My MacAir (early 2015) no longer signal to my external monitor. It's been working few weeks without any issue. I tried resetting SMC and NVRAM/PRAM as recommended. Did not solve the problem. Ruled out cable and monitor issue.
Please help!
Are both Macs running the same version of macOS including the same patches?
It is possible macOS Catalina or Big Sur is not compatible with your adapter and/or monitor (or maybe just a recent update made them incompatible). I suggest booting to an older version of macOS to test this theory although if a recent firmware update is the problem instead of a software issue, then even an older version of macOS won't help. Apple has not had a great track record with macOS updates for the past couple of years.
If you don't have an older version of macOS on a bootable external drive, then you can boot into Internet Recovery Mode using Command + Shift + Option + R to access the online installer for the OS which originally shipped on this laptop from the factory. Or you can create a bootable macOS USB installer for macOS 10.11 to 10.14 using the instructions in this Apple article:
https://support.apple.com/en-us/HT201372
If you don't see any video on the external display while booting to the macOS installer, then close the lid of the laptop to force the video to the external display.
Are both Macs running the same version of macOS including the same patches?
It is possible macOS Catalina or Big Sur is not compatible with your adapter and/or monitor (or maybe just a recent update made them incompatible). I suggest booting to an older version of macOS to test this theory although if a recent firmware update is the problem instead of a software issue, then even an older version of macOS won't help. Apple has not had a great track record with macOS updates for the past couple of years.
If you don't have an older version of macOS on a bootable external drive, then you can boot into Internet Recovery Mode using Command + Shift + Option + R to access the online installer for the OS which originally shipped on this laptop from the factory. Or you can create a bootable macOS USB installer for macOS 10.11 to 10.14 using the instructions in this Apple article:
https://support.apple.com/en-us/HT201372
If you don't see any video on the external display while booting to the macOS installer, then close the lid of the laptop to force the video to the external display.
The Thunderbolt ports on the MBAir tends to collect a lot of dirt. You can try to clean the port using a toothpick, but you do need to be careful not to press too hard on the port or the contacts as you can damage the contacts even with a toothpick. It is safest to insert the toothpick all the to the back of the port, then gently press the toothpick down on the contacts while pulling the toothpick forward. You want to use a non-metallic non-conductive item so you don't accidentally short out any contacts which would be very expensive. You may also want or need to connect & disconnect the Thunderbolt cable a few times as well.
If this doesn't help, then you may need to get the laptop repaired.
I tried a different MacAir, it didn't work either. This is occurred suddenly. Is it possible because the thunderbolt/HDMI converter I'm using is not original apple product? I used other converter without luck.
My MacAir (early 2015) dose not sends signal to my external monitor.
