'72 AC evaporator inlet case - rust holes in inlet case back plate

[Randall K.]

Anyone have a suggestion on how to repair rust holes in the inlet case back plate - or where to find a replacement back plate?

Rust holes are relatively small (half inch and less), and where the back plate meets the fiberglass of the evaporator case, toward the bottom (probably accumulated moisture over the years).

Thanks
Randy

[Chuck S.]

Re: '72 AC evaporator inlet case - rust holes in inlet case back plate

Anyone have a suggestion on how to repair rust holes in the inlet case back plate - or where to find a replacement back plate?

Rust holes are relatively small (half inch and less), and where the back plate meets the fiberglass of the evaporator case, toward the bottom (probably accumulated moisture over the years...

Randall, since this component is not visible, there are any number of ways to make this repair. I'm sure you'll get plenty of ideas here.

I also had to repair my back plate, and think I used fiberglass cloth and resin that I had on hand. If I call correctly, there was general corrosion along the bottom edge of the plate where leaves, stems and other debris had accumulated and held moisture in close contact with the steel for extended periods of time. Use of steel for that component was probably a bad idea, but universal use of plastic was still a ways away.

Whatever materials are used, I would use something that doesn't rust; e.g. another idea is to cut aluminum flashing into appropriately sized patches, stick a patch over the hole with 50 yr acrylic latex or silcone caulk, then drill the corners of the patch for aluminum pop rivets to make sure the patch won't EVER come off.

Depending on the approach to the repair, bead blasting followed by a couple coats of epoxy primer would be a very good idea...hopefully, you won't be going back in there soon.

[Randall K.]

Re: '72 AC evaporator inlet case - rust holes in inlet case back plate

Hello Chuck - thanks for the input. I was also considering fiberglass, as I've got some on hand from the repair I made to the other half of the evaporator case. Stuff sticks to anything/everything as long as the surface is clean, so I think I'll do this one outside on Sunday while it's still relatively warm in St. Louis!

Thanks
Randy