A/C only blows cold while driving?

Yep, it looks like the A/C compressor is going out, the high side is too low. How much refrigerant is in the system? There should be 1.7 pounds.

Here is how to change the compressor out with instructions below for your car:

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Check out the images (below). Let us know how it goes.

Yes, it is, sorry I should have mentioned that. Here is the location, check out the images (below). Let us know how it goes.

Yep, the receiver dryer can be tough to get to, I would open the system after the refrigerant has been removed and see what it looks like, there are two ways a compressor with stop working, messy and not. I other words are the compressor seals spread throughout he system or is the system clean inside, this will determine if you need the expansion block or not. You can upload an image or video of the inside tubes once apart so I can tell.

Yes, you should be able to see the dye. If the front of the compressor is leaking, which is common it can be difficult to see.

Yes, do you have a leak detection device? Please go over this guide to see what I am talking about.

https://www.2carpros.com/articles/air-conditioner-leak-detection

Please go over this guide and get back to us.

I have not seen those work but you never know, if you have a leak detector and can sniff the evaporator drain tube as in the guide above.

It will be on the passenger's side at the lower part of the firewall.