'I don't believe the refrigerant leaked out (no way to check it), as it worked one drive and didn't at all the next.'

That could be wildly incorrect. Your issue there is time not mileage, time for the refrigerant to slowly leak out like most of them do over the years. Once you hit 25 psi the a/c will NOT be coming back on.

The relays can have the covers removed to work the switchplate by finger to see if they are bad or not.

 

...My owner's manual shows only the compressor clutch relay location, is there a compressor control relay, and if so, where? Thanks in advance.

No. There is only one relay.

The compressor (clutch) cycles on & off at the discretion of (1) the cycling switch (2) the PCM. These two items work together, and turn on & off that relay... which of course is turning the compressor clutch on & off.

I recommend that the system should be checked for "basic" pressure before chasing possible electrical control problems ((not including basic electrical checks)). This pressure test/check can be performed without the system running. Many car repair shops can do this, and should cost less than you might fear. Free or with little costs. Most shops are looking for MONEY to repair it, and not the initial quick check/visit. Just ask them for ONLY a basic pressure test, and not for a full diagnosis, which could get expensive. This is assuming you want to find & fix it yourself, -and to save money.

Anyone with a gauge-set, and knows how to use it, could help you, in order to get the basic pressure test done.

Gd Luck