Sure, you can do it. I used to do a lot of automotive work and once I realized that most of the tables were r134a I figured I’d try. I bought a set of gauges (150) and I had a canister of r134a, but you can get it at the auto parts store. It was every bit of 150 to get somebody just to come out and add some freon. One of my tables is a 5 yr old Larosa. I have had three different places look at it and none of them could find the leak. So, when it starts acting up I hook my gauges up and check it and top off if needed. I would definitely try to talk somebody into showing you the basics if you are not familiar. And definitely make sure you are using the right refrigerant. I couldn’t survive if I didn’t fix as much as I can myself.