I have been wanting to purchase a spare 79 HVAC with air and no rear defrost. I have been looking but have not found one until recently.
I did find one but the mechanisms were rusty. I just wanted the face and I could have stored it this way, but in my mind storing a rusty part bugged me.
So I thought I would use Evaporust.
Before
AfterIt is shiny because I sprayed it with WD-40 to protect from flash rust. I am letting it air out for the day and then in a zip-lock bag.