Thread: What's Causing this Damage to A/C Unit Fins?

This is an Amana VCA30C2C (SELECT -10 SEER COND.) unit manufactured in 2004, which has severe fin corrosion, but only on the bottom inch or two of unit (see photos)--what is causing this? A very short dog?

IMG_20161011_150443 - Copy.jpgIMG_20161011_150443.jpgIMG_20161011_150448.jpg

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Photos won't open, but usually its animal urine.

Photo worked for me. Jack is right. Looks like dog pee.

Dog pee….

i'm going with snow/deicing treatment materials based on OP location & fairly uniform damage to all lower surfaces visible
https://www.epatest.com/EdArticles/P...%20CoilCor.pdf

Given the location of the corrosion and your location in the profile, I'm guessing de-icer such as salt from the deck. No matter though, that a/c unit is at the end of its life, it needs to be replaced soon and caution against using chemicals (or short dogs) around the unit.

I am in sunny California and we don't have snow (well... in the mountains, but not where I live) and I never thought of de-icing salt or chemicals. When I see dog pee, it is more random and higher up on the fins than what I see in your pic. Barry's & Jim's explanations seem more likely than a dog with good aim.

Two Types of Environmental Corrosion - bottom page 1
https://www.epatest.com/EdArticles/P...%20CoilCor.pdf

1: Compressor clearance.
Not above the grade or surroundings.

2: Damage from animal or rodents.
Look at the gnawing or marks on the wooden chair leg.

ac damage.jpg

Just my 2 cents.

Dog piss

Being that the compressor sits below the deck and the corrosion is at or slightly above deck, I'm thinking either pressure washing or corrosives in deck cleaner or both. Doesn't look like urine to me.

Has anyone considered leaching of the PT chemicals by rain splash? Crap, just about anything will react and deteriorate AL.

Originally Posted by Ian Page

Being that the compressor sits below the deck and the corrosion is at or slightly above deck, I'm thinking either pressure washing or corrosives in deck cleaner or both. Doesn't look like urine to me.

Pressure washing makes sense. Damage is more mechanical than chemical. I had a dog that destroyed a corner of my compressor and it doesn't look anything like that. It may also be something like regular sweeping on the deck bumping the unit.

Originally Posted by Lon Henderson

Pressure washing makes sense. Damage is more mechanical than chemical. I had a dog that destroyed a corner of my compressor and it doesn't look anything like that. It may also be something like regular sweeping on the deck bumping the unit.

Yes Lon...look at the damage to the leg of the wooden stand next to the compressor. That's very consistent with aggressive pressure washing. Been there, done that!

Originally Posted by Ian Page

Yes Lon...look at the damage to the leg of the wooden stand next to the compressor. That's very consistent with aggressive pressure washing. Been there, done that!

IMO, a pressure washer stream would have blown away aluminum particles in the compressor's pan and removed loose and badly damaged fins form the coil. I could be wrong though.

Ian, look at the damage to the leg of the wooden stand next to the compressor. Some of the damage appears to have been contrived by a sharp object. A hand knife or small hatchet.

hvac fins.JPG

The compressor is situated below the wood deck.
This goes against a manufactures clearance recommendations.

Also, this mostly enclosed reassessed area for the compressor acts like a basin.
The OP is situated in Wisconsin. Snow and ice will accumulate in that recessed area surrounding the bottom of the HVAC compressor.
As winter moves forward snow is compacted into thick layers.
Thaws would allow ice to form on top of snow pies entrapping the lower part of the cabinet.
Water expands up to 9% it's volume when frozen, minus oxygen and minerals.
With the majority of damage at or below the decks wood flooring, I suspect it is seasonal damage from avoiding clearance recommendations.

It is a poorly sited unit.
Given the location of all the corrosion essentially below the level of the deck, I'd say splash from the PT deck. PT & aluminum don't mix.

There's no corrosion above the level of the deck, essentially, which makes it unlikely to be a critters or urine, IMO.

Honestly, it sort of doesn't matter: the unit needs to be replaced, and should be elevated to be above the deck when it is. So it won't matter going forward...