MacBook Air will not start up. only emits sequence of 3 beeps
how do i repair this MacBook Air
MacBook Air 13″, macOS 10.13
Question marked as
Assuming you mean three beeps, pause, three beeps, pause, etc., then Contact Apple for service. That startup tone means a fault with the RAM, and the RAM is soldered to the logic board on all models of MacBook Air meaning you can't replace it yourself.
About Mac startup tones - Apple Support