Carrier AC Fan Won’t Shut Off—What’s Wrong?

It's normal for a Carrier air conditioner (AC) fan to run for a few minutes after turning the power off. However, if the fan runs continuously without stopping, it could indicate a serious technical problem. To help you trace why your AC fan won't shut off, we consolidated some of the best diagnoses from AC experts.

Does your AC fan keep running even after you have turned the unit off? When your Carrier AC fan doesn't shut off, it could be one of the following reasons:

  • A faulty thermostat or incorrect setting
  • The relays are stuck
  • A faulty electrical wiring

A standard AC unit has two main fans. You need to identify which fan is not working to make a correct diagnosis. As you read on, you'll learn more about the fans inside your AC, the possible reasons why it's not shutting off, and what you can do to resolve the problem.

A big Carrier air conditioning unit mounted on reinforced metal brackets, Carrier AC Fan Won't Shut Off—What's Wrong?

Air Conditioner Fans

There are two main fans inside a standard air conditioner—one that blows air indoors and one blowing air outwards. Both fans are essential to maintain the temperature balance within the AC unit and ensure optimum performance.

A big Carrier air conditioning unit mounted on reinforced metal brackets, Carrier AC Fan Won't Shut Off—What's Wrong?

Indoor/Blower Fan

The indoor fan or 'blower' fan is what blows cold air into the room. It draws air into the evaporator coils to generate cold air, then blows it indoors. You can find it inside the AC unit near the condenser coils, and it's not always visible unless you open the AC unit.

An air conditioning unit mounted on AC brackets

Outdoor/Condenser Fan

The outdoor fan or 'condenser' fan is usually located in the outer part of the unit. It draws hot air from the cooling coils and brings it out to prevent the unit from overheating. A properly working condenser fan is the key to an efficient and long-lasting AC system.

A focused photo of a mini split unit

Running AC fans every once in a while can help filter the air inside a room. However, it is not advisable to keep it frequently running because it can wear down the motor faster. AC fans also need regular cleaning and maintenance to ensure the entire system functions properly.

If you're experiencing the opposite and your AC keeps shutting off, you might want to check out this article: "Air Conditioner Turns On and Off Repeatedly."

Reasons Why The AC Fan Won't Turn Off

In most AC units, when you first turn it on, it will initially go to 'FAN' mode, and the blower fan will run for a few minutes before switching to cool mode when you begin to feel the cold air.

The blower fan should only start running when you turn the unit on and should stop as you turn the AC off.

If the fan continues to run when the rest of the system is off, here are the possible reasons:

Faulty Thermostat Or Incorrect Settings

If an AC unit has a malfunctioning thermostat, it may not be able to detect if it has already reached the desired temperature setting. As a result, the fan or the entire AC system runs continuously to comply with the set temperature.

Reasons that a thermostat may be broken include a wiring defect, broken relay, or a problem with the control board. The thermostat may require replacement, or an electrician may need to check the wiring.

What To Do

Check the thermostat settings and make sure the fan is not set to 'ON.' If the thermostat has an 'OFF' or 'AUTO' setting, switch to this setting first and check to see if the fan turns off. If the problem persists, consult an AC repair expert to diagnose the issue further.

Carrier suggests using a Wi-Fi thermostat for energy efficiency and higher savings.

Check out this Honeywell programmable Wi-Fi thermostat on Amazon!

Stuck Relays

Air conditioners have high-voltage switching mechanisms called relays that safely control the flow of electricity inside an air conditioner when switching the unit on and off.

Two things can happen to relays. It's either they are damaged, or they are stuck. If there is damage in the relay, it won't provide power. If it's stuck, it either won't provide power or will continuously transmit power, and the AC won't turn off.

Relays have natural wear and tear and can sometimes get stuck, keeping the circuits closed. Stuck relays can lead to a continuous electricity supply and cause the AC fan to run constantly.

What To Do

Relays are usually found at the back of an AC unit. Gently knock the relays a few times to move the wires. Clean any dirt and debris that may be stuck in the relays. If this does not resolve the problem, it may be time to call an AC expert to replace the relays.

Check out this Carrier HVAC Replacement Relay on Amazon!

Electrical Problems

An AC unit has a number of electrical components that cause the AC fan to run continuously. It could be a stuck relay switch, a fault in the compressor contactor fuse, or a stuck fan limit switch.

When the problem is a stuck switch, the solution is often cleaning or replacement. Certain AC components can deteriorate over time, especially with frequent use.

What To Do

If you're not an experienced electrician, this problem is best left in the hands of an AC repair expert. However, there are a few simple things you can do initially, such as resetting the AC unit. This often resolves any minor internal system problem.

How To Reset An AC Unit

A carrier air conditioning unit mounted on reinforced brackets

When a Carrier AC unit is not responding to inputs, resetting its internal computers can restore its default settings and normal functions. Instructions may vary depending on the AC unit, but here's a general overview of the reset procedures:

  1. Find the AC unit's control panel and look for the reset button.
  2. Press and hold the button for at least 3 to 5 seconds.
  3. Wait until a light flashes on the display to confirm the reset.
  4. Wait for at least 30 minutes and let the internal system restore.

System restore usually resolves minor problems with the thermostat, electrical wiring, and a tripped breaker. When an AC unit starts malfunctioning after a power outage, sometimes a system reset is the easiest solution.

Can an AC reset fix an AC fan that won't shut off? Although it's not guaranteed, there is a good chance that it can fix a system malfunction that's causing the fans to run continuously, unless it is a problem with the components.

Here's another article you can check out for further information about resetting an AC: "How To Reset Lennox Air Conditioner."

Is It Okay To Leave AC Fan Running?

An up closed photo of a Carrier air conditioning unit

Some leave the AC fan running to help circulate and filter the air, especially in compact rooms with limited ventilation. However, there are some concerns regarding energy efficiency and whether it can cause damage to the AC unit long-term.

If you are using an old AC model, it is recommended to not always keep the fan running or to switch the system on and off frequently. This can cause damage to the components and accelerate the system's lifespan.

Newer AC models have an 'AUTO' setting that allows the unit to adjust its setting automatically and adjust to the indoor temperature. The fan will only run when the AC system is turned on.

Does AC Fan Use a Lot Of Electricity?

A Carrier Ac mounted on a reinforced bracket for a small store

You're probably wondering whether an AC fan has the same energy consumption as when the unit is on cool mode. Using the AC fan is a lot cheaper because it uses less power and does not require the compressor to run. Setting it on 'AUTO' mode will make it more cost-efficient.

A lot of new AC models have energy-efficiency features. Turning on the AC fan consumes around 75 to 150 watts, while an air conditioner on cool mode consumes around 1000 watts. The consumption also depends on whether the fan is running on a low or high setting.

In Closing

A big Carrier air conditioning unit mounted on reinforced metal brackets

An AC fan that won't shut off is not typically a problem that you DIY because there are numerous technical reasons behind it. An AC specialist can best diagnose the problem and advise if any component needs replacement.

We hope you learned a few things about how your AC fan works and why it's important to keep it running properly. You can learn more about how to maximize your AC usage through these links:

Is It Cheaper To Leave Air Conditioner On All Day?

How Long Can You Run A Portable Air Conditioner Continuously?

What Temperature Should A Portable Air Conditioner Be Set At?

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