Hi I have a AE92 and today I went to get the air con re-gassed, but unfortunantly there was a small hair line crack where the air conditioning lines connect to the condenser just behind the right headlight. The hair line crack is about 10-15mm long and starts from the lip. Tried a thicker o ring but still leaking slightly. Is there anything out there or a product that can repair the crack such as aluminum welding it from the outside? or should I just replace the condenser?

Replace the condensor and the lines. The gas is under pressure, repare one crack and it will find the next weakest point, and it's always around the connections.

The lines are made of aluminum, the connection are made of God knows what, and corrosion is a common problem.

I've just been through this with my Holden, it wasn't very expensive to replace the condensor and lines, but worth it.