Compressor won't start, fan motors both running OK, fuses OK. Was OK last time used. Older York a/c model # cl 42-6a.

I would start by having the compressor capacitor checked.

I agree that's the first place to start. Run capacitors go bad all the time. It's a cheap part and most hvac companies will test it for free if you take it to them in hopes of a parts sale.