When switched on, the compressor attempts to start, then stops.

You say refrigerant is "full", but it can have too much. If you have attempted to "top off" your refrigerant then you may have too much, keeping the compressor from engaging. If you haven't messed with it and the compressor just stopped engaging on it's own then I would start checking the relay, fuse and the ac switch.

Since you have not listed the make or model compressor, I'll try to answer your question........ Is the compressor wired up correctley?
If the compressor is out of phase, it won't be able to perform at its peak level. Most 60-80 gallon compressores require at least 220-240 volts to operate creectly. Make sur all your presure switches are calibrated to the correct unit and the compressor should run wirtth no problems. Hope this helps.......................

There is an unloader valve and a check valve on the discharge side of the pump. The check valve is not holding and the unloader is not dumping the pressure so the compressor cannot start. Since it is new, you may want to take it back. If not you are going to be replacing parts.

Try a hard start kit sized for your fridge compressor. Local supplier should have one in the $20.00 range fairly easy to install directions on packaging just need to pull the lower back panel. if it works save up for a new fridge as this fix will last a year or two at best.

sounds like a locked rotor, did the compressor get hot? did you check max amps on the compressor when it attempted to start?compressors have thermal protection built into their windings, a switch that will open to protect the compressor, and if the rotor is locked, normally you have to replace it, you could try putting what is called a start assist capacitor on it (AKA hard start kit) I would recommend the two wire model, easy to install.
You will need to wait for the thermal overload to reset, turn power off to unit till you get the kit on there.

Hi I know these need to be very high powered so try plugging it in direct to the mains not an extension lead or use the mains from the house not a garage or outhouse hope this works!

your pressure switch is defective that controls the cycling of the motor,its fed air pressure off the tank line and opens and closes contacts to start and stop the motor to build air pressure when needed

It sounds like your inverter is at fault. You will need an inverter tester ( most good service techs will have one ) to prove that the output to the compressor is correct. If the inverter is okay then it will be the compressor at fault with a location error or it is simply seized. A common fault that caused this was the eev remained closed (coil failure ) and caused the compressor to over heat.

Sometimes, you have to start the vehicle, turn on the AC (Hi setting), and jump across (bypass) the low side pressure switch - to allow the compressor to start running and draw the freon in through the low side - make sure your fittings are correct and otherwise - Did you pull a vacuum on the system before you attempted to add refrigerant? I would highly recommend it - removes air and moisture....

You either have a problem with your compressor start relay/overload assembly.......or you have a bad compressor. You would need the model/serial number for the correct part. If the unit is out of warranty, a 3 in 1 hard start kit (Supco URCO41) can be installed. Disconnect unit from power prior to attempting repair, and follow the instructions with the part.
If the product is under 5 years, the compressor may still be under manufactures warranty. In that case attempting a repair would void the warranty.