What is wrong with my 2013 ford explorer, the rear AC just won't turn on sometimes?

The rear ac works great when it turns on, but sometimes it just won't. Then eventually it will turn on while i'm driving.

Do a search on youtube

AC has a high and low pressure switch… If to low or to high it won't come on… You would need to have gauge hooked up to see the pressure… It may just need a recharge…