AC not cooling in NYC: fix the window unit, or move to a mini-split?
Most NYC homes cool with window units, through-wall sleeves or, increasingly, ductless mini-splits. When one stops cooling, the fix might be a filter, or it might be the moment to upgrade. Here's how to decide.
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Emergency? Gas smell, CO alarm, fire, sparking or flooding: get to safety and call 911 first.
Quick checks for any AC
- Filter: a clogged filter is one of the most common causes of weak cooling. Clean or replace it.
- Coils: dirty or blocked outdoor coils, including the back of a window unit, can't shed heat.
- Ice on the coils: switch to fan-only to thaw, then fix the airflow problem (often the filter).
- Mode and setpoint: on mini-splits, make sure it's on Cool, not Dry, Fan or Heat.
- Power: check the breaker, and don't run a window AC on an extension cord.
- Sizing: a unit too small for a sunny top-floor room will run nonstop and never catch up.
Low refrigerant means a leak, and federal rules require refrigerant work to be done by an EPA Section 608-certified technician. On an older window unit, that repair rarely makes sense.
NYC window AC rules
NYC311 says a common window AC doesn't need a permit; units over 3 tons (36,000 BTU per hour) need a DOB equipment use permit. Any unit must be installed securely, supported from underneath or fastened from inside with angles, using metal brackets or rails fastened to the building. Never level it with loose wood blocks, bricks or books, don't put anything on top of it, and fix it so the window can't be opened accidentally.
Where window guards are required (for example, apartments where a child 10 or younger lives), an AC in that window must be permanently and securely installed so there's no unguarded opening larger than 4½ inches. Window guards are the landlord's responsibility; see HPD's window guard page.
When a mini-split makes sense
- You're replacing several window units and want your windows and light back.
- You want efficient heat as well as cooling. Mini-splits are heat pumps.
- Your home has steam or hot-water heat and no ducts.
An install usually needs a dedicated electrical circuit from a licensed electrician, a spot for the outdoor unit, and in co-ops and condos, board approval. See our mini-split install guide.
Who to hire
For mini-split repair and installation, use an HVAC company with EPA 608-certified techs, plus a NYC licensed electrician for the circuit. NYC's home improvement definition includes installing central heating or air conditioning, so ask for a DCWP license on those jobs.
Questions
Do I need a permit for a window AC in NYC?
Not for a common window unit. Units over 3 tons (36,000 BTU per hour) need a DOB equipment use permit. Any unit must be installed securely with proper brackets or supports.
Can I remove a window guard to install my AC?
No. Where window guards are required, the AC must be permanently and securely installed so there's no opening larger than 4½ inches. Talk to your landlord.
Why is my window AC running but not cooling?
Often a dirty filter or coils, ice on the coils, or a unit too small for the room. A refrigerant leak is another possible cause.
Sources
Rules and phone numbers can change. Check the official source before relying on them.
Related guides
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