Window air conditioner isn’t blowing cold air: 8 causes & solutions

If you have a window air conditioner that doesn’t blow cold air, you’re not alone. But you don’t have to let a malfunctioning unit ruin your comfort in hot weather. You may be able to fix the unit yourself by following the troubleshooting steps in this guide.

If you find out that you need any replacement parts for your air conditioner while you’re troubleshooting, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

Important: The troubleshooting information provided in this article may not apply to your specific appliance model. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

What you need

• Multimeter
• Screwdrivers
• Vacuum cleaner
• Fin comb

Important: The specific tools required may vary depending on the model of your appliance and the type of fasteners used on it. Always consult the user manual or refer to any specific instructions provided by the manufacturer for the recommended tools for your appliance model.

Read more:  How To Replace An Air Conditioner Condenser Fan Blade 

Safety precautions

When working on any appliance, remember to keep safety first. Here are some tips to keep in mind:

• Always power off and unplug your appliance or switch off the circuit breaker before you attempt any maintenance or replacement work. This keeps you safe by eliminating any risk of electric shock.
• If the appliance has recently been used, give it plenty of time to cool down before working on it.
• Take your time while working to prevent accidents and personal injuries. Rushing is the enemy of precision.
• Work in a well-lit area so you can see and access appliance parts.
• Keep your workspace free of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with wet hands. Make sure the work area is completely dry.
• Check the user manual to see if there are specific installation or safety instructions related to your appliance or replacement part.
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause personal injury.
• Wear insulated work gloves to protect your hands from sharp metal parts and debris.
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.
• Always take photos or make a note of wiring terminals or other connections before disconnecting them to make reassembly easier.
• Don’t test live voltage with a multimeter if you’re unfamiliar with how to prevent short-circuiting.

Read more: How to get better air quality from your window air conditioner

What to check on an air conditioner that doesn’t blow cold air

Follow these steps to troubleshoot a window air conditioning unit that runs but doesn’t blow cold air.

Step 1: Check the airflow

• Inspect the air filter and clean it or replace it if it’s severely clogged or damaged.
• Check the condenser coils and fins for any debris or blockages.
• Use a vacuum cleaner with a soft brush attachment to gently clean the coils. Use a fin comb to straighten any bent fins.

NOTE: Don’t operate the unit if the ambient temperature is below 70°F, since this can cause the evaporator coil to freeze up.

Step 2: Test the fan switch (if applicable)

If you have a mechanically-operated AC unit:

1. Set a multimeter to continuity mode.
2. Use the meter probes to test the fan switch for continuity if applicable. The meter should make a beeping sound if there’s continuity.

If you don’t get continuity, replace the switch. If you got continuity, continue troubleshooting.

Step 3: Check the fan motor capacitor

1. Unplug the AC unit from the power source.
2. Use an insulated screwdriver to carefully discharge the capacitor by creating a short circuit between the two terminals.
3. Set a multimeter to capacitance mode and use the probes to check the capacitor’s capacitance value. Make sure it’s within the specified range for the specific model by referring to the unit’s technical sheet. If the capacitor is out of specification or shows visible signs of damage, it will need to be replaced.
4. With the capacitor discharged, use the multimeter to test the resistance of the fan motor windings. If the fan motor windings are out of specification, then the fan motor will need to be replaced.

Step 4: Check the fan motor

1. Remove any foreign objects that may be jamming the fan motor.
2. Inspect the fan blades for any damage and replace the fan if needed.
3. Check the fan motor bearings for binding and lubricate or replace the motor if the bearings are faulty.

Step 5: Test the thermostat

1. Make sure the thermostat is set correctly.
2. Use a multimeter set to continuity mode to check the thermostat for continuity. The meter should make a beeping sound if there’s continuity. If there’s no continuity, replace the thermostat.

If the thermostat doesn’t pass testing, replace it.

Step 6: Test the temperature control switch (if applicable)

If you have a mechanically-operated AC unit:

1. Find the temperature control switch, which is typically located on the air conditioner’s control panel. This switch allows you to set the desired temperature.
2. Set your multimeter to continuity mode and turn the temperature control switch to the coldest setting.
3. Touch the multimeter’s probes to the terminals of the temperature control switch. The multimeter should indicate continuity and make a beeping sound at this point.
4. Turn the switch to the warmest setting and touch the meter probes to the terminals. The continuity should be broken and the meter shouldn’t make a beeping sound here.

If the temperature control switch doesn’t pass testing, replace it.

Step 7: Check the compressor capacitor

1. Make sure the unit is unplugged from the power supply.
2. Use an insulated screwdriver to carefully discharge the compressor capacitor by creating a short circuit between the two terminals.
3. Visually inspect the capacitor for any signs of damage, such as bulging, leaking, or discoloration. If the capacitor is damaged, it will need to be replaced.
4. Set a multimeter to measure capacitance and use the probes to check the capacitor’s capacitance value. Make sure it’s within the specified range for your particular model by referring to the technical sheet. If the capacitor is out of specification, replace it.

Step 8: Check the start relay

1. Make sure the unit is unplugged from the power supply.
2. Consult the wiring diagram for your specific AC model to find the start relay’s terminals and how to properly test it.
3. Set a multimeter to continuity and use the probes to check the start relay’s contacts for continuity. The meter should make a beeping sound if there’s continuity.

If you don’t get continuity, replace the start relay.

NOTE: If you have a unit with a control board and you’ve made it this far, test the thermistors according to the manufacturer’s specifications. As a last resort, replace the main control board if everything else passes testing.

Read more:  How to troubleshoot & fix common window air conditioner problems 

More for you

Thank you for reading! We hope this guide helped you fix your window AC!

If you have any other appliance repair needs or projects, don’t hesitate to explore our other troubleshooting guides and videos.

If you need replacement parts or some extra help with ordering them, grab your model number and head over to AppliancePartsPros.com, where you can chat with a pro, read our DIY blog and more.

Don’t forget to subscribe to us on YouTube and follow us on Facebook, Twitter and Instagram!