new air conditioner or repair 10 year old unit

The rules of thermo dynamics havent changed so the new ones arent really any more efficient.

But labor rates have gone up. I replaced the motors on mine that failed about two weeks apart. A little over a hundred each but if it is the compressor I would replace the entire unit.

It could also be something cheap like the starting capacitors or the startup device PTCR.

Depends how handy you are. You might try to find a decent rv guy that says he can take a look.