not that cool!

[sawman]

I have recently obtained a '98 C280, I am not convinced that the air con is functioning properly - the digital display and all the buttons appear to function correctly, but I wouldnt say its hugely cold, and there doent seem to be much difference with the EC button pressed.

does this just need regassing or is there another issue?

 

[AndyPCD]

By the sounds of it i would say it needs regassing.

 

[sawman]

Doh! just popped in to ATS while passing and they tried to regas the system, but it failed the leak test - the guy said he couldn't see the leak with his UV dye.

Are there known weak areas in the system, and is it likely to be a cheap or expensive fix??

 

[johnsco]

The component that fails most-often is the heat exchanger placed behind the air con electric fans and in front of the main radiator.
This takes all the rubbish that comes into the front of the car ... stones - weather, etc.
Usually you will see the leak in this unit if you view it in a darkened area with a UV lamp. A fluorescent dye is added to the oil in the air con system, and this shines a bright green/yellow colour under UV light.

I would imagine that the ATS guy has done this test ..... ???
Did he pressurize the system and add the dye ?
If not ... or ... If the system has not worked for a long time (or if no fluorescent dye was added last time), then he would not have detected the leak.

Other parts of the system can leak ... pump seals, connections ... or the evaporator.
If it is the evaporator, it is difficult to get at and usually expensive to change.

 

[sawman]

I guess this is the test he did, presumably he would have needed to try to pressurize the system to test for a leak - he said that the leak test failed, that he couldnt see an obvious UV dye leak and that i should take the car to a specialist.

I didn't watch him doing it, as there is a nice cafe next door!

 

[johnsco]

The first thing he would have done is to vacuum the system down.
This would have told him that there was a leak.
If the system did not vac down, it's possible he might not have gone on to pressurize it.
Only by pressurizing it with the fluorescent dye added can you detect a leak with the UV lamp.
I did my E300TD recently in this way.
As usual, it was the front heat exchanger..
There was a big fluorescent glow from the centre of the core.

The problem is that, if it is the evaporator unit, I'm not sure how you could see it, as it's well-buried.
Hope it's something simple.

 

[sawman]

cheers, I'll have a snoop around the condensor - looks like they are reasonably cheap to replace if needs be, but if its anything more than that I'll stick with opening windows when its hot - its only a 600 quid car!

 

[johnsco]

It's very easy to throw a lot of money at air-con on old cars.
Trust me ... I've done it !!