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LED every 1 sec

ERR/NET LED flashes every second — Invalid DNS setting

Mitsubishi Electric · MSZ-AP Air Conditioners

What does LED every 1 sec mean?

The ERR or NET LED on the Wi-Fi interface is flashing once per second, signaling an issue with the DNS (Domain Name System) settings required for internet communication.

Common Causes

  • Invalid DNS settings on the Router
  • Incorrect DNS address settings on the Wi-Fi interface
  • Router unable to resolve DNS addresses

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the DNS settings of your Router and ensure they are correct and functional.

  2. 2

    Verify the DNS address settings configured for the Wi-Fi interface.

  3. 3

    If settings appear correct, push the RESET Button on the Wi-Fi interface for more than 15 seconds to retry pairing.

  4. 4

    Try using public DNS servers (e.g., Google DNS 8.8.8.8) in your Router settings temporarily to test.

Browse all codes in this manual (87)
Verified technical data. Last updated: April 2026

Related Faults

3 Min Restart DelayUnit cannot be operated for about 3 minutes after restart - Microprocessor protection3 Short Beeps3 short beeps from indoor unit - Weekly timer setting failedAP Mode activatedNET and MODE LEDs flashing (every 5 seconds) - Access Point Mode activated
Source: Mitsubishi Electric MSZ-AP Air Conditioners
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