Window AC Repair Guide: Tackle Common Problems Like a Pro

The summer sun is beating down, and you turn on your window AC unit. But you feel nothing. There is no cold air coming out of the vents. Your trusty window air conditioner has failed you, leaving your home feeling like a sauna.

Before rushing to call in professional help, consider troubleshooting your window AC yourself. In many cases, you can resolve the issue without requiring expert help, saving money in the process.

This window AC repair guide dives deep into troubleshooting common window AC problems. It will equip you with the knowledge to diagnose the issue and walk you through simple repairs you can perform yourself.

Window AC Components to Inspect for Repairs

Before diving into the window AC repair process, it’s essential to get yourself familiar with the various AC components.

• Face Panel or Grille Cover

The face panel is the grille cover in front of your air conditioner. You must first remove it to make repairs.

• Filter

Upon removing the grille cover of your window AC, you will immediately see a thin covering that protects the internal components of your air conditioner from any external dirt and particles. This protection sheet is called an air filter; without it, the dirt particles may cause irreversible damage to your air conditioner.

• Evaporator Coils

They are copper tubes that contain refrigerant, which cools the hot air.

• Refrigerant

Refrigerant is a liquid substance that helps provide cool air to your room. It moves through the evaporator and condenser coils of an air conditioning system, facilitating the generation of cool air.

• Condenser

The condenser, located at the back of a window air conditioner, expels hot air from your room.

• Condenser Coils

Condenser coils are located at the very back of the AC unit. They are composed of elements similar to the evaporator coils, with copper tubes and refrigerant. These coils receive the hot refrigerant from the evaporator coils through the compressor and release that heat outside.

• Compressor

It is responsible for converting refrigerant from liquid to hot gas.

• Fan Blower

The fan blower is located near the evaporator coils. It first pulls the room air inside and on the evaporator coils so that the refrigerant inside them can absorb the heat in the air and cool it. Then, the fan blows this cool air back into your room.

• Capacitor

An air conditioner capacitor is a component that stores and releases electrical energy to help start and run the AC motors. It provides the initial jolt of power needed for the motors to run efficiently.

• Thermostat

The thermostat in the window AC is the small tube typically attached to the evaporator coils. It plays a crucial role in regulating the air conditioner’s on/off cycle. It monitors the room temperature to determine whether to start the cooling cycle.

• Drain Pan

The drain pan is usually located beneath the evaporator coil to gather the moisture that results when the warm air is cooled against the evaporator, causing it to condense. The pan is tipped towards the back of the air conditioner unit to let the water drain through the drain port, preventing it from leaking inside your room.

How to Fix 10 Common Window AC Issues

Your window air conditioner can sometimes run into problems. Some common examples include refrigerant leakage, insufficient cooling, and frequent on/off cycling.

Problem	Causes	Solutions
Window AC not blowing cold air	Dirty filters and Coils Damaged sensors Compressor failure	Clean filter coils Adjust sensor wirings Replace compressor
Window AC has power but is not turning on	Tripped circuit breaker Damaged power cord Faulty wiring, compressor issues, and malfunctioning control board	Check for circuit overload Replace the damaged power cord Consult an HVAC professional
The window unit turns on and off too quickly	Corroded electrical connection, damaged compressor and fan controls	Call a pro for a thorough inspection
Window AC Is Running Non-stop	Damaged internal thermometer	Replace the thermometer
Your window unit has low refrigerant levels	Insufficient pressure charge or refrigerant leakage	Requires professional assistance to fix the leak and recharge the refrigerant
Window AC repeatedly trips your circuit breaker	Overloaded circuit	Provide a dedicated circuit
Water leaking from window AC	The drain pan is not tilted properly Misalignment between drain pan and drain port Drain hole blockage	Inspect the drain pan to make sure it is tilted properly. Ensure the AC unit is level with the window Unclog the drain hole
AC is freezing up	Dirty filters &coils, refrigerant leakage, or compressor failure	Thaw the ice and let the unit dry completely. Consult a pro to diagnose the root cause of this issue.
The window unit making strange noises	Banging or screeching noises indicate Issues with fan components A rattling noise means leaves and debris are stuck inside Improper window AC installation can cause vibrations	Lubricate the fan motor or straighten the bent fan blade Clean the outdoor part of the AC and trim the vegetation around it Ensure proper installation
Weird smells coming from the unit	Exhaust fume smell means refrigerant leak Gun metal odor means a shorted-out fan or circuit board A musty smell indicates microbial growth	Consult professional Shut off the unit and contact a professional Thoroughly clean the moldy areas

Note: While homeowners can handle issues like cleaning and removing obstructions, any electrical work should be left to professionals for safety reasons. Also, consult a pro if you encounter complex problems or are unsure how to proceed to ensure safe and effective AC repairs. Be sure to turn off your window AC before investigating any issue. You can do this by unplugging the cord from the wall outlet or switching off the breaker.

