How much to tighten O-ring fittings

[Osiris610]

How tight should I make automobile O-ring A/C fittings? Is finger-tight enough?

Thanks, Mike Whalen

[Cusser]

I do tighter than finger tight, but not gorilla; so that's not much help.

With an O-ring, the compression forces the O-ring to expand and seal. So I'm saying firm, and when you pull a vacuum or check with bubble solution after refrigerant fill, you should know if you need to tighten a tad more.

Use new refrigeration O-rings only, and oil them with a small amount of refrigeration oil before installing.

[Osiris610]

Just what I needed to know. Thanks!

[pete_89t2]

One other point you need to know about installing O-rings is to never install them dry. Always lube them with whatever compressor oil your AC system uses prior to installation.