Can you paint an AC condenser?

[Daryl Chesterman]

Has anyone tried POR-15?  On their website they say it can be used for radiators, but says nothing about condensers.  It might be worth a call to them.  The POR-15 would protect against rust in areas of the condenser where you can't brush off the rust.  It comes in gloss and semi-gloss black.  This is their contact page:
     
     https://por15.com/pages/contact

Daryl Chesterman

[79 Eldorado]

That looks like a steel condenser used in the mid to late 50's. If it's steel I think it must be. I saw one up close once and it was a multi-port tube made from round tubes brazed together. They then bent the series of round tubes into a serpentine design. Very cool they were doing that in the 50's.

The issue with you trying to remove the rust is you will never remove what you cannot see in the depth of the core. To do the job properly I suspect you would need to dunk the part and chemically clean it and then it should go through some rinse steps followed by a conversion coat, something like trivalent chrome, and ideally followed by e-coat. I have no idea where you could have that done but if you can find someone who can do it it would be well worth it.

Any spray paints typically only penetrate a modern condenser around 3mm of the depth (this is similar in construction to a modern condenser). Powder paint won't work well either because it will seek the closest ground. There are some pressure pulse powder systems, marginally better, but you really want e-coat with a liquid bath. No real issues with heat transfer if it's painted properly. You will increase the air side pressure drop by something like a percent or two.