Common problems associated with air conditioning systems and AC Parts to repair them

You know how good it feels to have cool and fresh air on a hot day. That means you know how frustrating it is when the air conditioning decides not to work properly by not cooling anymore or worse still, you find that it starts leaking. It was working perfectly so what went wrong and why does it keep making that annoying noise?

Replacing your air conditioning system takes a lot of time and money and fixing the broken part is easier. You should read this article to know the possible cause of your air conditioning malfunctioning. You could only be needing to replace a faulty part that is cheap compared to buying the whole thing again and tossing yours in the trash.

If you know the problem with your air conditioning, you can go directly to it using the table of contents. However, click on your brand for specific brand parts that you need to get it working again.

How to find a local repairer in your area

If you need help and would prefer having a maintenance man service or replace your air conditioning for you, go here to find an air conditioning service man in your local area.

Disclaimer: Before you begin any repair project, or buy small engine parts for your appliance, always refer to your manufacturer’s manual so as not to void your warranty

How to use this article

The air conditioning article is organized in a way that you see the most probable cause of the problem first and the least likely culprits at the bottom. If you like to fix your appliances, look at the problem and causes listed to accurately diagnose and fix your air conditioning and have it up and running again.

Air conditioner does not cool

You bought your air conditioning so it can cool the air in the room but it is not doing that. Here are the common causes for the air conditioner not cooling.

  1. Air conditioner Air filter

For the air conditioner to cool the air properly, the air filter needs to be clear to allow free flow of air. Clogged air filters also make the evaporation coils frost over reducing the cooling capabilities.

Clean the air filter to remove any particles and replace it if cleaning is not possible.

  1. Air conditioner dirty condenser coils

As the refrigerant passes through the coils, they remove the heat from the air. If the condenser coils are dirty, the air conditioner will work harder to cool the air since the coils are not working efficiently with the buildup of debris in them. The air conditioner will keep running to maintain proper room temperature, and this might put a strain on other parts.

Inspect the condenser coils for any debris and clean them if they are dirty.

  1. Central ac unit central Compressor

First, check all other common faulty parts and establish if they are working. You should pay attention to the compressor capacitor and overload protector. The central ac unit compressor should be replaced only by a licensed technician if it is defective.

  1. Central air conditioner thermostat

The air temperature is monitored by the air conditioner thermostat, and if the temperature goes above a certain point, a switch is activated and power is provided to the compressor and fan. The air conditioner will not cool if the thermostat malfunctions in any way.

Test the thermostat using a multimeter for continuity and replace it if there is none.

Some thermostats might control a heater and will have three terminals. You need to refer to the wiring diagram to get more information.

  1. Central ac unit Thermistor

The thermistor detects the air temperature since it is a sensor. The air temperature changes the resistance value of the thermistor. The hotter it is, the lower the resistance value will be. Test the thermistor for continuity using a multimeter.

Replace the thermistor if:

  • There is no continuity.
  • The resistance value of the air conditioner does not change with the temperature.

Check the manual for specific resistance and temperature values.

  1. Air conditioner unit control board

Voltage to the compressor and fan motor is regulated by the control board. The control board regulates voltage to most of the air conditioner parts and is often misdiagnosed. Before you decide to have it replaced, ensure that all other parts are fully functional. Once you establish that they are all working, have the control board replaced.

  1. Air conditioner temperature control thermostat

If the air temperature goes under a certain point, the temperature control thermostat senses it and powers the compressor and fan. Air will continuously cool or refuse to cool at all if the thermostat malfunctions. Use a multimeter to test the thermostat for continuity and confirm if it controls a heater. Have the thermostat replaced if you find no continuity.

  1. Central ac unit temperature control board

The fan motor and compressor will only get power if the temperature control board is working properly. Check all other parts of the air conditioner before having the temperature control board replaced. Only replace it if all other parts are fully functional.

  1. Central air conditioner run capacitor

The compressor has electrical leads that connect it to the run capacitor, and the compressor will not run if the run capacitor burns out. Test it for continuity and have it replaced if there is none.

If the air conditioner fan is not working

There are times you might find that the air conditioner fan is not working. Here are some of the possible reasons that could be happening.

  1. Air conditioner dual shaft fan motor/circulator fan motor

There are two fan blades on either side of the motor. One fan draws air over the condensing coil to reduce the heat while the other directs air over the evaporator coil. Over time, the bearings can loosen and bind. You can find out if this has happened by wiggling the motor shaft and replacing it if it refuses to turn or it is loose.

  1. Central ac unit fan motor

The fan motor should be replaced if the motor bearings are loose. They are loose if the blade does not turn freely when you turn it manually.

You should also test the fan motor if it is getting power. Replace it if the motor will not run despite having a stable power supply.

  1. HVAC system relay board

Most components of the air conditioner get their voltage from the relay board, and if it is not working, the fan will not run. Ensure all other parts are working especially the fan motor capacitor and fan motor. Once you establish that they are all functional and the fan does not run, replace the relay board.

