My macbook air charger is blinking orange but not charging. How can I fix it ?

Try the following steps outlined by Apple:

If the indicator light flashes

If your battery is charging or charging is on hold, the indicator light glows amber. If the indicator light on the MagSafe 3 connector flashes amber repeatedly, try these steps:

1. Disconnect the USB-C to MagSafe 3 Cable from your Mac and from the power adapter.
2. Disconnect the USB-C power adapter from the wall outlet.
3. Use a dry cloth to wipe the MagSafe 3 port and MagSafe 3 connector. Make sure both the port and connector are dry and clear of any debris.
4. Make sure the USB-C port on the power adapter and the USB-C connector are clear of any debris.
5. Restart your Mac.
6. Connect the USB-C power adapter to the wall outlet, connect the USB-C to MagSafe 3 Cable to the power adapter and to your Mac, then try charging again.

If the indicator light continues to flash repeatedly, contact Apple.

If your MagSafe cable or power adapter isn't working - Apple Support