My window air conditioner has lost its oomph. How can I diagnose it without having to go through the hassle of removing it from window?

It’s now going on its third spring/summer season. I bought it new and it worked fine for the past two years.

These are the first really hot days and it can’t get my small bedroom below 80 even tho set to maximum cooling and the overhead room fan running It used to work great and could get it to 68–70 when needed routinely with no problem at all.

Could it need a Freon recharge ? (I realize that Freon is no longer legal for environmental reasons, but I’m using the word as a shortcut for whatever the replacement is for simplicity)

About 3weeks ago I took out the filter and washed it thoroughly so it can’t be that I assume since I pulled it out enough today to check that it was not clogged.

I do have a cat who is in this room most of the day if that makes any difference.

I’m not very technically or mechanically adept so any help you can give would be much appreciated.

I’m hoping this is not a case of the modern trend toward planned obsolescense. Only two useful years is kind of ridiculous. I’m hoping I don’t have to get a new one but i have really bad allergies and sinusitis which are severely worsened with humidity. I can’t spend the rest of the summer like this.