[Mark Saunders]

Does anyone out there have any hints on replacing 'O' rings in an aircon system? Car is series one 156 2.5. There is definitely a leak at the junction under and behind the radiator on the nearside. I can't tell which of the two junctions here it is and figure that if one 'o' ring is leaking through neglect, they probably all want to be done. I can get to these and those at the pump, condenser and filter easily enough, but I assume there are more at the cabin end of the system - where are they?

Also, any info on the rings themselves would be helpful - are they something I can source in a kit from Halfords or a plumbing store?

I also suspect there is a slight leak at the low pressure valve, as when the system was charged, I'd get a little hiss when I took the cover off, as if there was some pressure building up there.

When the system was charged last summer it was making some strange hissing and whooshing sounds, seemingly from behind the dashboard, which I suspect was the sound of the gas escaping - does anyone out there have any experience of this?

 

[davealfa11]

when air con was filled did they do a leak down test?

 

[Mark Saunders]

Yes. It had a couple of fills last summer and at each it had a vacuum 'scavenge' and a leak test. This showed no leaks, but still it leaked over the following weeks. As in my original post, I suspect the noise I hear is connected to this. To expand on that, at first you'd only get the noise for a couple of seconds just after the compressor kicked in, but over the course of summer it got worse.

I know there's a leak at the junctions I mentioned as there was dye coming out there after the last fill. There's no sign of a leak elsewhere. Assuming the leak is on the 'out' pipe, this junction is just before the orifice tube and I assume this section of the system is therefore subject to the highest pressure when the system is running. Thinking about it, there was no sign of dye at the valve, so maybe the pressure differential there is due to temperature rather than a leak.

Maybe I could just replace the 'O' rings at the suspect junction, but I thought that while the system is empty and I have the rings and a spanner in my hand, I might as well do the lot.

If anyone knows the spec of the 'O' rings, I can probably get the correct size from RS.

 

[davealfa11]

i would order them from alfa romeo be on safe side ,or order just one and measure it up ,then see if rs has them