If hdmi on mac not working, here are some troubleshooting steps you can try:
Check the physical connections: Ensure that the HDMI cable is securely connected to both your Mac and the external display or TV. Make sure the cable is not damaged or frayed.
Verify the display input: Ensure that the external display or TV is set to the correct input source for the HDMI connection. Use the display's remote control or buttons to select the appropriate HDMI input.
Restart your devices: Restart both your Mac and the external display or TV. Sometimes a simple restart can resolve connectivity issues.
Check Display settings: Go to the Apple menu > System Preferences > Displays. Make sure that the external display is detected and configured correctly. You can try arranging the displays or adjusting the resolution settings.
Try a different HDMI cable and port: If possible, try using a different HDMI cable and connect it to a different HDMI port on the display or TV. This can help determine if the issue is with the cable or port.