Ac Won’t Stop Running

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Reasons Why Window Air Conditioner Keeps Running When Turned Off

What To Do When Your AC Won’t Stop Running

There are three problems with window air conditioners which irritate their users the most. The most frustrating among them especially because it weighs heavily on your electricity bill is when the window air conditioner keeps running when turned off.

You have switched it off from the remote, turned its thermostat to the extreme left and even smashed your hand against its control panel. Still, as if to test the limits of your patience, the air conditioner keeps on churning out cool air. That too when your room temperature has already become comfortable.

Want to get rid of this problem? Then keep on reading.

Find The Fan Capacitor

After the service panel is removed, find the fan capacitor. Most capacitors are cylindrically-shaped, like a large battery. There will also be a few wires connected to the top of the capacitor.

Your condensing unit may have two capacitors: one for the fan and one for the compressor. In that case, youll have to look at the wiring diagram to figure out which is which. The fan capacitor may also be labeled.

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:

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Blocked Vents Are Reducing Air Flow

Blocked supply vents are another reason your AC unit isnt putting out enough cold air. Check your vents to make sure there isnt dirt or dust build-up that could be preventing airflow. Toys, furniture, or closed dampers may also be the problem. Rearrange furniture away from registers and check for obstructions that may have fallen into your ducts by accident.

Faulty Fan Limit Switch

Air Conditioner Won

Even when the correct fan settings are selected, the fan motor may continue running even when the air conditioner isnt cycling. This can happen if the fan limit switch is stuck in the override position. Resetting the limit switch located near the blower fan will stop the fan from blowing unless directed by the thermostat.

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Air Conditioner Is Turned Off But Fan Keeps Running

If your blower fan is continuing to run after the system has already turned off, and you made sure your thermostat isnt set to the on position, then youll want to try and pinpoint the issue. Listed below are the three most common reasons why the blower fan continues to run after the system has already turned off.

  • If its extremely hot outside, your blower fan may continue to run. Why? The system just cant get to the temperature that you set the thermostat to. This is a common problem for homes with an undersized cooling system. In this situation, you can either invest in a bigger and more powerful cooling system, or you can wait until the weather gets cooler. Either way, make sure you perform regular maintenance on your air conditioning system. Failure to properly clean and maintain your air conditioning system can cause it to work harder than it needs to.
  • A damaged thermostat may also be the issue. If you notice your air conditioner and the blower fan all of a sudden start running, then the problem is more than likely the thermostat. This is fairly inexpensive to fix and installing a new one isnt that difficult either.
  • Thermostat Function Settings & Fan Settings

    If your AC is equipped with toggle or slide switches, you most likely see two of them. One labeled Cool, Off, Heat and the other Auto, On. In some cases, you may also see a third setting Recirculate. Note, on touchscreen thermostats you will usually see the same settings on the home screen or by pushing the Fan button. First, lets look at what each of these settings mean, then well cover the purpose of the separate fan switch.

    Mode Settings

    • COOL Automatically turns on and off your entire AC system when the temperature rises above your desired setpoint.
    • OFF Neither your AC nor Heater will turn on no matter what the temperature is on the thermostat.
    • HEAT Automatically turns on and off your entire heating system when the temperature falls below your desired setpoint.

    Fan Settings

    • Auto automatically turns on and off your indoor fan simultaneously when your AC or Heater turns on or off. Note, a few minutes delay before the indoor fan turns on after the compressor or furnace turns on is normal. Likewise, the indoor fan motor running a few minutes after the compressor or furnace shuts off is also normal.
    • On keeps the indoor fan running 24/7 both when the AC or Heater is running and after the AC or heater shut off. Remember, if this switch is set to on, its not that your AC wont shut off your fan wont.
    • Recirculate depending on the system and how its programmed, recirculate will intermittently run the indoor fan to circulate room air.

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    Air Conditioner Wont Blow Cold Air

    If your AC system turns on but doesnt blow out cold air, ensure all the vents are open and the thermostat is set properly. If these arent the problem, check the air filter. If its clogged with dirt or other debris, you wont get any air flow. Since the clog may cause the evaporator coils to freeze, the ice and frost will clog the air flow even more. If thats the problem, clean the filter with a soft brush, mild soap, and water. Clean and change your filter often to avoid that problem in the future. You may also have a problem with the fan or fan motor. If the fan turns easily, you may have a problem getting electrical power to the motor or a leak in the refrigerant line. In these cases, youll probably require a qualified HVAC technician to come inspect the unit.

