That is a hard one, the best way is obviously to walk up and look at the label to see the manufacturing dates, and check coils and lines, but since you can't, this is the next best thing:

Ashurst Air Street-Level Clues for Bad or Failing AC Units

Rust Stains: Rust on the wall or pad usually means heavy corrosion.
Tilted or Damaged Unit: If the condenser looks sunken, uneven, or has missing panels, it's likely neglected.
Faded Metal: Chalky or discolored housing often points to UV and weather damage.
Unusual Setup: Window units often mean central AC is broken or missing. If the condenser is gone but capped copper lines are visible, it may have been removed or stolen.
Signs of Theft: Look for snipped lines or broken AC cages — common signs of scrap theft.
General Neglect: Poor roof, paint, or landscaping usually means HVAC got the same treatment.

Hi Frank,

Great question. A/C is a serious cost factor that can really impact your budget and profits in this business, especially here in Florida. There are a few things you should keep in mind when you can’t physically inspect the system before auction.

If it’s a single-family home or a townhome, try to spot the exterior A/C unit. Now that we’re in spring heading into summer, if the unit is at least operational, it should be kicking on every few minutes, even if no one is living there. That’s because mold is a constant threat in Florida, and most owners keep the A/C running to prevent it. Look for signs like rust, corrosion, leaks, missing panels, or signs of tampering. These clues can tell you a lot about whether the unit has been maintained or abandoned.

For condos, it's a bit more complicated. If it uses wall units, you can sometimes inspect them from the outside or through the windows. Condensation or dripping water can also indicate that the system is currently running. If it's a central system with a rooftop condenser, access can be tough, but not impossible if you get creative.

That brings me to some alternative ways to gather info without stepping on the property:

FPL (Florida Power & Light): Try checking the FPL website to see if you can start a new account at the property. If it lets you proceed, the power is likely disconnected, and that usually means mold risk and an A/C unit that’s either off or needs work. If there’s already an active account, chances are good the A/C is still functional, maybe not perfect, but not dead either.

Drone footage: A drone can be a game-changer. It lets you inspect roof-mounted systems or see inside gated communities or upper-floor condo units that are otherwise off-limits.

Ask the neighbors: Don’t underestimate this one. A quick chat with a neighbor can reveal things you won’t find anywhere else, like whether the place has been sitting vacant with no A/C for months.

That said, no matter what, always set aside a buffer in your budget for A/C repairs or replacement. We’re in South Florida, functioning air conditioning isn’t optional here, it’s part of the game.

Hope that helps,