  1. Air conditioner temperature control thermostat

The electrical contacts of the temperature control thermostat burn out over time making the thermostat not work properly. When the compressor is on, the fan motor should always be running, and if it is not running, the fan motor capacitor or fan motor could be the problem.

Use a multimeter to test the temperature control thermostat for continuity and replace it if there is none.

Also, refer to the wiring diagram to find out if the thermostat controls a heater since it will have three terminals that will also need to be checked.

  1. Central air conditioner thermostat

The fan and compressor get power when the thermostat activates a switch once it senses that the temperatures have gone above a certain point. If it doesn’t work, the fan will not work. Find out if it is working by testing for continuity when the air conditioner is set to cool.

Have the thermostat replaced if there is no continuity. Also, confirm if the thermostat controls a heater from the wiring diagram.

  1. Air conditioner main control board

Most components get their voltage from the main control board, and if it malfunctions, it will stop supplying power to the fan motor. Since they can be misdiagnosed, first check all other parts if they are working. If they are in working condition, you can replace the main control board.

  1. Central ac unit thermistor

Thermistors are sensors that detect temperature in the air and will prevent the fan from running if they malfunction. Use a multimeter to find out if the thermistor is defective by testing for continuity. Have it replaced if there is no continuity.

  1. HVAC system blower motor

Determine if you have a defective blower motor by checking if the fan blades can spin freely. If they are not spinning freely, have the blower motor replaced.

Also, replace the blower motor if it is getting power but refuses to run. The blower motor on the air conditioner cannot be repaired and must be replaced if it malfunctions.

  1. Home air conditioner capacitor

The fan cannot run if the capacitor burns out since it has electrical leads that attach it to the compressor. Test it for continuity and if the capacitor has none, have it replaced.

  1. Central ac unit rotary switch

The fan motor is activated when the rotary switch turns. If the electrical contacts become pitted, they will not conduct electricity, and the fan will not turn. Test the rotary switch for continuity after consulting the wiring diagram and have it replaced if there is none.

  1. Air conditioner selector switch

Voltage is directed to the fan by the selector switch. Make selections on the control board and if it runs intermittently after pressing buttons, have it replaced.

Also, observe the selector switch and replace it if there is any smoke or arcing coming from it.

When the air conditioner compressor refuses to run

You might discover that the compressor in your air conditioner will not run. Before you crack your head thinking what would be the problem, here are the places you should look at.

  1. Air conditioner temperature control thermostat

Electrical contacts inside the temperature control thermostat may burn out over time. If they burn out, the thermostat will turn on the fan motor, but the compressor will not work.

  1. Central air conditioner temperature control board

The fan motor and compressor get voltage from the temperature control board, and the compressor will not run if it malfunctions. Since they rarely malfunction, first check if other parts are working and pay attention to the capacitor, compressor, and compressor overload. If they are working, have the temperature control board replaced.

  1. Air conditioner thermostat

The temperature is monitored by the thermostat, and a switch is activated to power the compressor and fan when the temperature rises above a certain point. A faulty thermostat prevents the compressor from running and should be replaced.

  1. HVAC system Overload

The compressor is protected from burning out by the overload in case there is a power surge. Test the overload for continuity and replace it if there is none since it will have burned out.

  1. Air conditioner Compressor

Before you conclude that the compressor is the culprit, check all other parts if they are functioning specifically the overload protector and compressor capacitor. If you determine the compressor is at fault, have it replaced by a licensed technician.

  1. Central air conditioner thermistor

If the thermistor does not have any continuity, the compressor will not run. The thermistor detects the temperature of outside air and is connected to the control board.

Test the thermistor using a multimeter for continuity and have it replaced if there is none.

  1. Air conditioner relay board

Many air conditioner parts get voltage from the relay board, and the compressor can stop working if it becomes defective. However, since it is rare for it to malfunction, other common faulty parts should be checked paying attention to the compressor capacitor, overload protector, and the compressor.

You can replace the relay board if all other parts are functional.

  1. HVAC system air conditioner main control board

All the components of the air conditioner get their voltage from the main control board. If it has a problem, the compressor will not get any voltage. Check other parts if they are defective especially the compressor capacitor, compressor and overload protector, and if everything else is working well, you can have the main control board replaced.

  1. Air conditioner capacitor

The capacitor has electrical leads attaching it to the compressor. The compressor will not run if the capacitor has burned out. The capacitor should be tested using a multimeter for continuity, and if it does not show any signs, you should have it replaced.

  1. Central ac unit Selector switch

The selector switch sends voltage to the compressor, and if it malfunctions, the compressor will not run. Before you check the selector switch, check the overload, capacitor, and compressor and if they are working, the selector switch might be the guilty party.

Replace the selector switch if you notice the compressor running intermittently when selector buttons are pressed or when the switch knob is turned.

When the Air conditioner unit refuses to turn off

You might discover that the air conditioner keeps running and refuses to turn off. Here are common reasons why this happens.

