This article outlines the step-by-step troubleshooting process when your unit has stopped cooling. Work through each section in order to identify and resolve the issue.
Before You Begin
If your unit has recently stopped cooling, it is important to determine how long the issue has been occurring. This will help identify whether the cause is power-related, airflow-related, or a mechanical component issue. Work through the steps below in sequence.
Step 1: Confirm the Unit is Plugged Into the Correct Receptacle
The first thing to verify is that your unit is plugged directly into the correct voltage receptacle.
If the unit is NOT plugged directly into a receptacle: Plug the unit directly into the correct voltage receptacle and attempt to operate the unit again. Do not use an extension cord or power bar, as this can prevent the unit from receiving adequate power.
If the unit IS plugged directly into a receptacle, proceed to Step 2.
Step 2: Check the Power Cord Light
With the unit plugged into the receptacle, check whether the indicator light on the power cord is illuminated.
If there is NO light on the power cord, this indicates a power supply issue. Take the following steps:
- Unplug the unit from the receptacle.
- Check the breaker and ensure it has not been tripped.
- Test the receptacle to confirm it is receiving power.
- Inspect the power cord for any burnt marks or visible damage.
- Test the receptacle with another unit to rule out a receptacle issue.
Once resolved, plug the unit back in and check whether the power cord light comes on. If the light is still not on after completing the above steps, contact our support team.
If there IS a light on the power cord, proceed to Step 3.
Step 3: Determine If the Unit is Running on a Thermostat
If the unit IS running on a thermostat: Remove the unit from thermostat control and switch to display mode directly on the unit. Check whether the issue persists when operating from the unit display. If the unit begins cooling in display mode, the issue may be related to the thermostat connection or thermostat settings. For further guidance, see our article on Thermostats vs. PTAC Controls.
If the unit is NOT running on a thermostat, check the unit display for any error codes before proceeding.
- If an error code is displayed: Check our Help Centre for guidance on E9 error codes and refer to the E9 Error Code Troubleshooting Guide.
- If no error code is displayed, proceed to Step 4.
Step 4: Check Airflow and Clean the Unit
Restricted airflow is one of the most common causes of cooling issues. Before investigating mechanical components, ensure the unit and its surroundings are clear.
- Check the indoor intake and exhaust air vents to ensure they are not blocked.
- Remove the front cover and check the filters — clean or replace them if dirty.
- Inspect the indoor coil for any blockage or debris buildup.
- Slide the unit out of the sleeve and check that the outside of the unit is free of debris. Ensure nothing is blocking the condenser coils or the outdoor fan.
Once the unit is cleaned and reinstalled, attempt to run it in cooling mode again. If the issue persists, proceed to Step 5.
Step 5: Check Whether the Indoor Fan Comes On
Set the unit to cooling mode and observe whether the indoor fan starts.
Expected order of operation:
- Indoor fan
- Compressor
- Outdoor fan
If the indoor fan does NOT come on:
- Check the fan motor for any signs of damage.
- Check the capacitor.
- Check for any blower wheel obstruction — confirm the fan can turn freely by hand.
Address any of the above findings before proceeding. If the indoor fan is running, check whether there is a temperature difference between the room temperature and the air coming from the exhaust. If you notice no temperature difference, proceed to Step 6.
Step 6: Determine If the Compressor Is Starting
Listen carefully when the unit is running in cooling mode. The compressor should produce a noticeable humming sound when it starts.
If the compressor is NOT starting (no humming or clicking):
- Check the compressor capacitor. For guidance on how to test the capacitor, visit our Compressor Capacitor Testing Guide.
- Check the control board output.
- Check the compressor overload.
- Verify that the correct voltage is being supplied to the compressor.
Note: Be sure to ground the capacitor before testing it.
If the compressor IS starting, proceed to Step 7.
Step 7: Check Whether the Outdoor Fan is Running
With the compressor running, confirm that the outdoor fan also comes on.
If the outdoor fan is NOT running:
- Check the outdoor fan motor.
- Check the fan capacitor.
- Check the control board output.
If after completing all of the above steps the unit is still not cooling, please submit a support request and our team will be happy to assist you further.
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