pressure testing stuff, dyes and so on. I had a leak on my Boxster A/C and it took a specialist to locate it.

The process usually goes along the lines of.

1) evacuate all the gas currently in the system, if any still their,

2) pressurise to a known good pressure slightly above normal operating pressure. Leave for around 30-40 mins and note any loss.

3) if loss is apparent, then refill the system with normal refrigerant and add U/V sensitve dye to aid finding the leak.

4) if the leak noted in 2 is slow, then go home and drive around until the a/c stops working again.

5) specialist will now go over the car with a UV lamp (under the car, inside, basically all over to locate the leak.

6) repair, if neccessary change the reciever/dryer and refill the system with normal gas.

The leak on my Boxster was so small it took several months for step 3/4 and yet he was still able to find a small leak that the dealer could not locate and never neaded refilling again afterwards.

What i know was mine lost all gas, they checked it and regasseds then the next day it was gone again. They mentioned something about a weak spring in the compressor I think, and as I said it was replaced under warranty. No problems since touch wood.

Well guess what - car went back into the garage after it had been regassed and UV dye added and no leak was found!

No response apart from carrying on using it as normal and see what happens!

Well guess what - car went back into the garage after it had been regassed and UV dye added and no leak was found!

No response apart from carrying on using it as normal and see what happens!

No leak found YET!

You only have a small leak. Suggest you take it back after a week or so of running and have them check again.

take it to another skoda garage. this is not a hard job!! obviosly not trained/or have the proper equipment. will the system hold a vacume, obviosly not because the gas is missing, i know this sounds stupid but when the dye is put in the system do they have the uv lamp and glasses to actually see the leak, if they do they must be blind!! please take elsewhere..............

It could be the low-pressure port. If they don't have much experience of A/C they may well exclude this as this is where they injected the dye. If you have run the A/C for week with the dye in, then even a small leak would light up like a flare under UV.

Agree with fireblade - after 4 visits it should be fixed (with or without UV dye) - go somewhere else.

Get someone else to have a look at it dye is usualy easy to see even without a uv light i have had quite a few leaks from the pressure sensor, or it could be a leak from the strainer valves on the filling ports most people ignore the dye present on them cos thats were you put it in!!!!!

UV dye can be surprisingly difficult to see even with the UV lamp, the yellow glasses are also needed to ensure the best chance of seeing it. Also, the glasses filter out the dangerous levels of UV produced by the lamp which is particularly bad for the Retina.

The service ports usually have caps with rubber seals, check both seals are intact.