Bravo Mechanical LLC — Licensed & insured HVAC contractor (License #8822) · 1 Fowler Avenue, Yonkers, NY 10701 · Serving all of Westchester County · (914) 361-9142 · 24/7 emergency service · Request a free written estimate

Why Is My AC Not Cooling? — Westchester Homeowner Diagnostic Guide

9 reasons your AC is running but not cooling, what you can fix yourself in 10 minutes, and which problems need a Westchester HVAC tech today.

Published 2025-12-03 · Bravo Mechanical, Westchester County, NY

Quick answer: The 9 most common reasons a central AC runs but doesn't cool a Westchester home are: (1) clogged filter, (2) frozen evaporator coil, (3) dirty outdoor condenser, (4) low refrigerant from a leak, (5) failing capacitor, (6) failing contactor, (7) failed compressor, (8) wrong thermostat setting, (9) closed/blocked supply registers. Items 1, 8, and 9 are DIY fixes; the rest need a tech.

Step 1: 5-minute homeowner check

Before calling, do this:

1. Thermostat — set to COOL, temp 5°F below current room temp, fan on AUTO 2. Filter — pull it out. If it's gray or clogged, replace it 3. Indoor coil (above the furnace) — if you see ice, shut the system off immediately 4. Outdoor condenser — running? Coil clean? 3 ft clear all around? 5. Supply registers — open in every room, not blocked by furniture or rugs 6. Breakers — both indoor and outdoor disconnect

If steps 1, 2, 5, 6 don't fix it, call us.

The 9 causes in detail

Symptom Likely cause DIY? Repair cost
--- --- --- ---
Warm air, dirty filter Clogged filter Yes $0
Ice on indoor coil Frozen evap coil No (shut off, call) $250–$450
Outdoor unit hot, weak airflow Dirty condenser coil No $180–$320
Warm air, hissing Refrigerant leak No $400–$1,800
Outdoor unit hums but doesn't start Bad capacitor No $180–$320
Outdoor unit silent, breaker tripped Bad contactor No $220–$385
Outdoor unit silent, no power signs Failed compressor No $1,800–$3,500
Thermostat blank Bad batteries / wiring Sometimes $0–$285
Cool in some rooms, warm in others Duct issue / blocked registers Maybe $0–$1,200

The frozen coil emergency

If you see ice on the copper coil above your furnace or on the refrigerant line at the outdoor unit:

1. Shut the system OFF (don't run cool, don't run heat) 2. Set thermostat fan to ON for 1–2 hours to thaw 3. Check filter — replace if dirty 4. Don't restart cooling until a tech confirms the cause

Common causes: dirty filter, low refrigerant (leak), failing blower motor.

Westchester-specific causes

  • Pollen-clogged outdoor coil (April–June) — wash with garden hose monthly
  • Salt-air corroded fins (Sound Shore) — coil cleaning extends life
  • Squirrel-damaged refrigerant line insulation — common in Rivertowns and northern Westchester
  • Undersized old systems in expanded Yonkers/Mount Vernon homes — never were sized for the addition

When to call us today vs. tomorrow

Call today if: ice anywhere, breaker keeps tripping, indoor temp 80°F+, anyone in the home is medically vulnerable.

Tomorrow is fine if: unit just runs longer than usual but house still cools, mild discomfort only.

Bravo Mechanical does same-day AC diagnostics across Westchester County. Diagnostic fee $185–$285, waived with repair.

Schedule an AC diagnostic → or call (914) 361-9142.

Request service or a free written estimate or call (914) 361-9142. Serving all of Westchester County, NY.