MacBook Air fan

Try this:

How to reset the SMC of your Mac - Apple Support

The SMC is responsible for managing behaviors related to the following features. If you're experiencing issues with any of these, you might need to reset the SMC. 

• Power, including the power button and power to the USB ports
• Battery and charging
• Fans and other thermal-management features
• Indicators or sensors such as status indicator lights (sleep status, battery charging status, and others), the sudden motion sensor, the ambient light sensor, and keyboard backlighting
• Behavior when opening and closing the lid of a notebook computer

Good luck!

I just realiced you said you had a macbook air 2017 model.

If so follow the steps under:

Notebook computers with a non-removable battery

This applies to all MacBook Air models, as well as MacBook and MacBook Pro models introduced in mid 2009 or later, excluding the MacBook (13-inch, Mid 2009).

1. Shut down your Mac.
2. On your built-in keyboard, press and hold all of these keys:

• • Shift  on the left side of your keyboard
  • Control  on the left side of your keyboard
  • Option (Alt)  on the left side of your keyboard

1. While holding all three keys, press and hold the power button as well.

2 Keep holding all four keys for 10 seconds.

3 Release all keys, then press the power button to turn on your Mac.

Make sure you hold in the buttons for your type of mac, because yeah that's not whats supposed to happen.

If you still can't get it to work

Contact Apple for support and service - Apple Support