Have a R410a Trane HP that has developed a moderately slow leak due to the OD TXV rubbing up against one of the aluminum tubes of the spine-fin OD coil. I've seen a few aluminum coil failures over the years, but those were on older equipment and resulted in replacements. This is an '06 unit that deserves many more years of operation - and the leak is actually more of a weakening, not completely worn through to open a gaping hole, but more or less has worn through enough to weaken the integrity of the tubing resulting in some small, fine cracks.
Anyways, I've always heard of some epoxy that can be used with a very fast cure time, so that the repair can be done in one trip. I've called a few suppliers and all of them have told me their refrigeration guys just use JB weld. Its been a while since I've used JB but I'm pretty sure it requires a 24 hour cure. I'd like to get the repair done in one trip, and also this client is fairly elderly and I don't want to leave her without cooling for a day. I did a search and found a couple of products mentioned, just want an updated opinion on what would be the best route in this case - being 410a with the higher operating pressures... If JB would be best I'm sure I can make arrangements once our little heat wave here in the PNW passes. Thanks for any input provided.