1. Window AC Is Not Blowing Cold Air

There can be several possible reasons why your window AC is not cooling properly. Some of the most common ones include:

• Dirty Filters & Coils

When air filters become clogged with dust, debris, and other pollutants, they restrict airflow into the unit. As a result, the air conditioner struggles to cool the air passing through it, leading to reduced cooling capacity and potentially causing the unit to blow warm air. Clean them every two weeks and replace them every three to four months.

The coils in your air conditioner play a vital role in transferring heat from inside your home to the outside air. When these coils become dirty, their ability to efficiently transfer heat is compromised. You can easily clean them using a soft brush or a cloth. Here’s a detailed guide about cleaning your AC coils.

Handy Tip: Pair your window unit with a window AC thermostat, also known as a smart AC controller, to receive maintenance reminders whenever your filter cleaning is due.

Related: How to Clean Your Window AC Unit in 8 Simple Steps

• Damaged Sensors

Room air conditioners rely on sensors to gauge the temperature of the room and regulate the flow of coolant accordingly. However, if these sensors malfunction or break, it can result in issues such as constant cycling or the inability to reach the desired temperature.

One common fix for sensor-related problems involves adjusting the sensor wire so that it is positioned near the coil but does not make direct contact with it. This adjustment ensures that the sensor accurately detects the temperature. You can easily make this adjustment yourself, but be sure to turn off your AC before proceeding.

• Compressor Failure

If your AC consistently blows warm air despite clean filters and fins and no other visible issues, it could indicate a compressor failure.

The compressor is a pivotal component in any air conditioning system. When the compressor is not functioning properly, it hinders the flow of cold air, resulting in inefficient operation of the air conditioner.

Given the significant expense associated with replacing a compressor, opting for a new window air conditioner is a more cost-effective solution in such cases.

2. Window AC Has Power but Isn’t Turning On

If your window air conditioner fails to turn on, the first step is to verify whether it’s receiving power. Unplug the unit and plug it into a different outlet to confirm power availability.

If your unit still doesn’t turn on, check your circuit breaker for tripping, as circuit overload can cause it to cut power to the air conditioner. Ensure the breaker can handle the required amperage, as indicated on the AC’s rating plate. Additionally, inspect for any signs of damage to the power cord, such as chew marks from animals or accidental damage caused by someone tripping over the cord.

Your window AC may not turn on due to faulty wiring, issues with the compressor, problems with the selector switch, or a malfunctioning control board. In such cases, it’s advisable to seek assistance from your local window AC repair technician.

Related: 13 Reasons Your AC Is Not Turning on & How to Fix Them

3. Window Unit Turns on and off Too Quickly

There can be various underlying causes if your air conditioning unit cycles on and off frequently. It’s best to consult a professional in this case. They will thoroughly inspect your window unit, focusing on electrical connections for signs of corrosion. Additionally, they will assess components like the compressor and fan controls, which, if worn out, can lead to rapid cycling of the unit.

4. Window AC Is Running Non-stop

A constantly running window AC indicates a malfunctioning thermometer. This component inside the window AC monitors the temperature of the surrounding area to determine when to activate or deactivate the compressor. When the area reaches the desired temperature, the thermometer signals the compressor to shut off, or it keeps running if the area remains too warm.

To locate the thermometer in your window air conditioner, remove the outer shell to access the electrical control board. The thermometer is typically a small copper tube positioned on or near the control board. Inspect the thermometer for any signs of damage or disconnection, and if found, consider replacing it. You can undertake this replacement yourself, but ensure to use a new thermometer approved by the manufacturer for your specific window air conditioner model.

Related: How Do Window AC Units Work & Other Frequently Asked Questions

5. Your Window Unit Has Low Refrigerant Levels

If your AC circuit breaker keeps tripping, it indicates that your unit is drawing too much power and is overloading the circuit. One solution to this problem is to provide the AC unit with its dedicated circuit, ensuring it has sufficient power to operate without causing disruptions.

7. Water Leaking From Your Window AC

The drain pan in your air conditioner is designed to collect the moisture produced by the evaporator coils. It’s strategically angled downward to facilitate the drainage of water through the back of the AC unit. If you notice your AC leaking water, inspect the drain pan to ensure it’s properly tilted for effective drainage.

A misalignment between the drain pan and the drain port can also result in water leaking inside. It often occurs when the AC unit is not level in the window. To address this issue safely, start by unplugging the AC unit. Then, adjust the position of the unit to ensure it is leveled properly.

