How to Clean an AC Unit — Seasonal Guide

Credentials

• Licensed HVAC contractor
• Fully insured crews
• EPA Section 608 certified
• NYC DOB registered

Certification and license records are available on request while our public verification page is in progress.

• Set the thermostat to off and switch off the breaker for both the indoor and outdoor units.
• Lay old towels around the air handler in case water spills from the drain pan.
• Buy a matching filter size and coil cleaner before you open anything.
• On co-op buildings, check whether roof access requires a super to escort you.

Remove the return-air filter and check the arrow: it must point toward the air handler. A pleated filter with a visible layer of dust across the surface should be replaced, not cleaned. Washable filters are the exception; they get rinsed, air-dried and refitted only when fully dry. A partially blocked filter is the single largest cause of low cooling capacity in NYC apartments.

Follow the coil-cleaning steps in our dedicated coil-cleaning guide: vacuum, apply a coil-rated foaming cleaner, rinse gently, straighten fins with a fin comb. Coil cleaning is where the biggest capacity gain is; skipping it undoes most of the rest.

With the panel off, vacuum the blower wheel from outside the housing. Only pull the wheel for a full clean if you are comfortable disconnecting the motor and reassembling it — a poorly aligned blower wheel throws the whole air handler out of balance. Wipe the cabinet interior; check the insulation for damp spots that suggest a slow leak on the coil above.

Clear leaves from the base grille, straighten any bent fins with a fin comb, apply condenser-rated cleaner and rinse gently. Check that the pad is level; a sagging pad tilts the compressor and shortens its life. Confirm the disconnect box and whip are dry and secure before restoring power.