Thread: Pantina-like corrosion on condenser coil

Noted this condition on an outdoor coil of a 2001 Bryant unit.
The house was located close to a road that gets moderate-to-heavy traffic, but otherwise the home, the unit, etc. etc. was not atypical.

If it were the indoor coil I might lean towards Chinese drywall suspicions, but outside?
Any thoughts as to whether this pantina-like corrosion is of concern?

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Originally Posted by Dave Hahn

Noted this condition on an outdoor coil of a 2001 Bryant unit.
The house was located close to a road that gets moderate-to-heavy traffic, but otherwise the home, the unit, etc. etc. was not atypical.

If it were the indoor coil I might lean towards Chinese drywall suspicions, but outside?
Any thoughts as to whether this pantina-like corrosion is of concern?

Yard chemicals or the coils were cleaned and not washed well.

Environmental pollution, acid rain.

I think I would word it a little stronger than "Patina".
Something like "Evidence of corrosion..."

An overly zealous or non-too-careful encapsulated long-acting residual pest control applicator, or a wall or roof washer; who didn't immediately flush the area while still wet and a condensor in a semi-protected location.

If I was a betting man I would go with the misuse of a coil cleaning product. Some of the chemical cleaners for condenser coils are acidic and are to be diluted before being applied. Some service people however may skip that step and spray it on full strength, and maybe even let it sit for a while before rinsing just for good measure. Would be easy enough to get some overspray onto the copper tubing resulting in the discoloration that you see in the photo.

Really tall dog...

I would call for professional evaluation and servicing prior to closing.

Originally Posted by Scott Patterson

Yard chemicals or the coils were cleaned and not washed well.

x2 on the fertilizer. Those pipes can sweat too.

I might make a note, but not as big of an issue as the coils them self. What do they look like?


FWIW, I used some copper pipe for a garden project. I mixed up some fertilizer and water, and then coated the copper pipe to make it turn green.

Look directly up over the unit, You will see an overhang of the roof. No gutter, or clogged gutter would be probable. Unit also runs in winter being a heat pump, so it sees some harsh conditions.

What did the coil fins look like. You would think the chemical would eat off the coating on the fins.
David Bell, you forgot to mention if a heat pump is under a eave a gutter is required. Water dumping into the unit will freeze up like a ice cube even with heater coil. Can't find my picture of a ice cube heat pump I saw awhile back.