Another possible cause of water leakage could be drain hole blockage. Dirt and debris can build up inside the window AC drain hole, causing water to leak instead of draining properly. Here’s a complete guide on how to find the drain holes on your window AC and unclog them.

8. Your AC Is Freezing Up

If you notice ice forming on your air conditioner in the middle of a hot summer day, it indicates a problem that requires immediate attention. The most common reasons for this issue include dirty filters and coils, refrigerant leakage, compressor failure, and inadequate HVAC airflow.

To address this issue, you will first need to thaw the ice. Start by turning off the air conditioner. You can let it air dry, but to speed up the drying process, you can use your hair dryer. Allow the unit to dry completely before turning it on. In the meantime, contact a window AC repair professional to diagnose the root cause of the ice formation and implement the necessary repairs to prevent future occurrences.

9. Window Unit Making Strange Noises

Loud AC noises like banging, buzzing, or rattling indicate potential issues that require attention.

Banging or screeching noises often indicate problems with various fan components, such as the fan belt, blades, or motor. Simple fixes like lubricating the fan motor or straightening a bent fan blade may resolve the issue. However, more severe damage will require professional assistance to replace the fan belt.

The sudden rattling sounds indicate that a foreign object has likely fallen into your window AC. Leaves and debris commonly find their way into the slats on the exterior, causing disturbances as they hit the fan inside. Trim the leaves and vegetation around the outdoor unit to prevent this issue.

Improper installation of the unit in the window can also cause your AC to make noises, as it may vibrate against the window sill or frame.

10. Weird Smells Coming From Your Window Unit

Various smells coming from your AC unit can indicate different issues:

• Exhaust fume smell: This could signal a refrigerant leak, releasing chemicals into the air. Turn off the unit immediately and ventilate the space. Consult a professional to fix the leak.
• Gunmetal odor: This smell may occur if the unit’s fan motor or circuit board is shorted out. It’s advised to shut off the AC unit upon detecting this odor.
• Musty smell: Moisture accumulation within the system can lead to microbial growth, causing this odor. To clean the mold, mix antibacterial soap with warm water and spray the solution on the black mold you see on your unit. Then, use a scrub brush to clean off the areas. Wipe down the area with a clean cloth. After this, spray the interior and exterior with hydrogen peroxide solution to prevent mold growth in the future.

Window AC Repair Cost

The average cost of repairing a window AC unit falls between $106 and $363, with typical expenses around $234. These estimates include hourly labor rates ranging from $50 to $100 per hour and replacement part costs from $2 to $150.

Replacing vs. Repairing Window AC Unit

If fixing your window AC unit will cost more than half the price of buying a new one, it’s best to just get a replacement. This is particularly true if your AC is approaching the end of its lifespan, which is 8 to 10 years. However, for minor repairs like filter or fuse replacements, it’s usually more practical to proceed with the repair rather than investing in a whole new unit.

Window Air Conditioner Maintenance Tips

Regular HVAC maintenance is essential to prevent issues from arising. It ensures your window AC runs smoothly, especially during the scorching summer months.

For optimal performance, it’s recommended that your window unit air conditioner be cleaned at least once a year. If your window AC unit provides cooling only, springtime cleaning before the peak of summer is ideal. For window heat pumps that offer both cooling and heating functions, cleaning twice a year, in spring and autumn, is preferable.

1. In addition to annual maintenance, it’s essential to clean or replace the filters regularly to ensure proper airflow.
2. Regularly inspect and clean the coils to prevent dirt buildup, which can hinder the unit’s performance.
3. Vacuum the entire AC unit to eliminate any dust or debris that may have accumulated during the off-season.
4. Periodically spraying the unit with hydrogen peroxide can help prevent mold growth.
5. If you are installing a new window AC, thoroughly clean windows, including wiping down tracks and scrubbing screens, to allow unobstructed airflow.
6. During colder months, cover and store the unit away from dust and debris to keep it in good condition until it’s needed again. Before storing it, make sure to clean it thoroughly. Here’s a detailed guide on how to properly store your air conditioner for winter.

Related: HVAC Preventative Maintenance: Complete Guide With Checklist

Final Takeaway

You can handle most of the window AC repairs yourself and save money. Just make sure you have the right tools and a basic understanding of how your window AC works and its main components. Start by identifying the problem and determining which part needs attention. For example, if your AC isn’t cooling effectively, try cleaning or replacing the filter. If your AC keeps tripping the circuit breaker, consider providing it with a separate electrical circuit. If, at any point, it gets confusing, you can always ask a professional for help. And remember, keeping your AC well-maintained is highly important. Regular AC tune-ups will help keep your unit running smoothly, prevent unexpected issues, and help you enjoy a comfortable indoor climate all summer.