Air con pipe problem

M0T · 25 Oct 2007 at 14:39

I had to replace my air con rad as it had over 6 holes in it, so instead of forking out £200 for a new one I bought a one from a scrap car for £20 inc delivery.

When I took the old one out I discovered that one of the pipes connecting to the rad (metal) had snapped off, so I needed a new one of those as well (£50).

The guy that sold me the scrap rad left this pipe on for me, for no extra cash, but for some reason bent it back over the radiator so it would fit in a shipping box, instead of just removing it with an allen key.

I have bent the pipe back to the correct shape, but obviously its now got stress lines along the bend point, as it is quite brittle metal and was never meant to be bent like that.

It doesn't appear to be leaking (using an unscientific blow test), but I am worried about gassing up the system if it is just going to leak out because of stress fractures in the pipe.

Is there anything I could put over these stress lines to stop it from leaking (would epoxy work?)?

Ian_Eb · 25 Oct 2007 at 19:29

Depending on the gas used the pressures can be quite high ( > 100psi on the discharge side)

I wouldnt be too happy about it myself as there is a fair chance of it leaking straight off.

BigglesPiP · 25 Oct 2007 at 19:48

You could try some kind of heating process, not sure whether quenching it or allowing it to cool would be better tho?

tb2000 · 25 Oct 2007 at 20:56

I'm not sure how it would work, but you could clean the area affected and tin it with solder. Make sure the metal isn't so thin that it melts like the solder though! They use solder to repair radiators so it should be strong enough.

Dave L · 27 Oct 2007 at 08:30

I expect it'll be fine.

Unluckyalf · 27 Oct 2007 at 09:50

I am fairly sure that modern aircon gasses have a dye in it to show up leaks. Just straighen the pipe out, fit it and get it gassed. Once under pressure you shoud see instantly if its holding

Dave L · 27 Oct 2007 at 10:25

No, the gas is colourless and odourless - a flourescent dye can be added to the system to aid leak diagnosis.

Ian_Eb · 27 Oct 2007 at 16:07

Not that anyone would ever catch you, but there are big fines for knowingly releasing any of the current refrigerants into the atmosphere.

If you have a leak, then thats ok, but it must be repaired and retested before attempting to recharge the system.

http://eur-lex.europa.eu/LexUriServ/site/en/oj/2006/l_161/l_16120060614en00120018.pdf

tb2000 · 27 Oct 2007 at 16:17

Unluckyalf said:
I am fairly sure that modern aircon gasses have a dye in it to show up leaks. Just straighen the pipe out, fit it and get it gassed. Once under pressure you shoud see instantly if its holding

Indeed, most automatic machines that re-gas vehicles test the system to see if it will hold pressure anyway though. I know that at least the one at the business I use has a sequence for air-con. First it empties any old gas and oil (for pump lubrication) from the system, then it does a pressure test to make sure it holds pressure. Then if that passes it will fill the system up with new stuff, usually cost's me about £45. If it doesn't pass the pressure test no new gas is pumped in and they don't charge you. I spoke to the bloke who did me car once and he reckoned the leak would have to be pretty small for the machine not to detect it. Saying that, we had my dads Xantia regassed ages ago and it lost the gas over a period of about 4 or 5 months so it must've had a leak smaller than the machine could find!