Dash A/C no cool air

[CapKirk]

My RV is only 2 years old, and the A/C cool air has been getting weaker each year, this year no cool air at all. Found the Low fill side of the A/C unit and hooked up a can of r134a with its gauge, but the pressure shows 85 lbs. That tells me the compressor is not engaging and the unit pressure has equalized into the low side. I looked at fuse's but all are good, I find it hard to believe the compressor our clutch has failed so fast. And on a Diesel pusher its hard to see what the compressor clutch is doing. Is this a common problem if the A/C system gets to low. I wanted to take it in, but everywhere around here is booked 60 days out, plus I will have moved on. Can anyone pass on some experience with this problem.