Houston AC Not Cooling? Check These First

In Houston, the #1 reason your AC stops cooling is a clogged condensate drain — not a refrigerant leak, not a compressor failure. The drain line backs up, the float switch trips and shuts down your system. A $10 bottle of bleach fixes it. Before you call a tech ($75–$200 diagnostic), run through these Houston-specific checks.

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Houston homeowner checking thermostat with AC not cooling

Houston-Specific Causes (In Order of Likelihood)

1. Clogged Condensate Drain

$0–$200

Houston's humidity produces 15–20 gallons of condensate daily. Algae and mold clog the PVC drain line. The float switch (safety device) shuts down your system to prevent water damage. Fix: pour 1 cup of bleach down the drain line opening near your indoor unit. If water starts flowing, problem solved. If not, the clog is deeper — a tech can clear it with compressed air or a wet-dry vac ($75–$200).

2. Frozen Evaporator Coils

$0–$450

Dirty filter + Houston humidity = ice on coils. Check for ice on the copper lines going into your air handler. If frozen: turn system to FAN ONLY for 2–3 hours to thaw. Replace the filter. Restart in COOL mode. If it freezes again, you have a refrigerant leak ($225–$1,600) or airflow restriction that needs a tech.

3. Dirty Air Filter

$5–$15

Houston's pollen, humidity and year-round AC use clog filters faster. A solid gray/black filter restricts airflow enough to shut down cooling. Replace every 30 days in summer. Every 14 days during cottonwood or pollen season.

4. Tripped Breaker

Houston thunderstorms cause power surges that trip HVAC breakers. Check your breaker panel — flip the HVAC breaker fully off, wait 30 seconds, flip back on. Check both breakers (indoor unit and outdoor unit have separate breakers).

5. Capacitor Failure

$120–$475

If the outdoor unit hums but the fan doesn't spin, it's usually a dead capacitor. Houston's heat accelerates capacitor failure. This requires a tech — capacitors store lethal voltage even when the system is off. Don't touch them.

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