sd card not detected by MacBook Air early 2014

Are you looking in Disk Utility?

Do you have another SD card to test with?

The slot may be faulty.

Ciao.

The SD card should appear in Disk Utility id everything is functioning correctly. If the card is good and does not appear, then there is probably a hardware fault. An appointment at an Apple store genius bar for a FREE evaluation is a good option.

Ciao.

Same problem with my Macbook Air 6,2 with El Captain 10.11.3 (though this error occurred with previous OS's). Sporadically, when I insert the SD card, it doesn't mount properly. SD card is fine & works in camera and other devices (and also in my MacBook Air when it feels in the right mood). I checked with the Disk Utility and the card is there, only not mounted. Size and partition are displayed OK; when I click in 'mount', nothing happens.

After a few (or many) attempts, eventually it will work. Any hints?

Here's the result of checking with Disk Utility (I'm sorry the text is i Portuguese, but it is easy to figure out the relevant information).

First image from a SanDisk Extreme PRO, 95MB/s, 32GB capacity. This one worked everytime.

Second image, SanDisk Extreme PLUS, 80MB/s, 32GB capacity. Unmounted; showed up on Disk Utility but not on Finder.

Then, after several attempts (removal/insertion), the second card finally showed up as mounted in Disk Utility and then Finder could find it.

The only (significant?) difference between them is the speed; both have been formatted in the camera and have been used alternately. I have used cards of different capacities and speeds in the past and had problem with most of them.

Bring the MBA in for testing. The symptoms you describe suggest a hardware connection problem.

Ciao.