Do I need to remove the expansion valve through the engine compartment?

Hello,

The expansion valve can be accessed from under the hood. You will have to remove some wires/hoses to get to it.

Let me know of any questions.
Thank you.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

How do I access the expansion valve in order to replace it?

Hello,

The expansion valve is located on the firewall (see diagram below). You will have to remove the evaporator hose assembly to remove the expansion valve.
Keep in mind that before this can be completed the A/C system needs to be vacuumed down.

Here is a helpful guide:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

I have attached a diagram below for your reference.

Let me know of any questions.
Thank you.