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air conditioner is running but not cooling the house

If you’re wondering why your air conditioner is running but not cooling the house, there are a few potential reasons. It’s no fun when you’re trying to stay cool during a heatwave, and your HVAC system is just blowing hot air. If you want to troubleshoot the problem before calling your local HVAC specialist, here are the most typical reasons and what you can do to fix it.

AC Resource: What Causes an Air Conditioner to Turn On and Off?

Incorrectly Set Thermostat

If your home is becoming a bit hotter than usual, check the thermostat settings first. It’s not uncommon for someone to accidentally bump the thermostat settings, causing the air conditioner to turn off or blow less cool air.

If the thermostat is set correctly, but your home is still too warm, there may be an issue with the thermostat itself. If it’s a manual thermostat, ensure that the mercury switch is not stuck. If it’s an electronic thermostat, you may need to change the batteries.

Clogged Air Filter

When your air conditioner has been running for a while without cooling the house, it may be because the air filter is dirty. A dirty air filter prevents cool air from flowing through the system and can cause the evaporator coil to freeze.

To clean or replace the air filter, first turn off the power to the unit at the breaker box. Remove the front panel of the air conditioner and locate the filter. Most filters can be pulled out and cleaned with soap and water. If it’s excessively dirty or damaged, you’ll need to replace it.

Changing your AC filter is an important part of maintaining your air conditioner.

Low Refrigerant

A refrigerant leak is one of the most common reasons air conditioners stop cooling. When the refrigerant level is low, it prevents the evaporator coil from getting cold enough to cool the air properly.

When this happens, your air conditioner will run continuously. It’ll keep trying to chill your house, but it won’t do without enough refrigerant. Since handling refrigerant is risky, have your local HVAC specialist evaluate your system.

Dirty Evaporator Coil

If the evaporator coil becomes dirty, it can’t absorb heat as effectively. Over time, the dirt and grime build-up can cause the coil to freeze, which will prevent the air conditioner from blowing cool air.

To clean the evaporator coil, you’ll need to turn off the power to the unit and remove the front panel. Use a soft brush to remove any dirt and debris gently. You can also use a vacuum with a soft attachment to suck up any dirt. Once you’re finished, replace the front panel and turn on the power.

Frozen Air Conditioner

If you’ve changed the filter but still don’t get cool air, go inside your ac unit. Your air conditioner is freezing up outside if you see ice or dampness. There are many reasons why this may occur.

Before calling a professional, try turning off the ac unit and melting the ice. To speed up the procedure, switch on simply the fan on the air conditioner or use a hairdryer. Restart the air conditioner after the ice has evaporated.

Your air conditioner is your friend.

Leak in Refrigerant Line

When your air conditioner is leaking refrigerant, it’s likely because there’s a hole or crack somewhere in the line. It needs repair as soon as possible since leaky refrigerant can cause damage to your unit.

Call an HVAC specialist right away if you see any signs of a refrigerant leak. Do not attempt to repair the leak yourself.


During the hot weather, the last thing you want is for your air conditioner to stop working. The things mentioned above are the most common reasons your air conditioner is running but not cooling the house. By troubleshooting the problem, you may be able to fix it without calling a professional. However, if you’re still having issues, it’s best to contact your local HVAC specialist for assistance.

If you need air conditioner repair, contact Furnace Repair Winnipeg today! We offer a wide range of HVAC services to keep your home comfortable.

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