    Adjust Thermostat Fan Settings

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    Make sure the air conditioner is actually running and its not simply the fan running alone, making it appear as though a cooling cycle is constantly going. Check the fan settings on your thermostat the toggle should be in the AUTO position so that the fan only runs while the air conditioner is on. If the thermostat fan setting is ON, move it to AUTO with the temperature set above the current room temperature, the thermostat should tell the air conditioner to shut off as well as the fan.

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    Your Air Filter Is Dirty

    A dirty air filter can impede the flow of air and can cause a host of problems. Short cycling is when your air conditioner turns on and off again in very short bursts without completing a full cooling cycle. When filters are blocked your AC unit has to work harder, creating higher energy bills and unevenly cooling your home. It may even cause your air conditioning system to stop working. Regularly cleaning or changing your air filter will help you avoid a future problem or you can save money and stress with routine maintenance.

    Your Ac Unit Is Old And Needs To Be Replaced

    Every HVAC unit wears out eventually, no matter the brand or how well you maintain it. So if your AC is more than 20 years old and constantly runs or doesnt cool the way it once did, you should consider replacing it with a new energy-efficient model.

    Replacing your old unit will save you money on energy bills in the long run. Plus, the relief of having a unit that cools your house to the temperature you want could mean its better to replace your AC unit. Newer, higher efficiency systems need about half the electricity of an older unit.

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    Extreme Heat And Humidity

    We are all familiar with extreme temperature in Phoenix, so a constantly running air conditioner tends to be the norm. You should expect your AC to run more than normal on hot and humid days. If youre new to Phoenix, dont let this alarm you. If the air conditioner doesnt go back to regular cooling cycles when it gets cooler, thats when you should think about calling for professional service.

    If high humidity is a problem in your home, talk to your technician about installing a whole-home humidification system.

    Check Your Air Filter For Immediate Relief

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    When was the last time you changed your air filter?

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    If it’s been awhile, it’s probably dirty restricting air flow. This will cut down on the amount of cool air your air conditioner can produce, which in turn will make your A/C seem to run more through the day. When your air filter is clogged, your air handler must work harder to compensate.

    Would you believe the most common reason a HVAC breaks down is due to a dirty filter?

    A dirty filter makes your system work harder causing it to overheat. Cleaning the debris that builds up on your filters will aid with the flow of air. Clean or replace your filters once a month or as recommended by the manufacturer.

    Without enough air flowing over the coils, the system cant remove humidity and cool the air to the set temperature, so it keeps running when it shouldnt.

    This brings us to another possibility…

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    Problem With The Temperature Sensor

    As stated earlier, all window air conditioners come with a temperature sensor . This device is mounted on the room-facing side of the evaporator, though you cant see it since its hidden inside the front-facing casing of the air conditioner.

    The main purpose of the sensor, as its name implies, is to measure your room temperature. It then uses that measurement to tell the compressor whether to keep running or to shut down .

    Unfortunately, we have seen some window air conditioners whose temperature sensor went awry. It is no longer able to measure your room temperature and the compressor, which relies on the sensor to turn on/off, keeps on churning out cold air.

    To test the sensor, you need two things: technical specs of the thermistor of your window air conditioner and a multi-meter. Once you have them, inspect the control board. It may happen that the sensor is working fine, but only its connection with the control board has become loose.

    Check The Motor Overload Reset Switch

    Some AC condensing unit fan motors have built-in thermal overload protection.

    Whats thermal overload protection used for?

    Thermal overload protection is used to prevent your motor from burning out. When an electric motor has an issue, it usually will overheat.

    When the fan motor overheats, the thermal overload switch will trip. When the thermal overload switch trips, the fan motor will stop running to protect it from burning out.

    Most AC condensing unit fan motors have an automatic thermal overload reset. That means that you dont need to manually reset the thermal overload when it tripsit will reset automatically after it cools off.