  1. Central ac unit dirty condenser coils

As the refrigerant passes through the coils, they get rid of the heat, and they cannot do this effectively if they are dirty. Over time, they collect particles and become less efficient making your air conditioner have to work harder to cool.

Dirty condenser coils will make the compressor continuously keep running while trying to cool the room. Check the condenser coils and clean them if they are dirty.

  1. Air conditioner temperature control thermostat

The fan motor and compressor get voltage from the temperature control thermostat. Burned out thermostats send continuous voltage to the compressor keeping it running at all times.

Test for continuity using a multimeter and replace it if there is none as it will have shortened out. Remember to consult your wiring diagram to find out if the thermostat in your air conditioner has three terminals and controls a heater.

  1. Central air conditioner thermostat

Air temperature is monitored and controlled by the thermostat, and when it rises above a certain limit, a switch is activated to power the compressor and fan. The compressor will run continuously if the thermostat shortens out.

You can determine if it is faulty by using a multimeter to test for continuity. Replace it if there is none and remember to check if the thermostat controls a heater using the wiring diagram.

  1. Air conditioner thermistor

The thermistor has connections to the control board, and it detects room air temperature. The compressor will run all the time if the thermistor is faulty and when this happens, it should be replaced.

  1. Central ac unit relay board

Many air conditioner components get their voltage from the relay board. If it malfunctions, the compressor might get a constant voltage supply making it run continuously. It rarely happens, and you need to check other parts and if they are working, have the relay board replaced.

  1. HVAC system temperature control board

The compressor and fan motor get their voltage from the temperature control board. The compressor will not get access to power if it malfunctions and you should check other parts before going to the temperature control board.

Replace it is all other parts are working, and you establish the temperature control board is the problem.

  1. Air conditioner main control board

All parts of the air conditioner get their voltage from the main control board and it rarely malfunctions. Any malfunction will result in lack of power to the compressor. Check all common defective parts, and if they are all working, you can have the main control board replaced.

If the air conditioner starts making noise

You are used to peace and quiet even when the air conditioner is running. All of a sudden, there is this annoying loud noise that is driving you crazy. Well, here are the reasons for this and ways you can get your quiet air conditioner again.

  1. Home air conditioner compressor

If your air conditioner is noisy, it might be because your compressor is wearing out. If you can tolerate the noise, you do not need to replace the compressor as it can still last for a few more years. However, if you want the noise to go away, you should have a new one replaced by a licensed professional.

  1. Central air conditioner dual shaft fan motor, fan blades and fan motor

The dual shaft fan motor or fan motor has permanently lubricated bearings. After some time, the lubrication wears off making the air conditioner noisy. Replace the dual shaft motor and fan motor if the bearings wear off.

The noise from the appliance might also be caused by the fan blades scraping against the blower housing. There is a fan blade in the front and one in the rear of the air conditioner. Inspect the blades and ensure they are not scraping against the fan housing.

Replace the fan blades if you find that they are damaged, or they start rubbing against the fan housing.

  1. Central ac unit blower wheel

Check the blower wheel if it wobbles on the motor shaft. Tighten the screws or replace them if the blower wheel is loose and replace it if it is not stable.

  1. Air conditioner blower motor

Check if the fan blades are scraping against the housing. If they are not and the fan motor is still noisy, check if the blower motor bearings are worn out and replace the blower motor if they are worn out.

When the air conditioner starts leaking water

You are busy enjoying the cool air when suddenly a drop of water falls on your face. Before you hurry and start dismantling the air conditioner, here is the reason this is happening.

  1. Home air conditioner leaning too forward

If you find your air conditioner leaking water from the front, it means that it is leaning to the front a little too much. Water is supposed to be expelled from the back of the unit and for this to happen, the air conditioner must lean on a 1-2 degree angle when it is installed.

If the air conditioner remote control does not working

If you keep pressing the remote control and you find that it is not working, there could only be two reasons for it:

  1. Central ac unit remote control

First, ensure the remote control has fresh batteries. If the remote control still cannot work and the air conditioner can be operated manually, the remote control might be faulty and needs to be replaced.

  1. Central air conditioner main control board

The main control board contains an infrared receiver for remote signals. If the infrared receiver malfunctions, there will be no communication sent to the control board and it should be replaced.

When the central air conditioner coils start freezing

You might be inspecting your coils, and you find that they are freezing and you do not know why. Here are the reasons why the air conditioner coils are freezing.

  1. Dirty air conditioner air filter

Clogged air filters restrict airflow over evaporation coils. If there is limited airflow, the evaporator coils will get too cold, and this will make the humidity condense and freeze on the coils. As the coils accumulate frost, the airflow will continue being restricted and eventually it will be completely clogged. To prevent this, replace the air filter if it is dirty.

  1. HVAC system sealed system leak

If the freezing is in one place, the problem could be a sealed system leak. If this is the case, then any repairs to the system should be done by a licensed technician.

Air conditioner brand names

When doing repairs on your air conditioner, you should get parts that are made by the air conditioner manufacturer. Here are the names of brand air conditioner parts.

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