Troubleshooting6 min read

Why Is My AC Not Cooling? Common Causes

The most common reasons your air conditioner is not cooling, safe checks you can perform yourself, and when to call a licensed technician.

Safety Note: Gas recharge, compressor issues, outdoor unit faults, and electronic board problems require a licensed technician. Do not attempt to access these components yourself.

Step-by-Step Guide

  1. 1

    Check and clean the filters

    Clogged filters are one of the most common causes of reduced cooling. Remove the filters, check for heavy dust, and clean if needed.

  2. 2

    Verify the operating mode and thermostat setting

    Confirm the remote control is set to COOL mode. It is easy to accidentally leave the unit in FAN or HEAT mode. Set the target temperature at least 2–3°C below the current room temperature.

  3. 3

    Clear airflow obstructions

    Check for curtains, furniture, or other objects blocking the indoor unit. Restricted airflow significantly reduces cooling efficiency.

  4. 4

    Restart the unit

    Turn off the AC, unplug it, wait 10 minutes, then restart. This can clear temporary electronic faults.

  5. 5

    Note any error codes

    If an error code appears on the display, write it down and look it up in our error code guide. Error codes often point directly to the cause of the problem.

Frequently Asked Questions

The AC is running but not cooling — could it be low on refrigerant?

Low refrigerant is one possible cause, but you cannot check this yourself. After performing the safe checks above, if the problem persists, a licensed technician can measure the refrigerant pressure.

The outdoor unit is not running and the AC is not cooling — what should I do?

An outdoor unit that is not running may indicate a compressor fault, electrical connection issue, or a tripped safety switch. Do not attempt to access the outdoor unit yourself — contact a licensed technician.

A newly installed AC is not cooling — what should I do?

Cooling problems in a new installation are often related to a refrigerant leak, incorrect installation, or a wiring issue. Contact the installation company or authorized service.

The AC only fails to cool at night — why?

If outdoor temperatures remain high overnight, AC efficiency can drop. Poor room insulation, heat entering through windows, or an undersized unit are also possible factors.