Carrier Air Conditioner Not Cooling [How to Fix]

The primary reason for getting an air conditioner is to have cool air in your home. If you have the problem of a Carrier air conditioner not cooling, it is crucial to find out why and fix it.

Carrier air conditioner not cooling

Carrier Air Conditioner Not Cooling – How to Fix

There are several things that can possibly cause an air conditioner to stop cooling. Check the following parts and fix faulty ones if a Carrier air conditioner is not cooling:

1. Air Filter

The filter is usually in the indoor unit, in front of the evaporator coil. It is the first thing you see once you open the air handler. Typically, you should replace the filter every three months, according to the instructions of the manufacturer. You may want to contact Carrier to get new filters or find an authorized dealer around you. If the filter is the reusable type, you must wash it every two weeks.

If yours have never been replaced, it may be time to do that. Open the air handler and remove the filter. Check it for dirt; a significant amount of dirt on the filter explains the cause of the cooling problem. Dirt restricts airflow and affects the cooling capacity of the air conditioner. Wash the filter in warm water and soap or replace it if is the disposable type. The air conditioner should be up and running in no time.

2. Thermostat

It is crucial that you check the thermostat settings to ensure they are correct. It must be set to the Cool mode of operation and the temperature must be low enough to accommodate the operating mode. A change in the temperature setting or mode of operation affects the air conditioner’s cooling capacity.

Also, check the fan setting. The best step is to set it to Auto instead of On; if it is set to On, the fan will always run and make the air conditioner look as if it is not cooling. After these adjustments, the air conditioner should begin to run normally and cool. If that happens, you have solved the problem. Otherwise, look for other possible causes of the problem.

3. Evaporator Coil

Turn off the air conditioner and disconnect it from electric power. Open the air handler to inspect the evaporator coil. That means you have to remove the air filter. Check the ice on the evaporator coil; if it is excessive, you may have to leave the unit off until it all melts. Otherwise, turn on the air conditioner and use the air conditioner fan to melt the ice on the coil.

While it sounds odd, the evaporator coil can freeze. And if it freezes, it becomes difficult to release cold air. It is in the evaporator coil that the refrigerant flows and absorbs the heat from the air received through the intake vents. Ice acts as an insulator to prevent air from flowing out or into the coil. Therefore, the cold air remains trapped, lowers the temperature, and causes freezing.

A few reasons cause ice to accumulate on the evaporator coil. If the filter is dirty, its proximity to the coil creates a problem. The dirt insulates the evaporator coil and prevents cold air from flowing out of it into the room. Also, low refrigerant levels cause ice to form because the pressure drops. Furthermore, problems with the condensate drain can cause freezing. It is best to check these issues and fix them to prevent a recurrence of the evaporator coil problem.

4. Condenser Coil

The job of the condenser is to condense the refrigerant and release heat from the air conditioning system. That means it must be in the open and uncovered. However, its location outside the house leaves it vulnerable to dirt and debris, which can cover it and prevent heat escape.

Therefore, if a Carrier air conditioner is not cooling, inspect the condensing unit. Typically, you should clean it every three months, but it is not always a convenient chore. But that may mean that there is an accumulation of dirt, trapping heat in the system and reducing its cooling capacity. 

Open the condenser and clean the fins of its coil. Clean the fan and other parts while cleaning the coil. Carefully clean the fins because they are fragile and being forceful can bend or damage the find beyond repair. Ensure every part of the condensing unit is clean before running the air conditioner again.

5. Refrigerant

While it is not common to see a leak in the air conditioner’s sealed system, age, corrosive materials, and a lack of service can cause a leak over time. You may notice oil stains around the cooling pipes and refrigerant lines in the outside unit; those are signs of a leak. Contact the Carrier Service Center to report the issue or employ the services of a qualified professional HVAC technician for further assistance. 

Fixing a refrigerant leak is usually the job of a professional because of its complexity and the involvement of the gas. It can be dangerous to inhale large amounts of refrigerant, so it is crucial to find a permanent solution as quickly as possible.

In some cases, the cooling problem stems from the size of the air conditioner. The correct air conditioner size for your home depends on the British Thermal Units (BTUs) per square footage. In other words, it depends on the unit’s cooling capacity. Using an air conditioner smaller than the size of a room means it cannot cool it as it should. 

The lapse may not be quickly evident when the weather is moderate, but in hot weather, you will notice the unit’s lack of cooling capacity. Apart from the BTUs and square footage of the room, also check the prevalent weather in that area, the construction quality of the house, and the insulation as well. These factors inform the size and type of air conditioner to purchase.

Important Note

Ensure the air conditioner is getting enough electric power from the circuit breaker. If the air conditioner is not turning on at all, check the breaker outside the house. It may have tripped, especially if there was a recent power outage. Turn it on and check the unit. If the problem persists, the breaker may have damaged fuses; they will need replacements.

But if the circuit breaker is intact, you may want to test the wall outlet and power cord. This is especially necessary if the problem persists. The power cord may be faulty or the wall outlet, if it applies, may not be providing enough voltage to power the unit. If that is the case, use the services of an electrician to replace the wall outlet or buy a new power cord for the unit. Ensure the air conditioner has a dedicated breaker and outlet because of power needs.

In addition, you may want to check the compressor. A malfunctioning one can cause the air conditioner not to produce cold air. Sometimes, it produces cold air but not enough of it. However, compressors hardly fail, so it is important to run a careful test on the one in your unit before determining whether or not you should replace it.

Check out these other articles…

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Carrier Air Conditioner Compressor [Problems Solved]

Carrier Air Conditioner Modes [Detailed Guide]

Carrier Air Conditioner Fan [Issues & Solutions]


A Carrier air conditioner not cooling is a serious problem that needs immediate attention. Most times, the cause of the problem is something as minor as a dirty filter; cleaning or replacing it fixes the problem. The same is true if the evaporator coil is frozen or the thermostat is improperly set.

However, if the problem is from a leak in the closed system, you will need professional help to fix it. The same applies if the compressor is the problem. Try getting a qualified technician to service the unit and ensure you carry out regular maintenance checks to prevent possible problems in the future.

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