Weird stain on exterior brick by AC

[Erby]

Y'all got any ideas what's causing this weird stain on the brick veneer behind the AC unit.

I'm stumped. Fungal growth? Chemical over spray?

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[Richard Moore]

??? The only way the stain makes sense (to me) in relation to the AC unit is if the fan was running in reverse, sucking down and blowing out the sides. Then it might be a warmth loving mold(?). BTW...is that just sitting on the dirt?

One other WAG would be a leak in the pressure line "misting" the wall.

And then it could be something totally unrelated that was sprayed on the wall before the AC was installed just to confuse future home inspectors.

"Weird stain on wall. Inspector not know why. Have HVAC guy check it out." Sometimes you just have to punt.

[Terence McCann]

Looks like a new(er) condensing unit. I wonder what was there before. My split system, for the master bedroom, has a condensing unit that draws air in the front and discharges out the rear but I don't see why air blowing on the exterior would cause a stain.

Acid cleaning an older condensing unit? Stuff we use to clean them with was pretty nasty.

[Ben H]

One other WAG would be a leak in the pressure line "misting" the wall.

Thats the first thing that came to mind.

[Terence McCann]

One other WAG would be a leak in the pressure line "misting" the wall.

Thats the first thing that came to mind.

Problem with that is a "mist" of that magnitude would run the unit out of gas within a day or so. At best these units only hold slight amount of refrigerant.

[Marc]

I'd go with Terry...some condenser coil cleaners will quickly etch your glasses or dissolve away skin tissue if you're not very careful. My guess is that some overspray hit the wall during a coil cleaning service call by a careless tech.

Marc

[waynesoper]

Mabey that Blue Meth barrel was sitting over there before they installed the A/C

[shadow67550]

It is most likely an oil stain from the A/C. Oil will blow out with the refrigerant (usually high side) when the tech either cut the lines when the old A/C was changed out or the had a service hose break. Any large loss of refrigerant will cause this.

Try spaying a test spot with a degreaser or soap to see if it will come off.

[Terence McCann]

It is most likely an oil stain from the A/C. Oil will blow out with the refrigerant (usually high side) when the tech either cut the lines when the old A/C was changed out or the had a service hose break. Any large loss of refrigerant will cause this.

Try spaying a test spot with a degreaser or soap to see if it will come off.

Even a major leak will not blow that much oil out. Even though oil tends to migrate throughout the refrigerant lines the majority will stay in the compressor. Good guess though.

[John Kogel]

I think it's a cold spot on the bricks, cold enough to cause condensation.

You guys call them AC units, we call them heat pumps. []

The "heat pump" is dumping cold air against the wall.

[Jerry Lozier]

I think it's a cold spot on the bricks, cold enough to cause condensation.

You guys call them AC units, we call them heat pumps. []

The "heat pump" is dumping cold air against the wall.

interesting: we call units that put out conditioned cool air only 'a/c'; a unit that can run in reverse to produce either heat or cool a 'heat pump'

[Jim Katen]

. . . The "heat pump" is dumping cold air against the wall.

Not unless its fan is running backwards.

[John Kogel]

I think it's a cold spot on the bricks, cold enough to cause condensation.

You guys call them AC units, we call them heat pumps. []

The "heat pump" is dumping cold air against the wall.

interesting: we call units that put out conditioned cool air only 'a/c'; a unit that can run in reverse to produce either heat or cool a 'heat pump'

Yeah, I meant that as a joke. We see a lot of heat pumps, but rarely an AC only unit. Different climate.

Anyway, if that unit in Erby's pic is AC only, I don't have a clue. []

[Erby]

It's a 15 year old American Standard AC only that's been sitting there since the house was built.

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[Michael Carson]

Mabey that Blue Meth barrel was sitting over there before they installed the A/C

Maybe the unit had bean burritos for dinner. [:-monkeyd[:-monkeyd