handymanDIY Friendly

build

Why is my AC unit running but not cooling the house?

If your AC runs constantly but the house stays warm, the most likely cause is a frozen evaporator coil or a dirty condenser.

Category:HVAC

Difficulty:Moderate

Time:45 min

Success:50%

Updated:Jun 9, 2026

quick_referenceQuick Answer

For Why is my AC unit running but not cooling the house?, start with "Check and replace the air filter": Locate the return air filter and hold it up to light. If it's dirty, replace it with a new filter of the same size and MERV rating. Stop DIY if you see ice on the outdoor unit. This is listed as a moderate recovery and usually takes about 45 min.

verifiedGuide Snapshot

Repair areaHVAC

Estimated time45 min

DifficultyModerate

Stop conditions3

Last updated Jun 9, 2026. Review the stop conditions before continuing.

account_treeRecovery State

DeviceAc Unit

Current stateInsufficient Cooling

Specific stateRunning Constantly

Failed stepFrozen Evaporator Coil

Likely failure typeBlocked Path

DIY boundaryDIY recovery first

paymentsCost decision

help1. Understand the Problem

An AC that runs without cooling typically has a refrigerant issue or an airflow problem. A dirty air filter or blocked condenser coils can cause the evaporator coil to freeze. Low refrigerant levels also prevent proper heat exchange.

build_circle2. Try This First

Best First Step

Check and replace the air filter

Locate the return air filter and hold it up to light. If it's dirty, replace it with a new filter of the same size and MERV rating.

visibility3. Visual Guidance

See what's happening and how to try the first recovery step.

Inspect the evaporator coilRemove the access panel on the indoor air handler. Look for ice buildup on the copper coil. If frozen, turn off the AC and run the fan only.

Clean the condenser coilsTurn off power to the outdoor unit. Use a coil cleaner spray and a garden hose to remove dirt from the fins.

Check the condensate drain lineLocate the PVC drain line near the indoor unit. Pour a cup of vinegar through the T-vent to clear algae buildup.

Monitor the systemAfter cleaning, turn the AC back on. Wait 15 minutes and feel the air vent temperature. It should be 15-20°F cooler than room air.

autorenew4. If That Doesn't Work

Try the next recovery options.

Clean the outdoor condenserTurn off power, remove debris, and spray the condenser fins with a garden hose from the inside out.

chevron_right

Call an HVAC technicianIf the system is low on refrigerant, a professional must locate and repair the leak before recharging.

chevron_right

Frequently Asked Questions

expand_more

warning5. Stop DIY If

Don't continue if any of these apply.

reportYou see ice on the outdoor unit

reportThe compressor makes a clicking sound and shuts off

reportYou detect a burning smell from the air handler

Still stuck?Get personalized help with AI Recovery.

Same Device Recovery States

Device index arrow_forward

build

AC Warm Air FixIf your air conditioner blows warm air, a dirty condenser coil, low refrigerant, or a faulty capacitor is likely the cause. Diagnose step by step.

build

AC Not CoolingAn AC that runs but blows warm air can be due to a dirty condenser coil, low refrigerant, or a frozen evaporator. Here's how to troubleshoot.

build

AC Coil CleaningBoost your AC's cooling power by cleaning dirty condenser coils. No tools needed—just a hose and a few minutes.

build

AC Blowing Warm Air After Filter ChangeWarm air after a filter change often means the filter is installed backwards, the condenser unit is dirty, or the thermostat is set wrong.

build

AC Leaking Water InsideAn indoor AC unit leaking water usually means a clogged condensate drain line or a frozen evaporator coil. Clearing the blockage stops the leak.

water_drop

AC leaking insideWater dripping from your indoor AC unit is usually a clogged condensate drain line. Clear it in 15 minutes with a wet/dry vac before the water damages your ceiling or floor.

Similar Failure Pattern

Slow kitchen sink drain Dryer not drying AC Warm Air Fix Sink draining slowly

This page provides general DIY guidance.
If you're unsure, it's always best to consult a professional.