    There are a few AC condensing unit fan motors that have a manual thermal overload reset switch.

    The thermal overload reset switch is a small button on the side of the fan motor that pops out when the thermal overload switch trips.

    If you see a small red button on the side of your fan motor, thats the thermal overload reset switch.

    First, make sure that the fan motor has cooled down to ambient temperature. Next, press the thermal overload reset button.

    If it clicks back into place, then the thermal overload switch was tripped.

    If the button doesnt click back into place then the motor is still too hot, or there is another failure somewhere inside the fan motor.

    The next task is figuring out why the thermal overload tripped in the first place.

    It could be due to one of the following issues:

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    The Full Replacement Solution

    If the AC is a recent installation, one of the possibilities is that the air conditioner was incorrectly sized when installed so that its not powerful enough to cool the space. The AC will stay on to attempt to lower the temperature enough, but wont ever make it. Unfortunately, the only way to remedy this is to replace the unit. Make sure you always work with licensed professionals who will carefully size the unit so this problem doesnt happen again.

    If your AC is more than 15 years old, constantly running often means its worn down and needs to be replaced. Speak to an HVAC technician for a professional opinion and diagnostic.

    Is It Normal For My Air Conditioner To Run All Day

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    The truth is, it can be perfectly normal. For example, the temperature in your home may constantly be rising above what youve set on the thermostat for any number of reasons. Its worth checking if your air conditioner is properly sized and functioning well, too. If youre unable to find an issue yourself, consider contacting an HVAC professional.

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    Damaged Or Loose Thermostat Wiring

    How did things look when you had the thermostat off the wall and checked the yellow wire? Were any other wires loose?

    Is any of the wiring thats attached to your thermostat damaged? Or perhaps they are just old. Overtime, the sheath of insulation that goes around the wires deteriorates, and this will ultimately expose the wire itself.

    If exposed wires touch each other and maintain a constant connection, this could keep your condenser runningmeaning your air conditioner wont turn off.

    There are several things that can cause wire damage, but here are the most common:

    • Accidentally putting a nail in the wall where wires are located
    • Rodents in the walls chewing on your wires
    • Outside wires can be hit by a weed whacker
    • Faulty wiring, direct from the manufacturer

    Its easy to inspect for damage to your thermostat wiring. Simply take the thermostat cover off the wall by removing the screws that hold it there.Then you can do a visual inspection.

    When it comes to electrical wiring, there are several warning signs you can look for.

    Your outdoor wiring will be protected within a conduit housing. If you see damage to the housing, in all probability there may be damage to the wiring within as well.

    Solution.If youve already ruled out a defective thermostat, and youre sure the issue is with your thermostats wiring, youre going to have to hire an electrician or an HVAC technician.

    You call also follow this walkthrough.

    What If Your Ac Wont Stop Running

    Obviously, when your air conditioner wont turn on, this is a problem that needs to be dealt with right away. What if you turn on your air conditioner though, and it doesnt stop running? This may not seem like a serious issue when its as hot as it is in Florida, however this could poorly impact your air conditioner more than you might realize.

    If your air conditioner continues to run, it will cause wear and tear to happen more quickly. So if you notice that your air conditioners fan or compressor is running continuously without cycling off as usual, then you may have one of the following problems.

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    Inspect The Fan Limit Switch

    The fan of your air conditioning unit turns on when instructed by the thermostat. But it can also do so as part of an independent air circulation process. This is made possible by the presence of a fan limit switch. The fan limit switch overrides any thermostat signal telling it to stop running so that it can keep going. If your air conditioner doesnt turn off, check whether you need to switch the fan limit switch from manual to automatic.

    Blame The Thermostat Again

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    Here I go blaming the thermostat again! Well, not really in the beginning of the article I blamed the thermostat user not the thermostat itself. However, a faulty thermostat can in fact be the reason an AC wont shut off. A faulty thermostat can cause the indoor unit, outdoor unit or both to keep running and not turn off. In my experience, the thermostat being the culprit is far less likely than other scenarios weve discussed. So, before you run to Lowes for a new thermostat and waste your money, call a pro and get a proper diagnosis.

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    Is It Okay To Leave Ac Fan Running

    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.

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