pressure test on aircon after seal replacement

[tim_pato]

My ute had no gas in the aircon when i got it. If i take the seals out of a system that was holding fine and put them in my ute, can i pump the system up with a compressor to see if it holds pressure?

[Herrod Motorsport]

You need to hold it in a vacuum not pressure

[aussiblue]

Used seals will leak as they conform to the fittings they were used in and will hold that slightly distorted shape. Buy new ones as they are cheap enough. e.g. :

http://www.ebay.com.au/itm/O-ring-ki...item3cca03464e

http://www.ebay.com.au/itm/FJC-4278-...item5d2951258f

You also need to lube the O ring seals with compressor oil before fitting them and torque the fittings to spec.

Compressed air will also add water into the system that you don't want (it very quickly causes corrosion and leaks). For this reason leak testing of an empty system is usually done by filling with oxygen free dry Nitrogen gas. Your best bet is to get whatever shop that is going to refill the system to also do the dry nitrogen gas leak test first. Before the refill vacuum will then be applied for around 30 minutes to remove any air or moisture from the lines not to test for leaks.

In addition to being environmentally friendly and much more visible when it leaks, the smaller nitrogen molecules will detect leaks that air con gas will also escape through but not the larger air and water molecules.

[tim_pato]

Ok thanks.

[aussiblue]

Here's another good reason not to use compressed air:

DO NOT USE COMPRESSED AIR to test for leaks. Even a system without refrigerant will still contain oil. Oil and compressed air = possible explosion.

http://www.etcs.pwp.blueyonder.co.uk/msg1.htm