Leak testing?

[slavic1705]

Hello I've been around for a while I just don't post much. I bought a chilly1 kit and put it together and promptly killed my MB a couple weeks later due to bad insulation on the back. Well I ordered a new MB and went back to air till I was brave enough to try again. I went to turn the system on a couple of weeks ago and found that it was very low on refrigerant so I guess I have a slow leak. Due to my lack of knowledge on brazing I used the wrong sort of brazing rod for MAPP gas and had to heat things for about 20 min and barely had enough heat to get a good braze. This frustrated me and I ended up having a friend of mine (a HAVC) do the rest so I am guessing its one of mine. I'm going to try and find my leak tomarrow and I have a few questions.

1. I now have 15% silver brazing rods which seem to work much better.
2. I've already checked for oil and can't find any.
2. What is the best why to find a slow leak? (soap and water?)
3. Do I really need to do an over-night evac to charge the system and test for leaks, or can I just do it for a couple of hours?
4. 300psi when testing?

Thanks!

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http://img67.imageshack.us/img67/732/1001478nv1.th.jpg (http://img67.imageshack.us/my.php?image=1001478nv1.jpg)
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[boshuter]

If the system is discharged I usually pressurize it with nitrogen, 300psi is plenty the more pressure the easier it will be to find the leak. Soapy water works well on joints. I usually stick the evap and a section of the suction line in a container of water, that will quickly show any leaking in the brazing of the evap.

[[XC] 2long4u]

Mr Bubbles!

[n00b 0f l337]

OT: Tiny condenser :( You sure thats sized up to par?

[slavic1705]

Is there some reason why you use nitrogen or can I just charge it with some cheap refrigerant?

I thought the condenser was a little small when I bought it but it seemed to work for the couple of weeks I had it up and running. I have thought about buying a new one from under-the-ice but it has to fit in that Lian Li V2100B behind it. So if I was to buy a new condenser I think I would need to hack it all up and start over. I was in to much of a freaking hurry last time and did not think the layout through.

What should I do?
:shrug:

[boshuter]

Is there some reason why you use nitrogen or can I just charge it with some cheap refrigerant?

Unless you have a recovery machine you would have to vent the refrigerant to atmosphere, and it's not going to be easy to get 300psi using refrigerant. Your best bet is to let your HVAC friend fill it with nitrogen (he should definitely have some). CO2 would also work well.

BTW... you probably don't need 300psi to find the leak, but if it's never been pressure tested, it sure wouldn't hurt to see if it would hold it. ;)