Conpressor/Clutch, and Dryer  You will need to obtain, or borrow a good quality flush canister, a good vacumm pump, and if you don't have a decent set of gauges too.

 

Anyway, you must under no uncertain terms flush the system after a compressor failure, otherwise the new stuff will fail shortly.  This will be an effort on this tractor, because the only really right way to do it, is to disasemble a couple of connections, to get the componants really clean.  All the crap that came out of the compressor likes to lodge itself in the condensor, (item in front of the radiator), and the expansion valve.  So you need to get the hoses off, so you flush canister's power, is put right where it needs to be.

 

Something else I would do is remove and wash the evaporator coil (in the roof of the cab) while you are at it, typicall they get cloged pretty tightly. 

 

Once you have everything clean, then you can put it back together, put on the new compressor, and dryer.  Something I do extra to prevent seized fittings, in the future is put on some A/C tread sealant, (I get mine from Arazona Mobile Air, search online)  Then you need draw a vaccum on the system, for IMHO at least an hour, then let it set, and watch the gauges an hour or two later to check for leaks.  This is where good quality gauges come into play, some gagues don't have good graduations on the vac side, or have good sealing valves which is where you will chase a leak, that isn't even in the system you are working on.  If no leaks, this is where I put oil in the system, while under vacumm, (I have an oil injection canister also, put about a 1/3 to 1/2 of the oil dirrectly in the compressor, then the rest with the cannister), charge it with R134a, and there you go.

 

While you are at it, plan on putting in a shut off valve for the heater line, such as a ball valve, or gate valve of some kind.  A lot of the 7000 series tractors with A/C problems are really only partly the fault of the A/C system, if the control valve leaks, guess what, you are adding heat when you are trying to cool.