Buying it is one thing, but fitting it is something quite different.
Fitting a new part is something you need to know how to do.
If there is silver soldering involved you should trickle dry nitrogen though
the system while silver soldering it, otherwise you will get pollution in
Once the coil (or what ever) is fitted you need to evacuate the system with
a good vacuum pump and have a high vacuum gauge connected to ensure you
remove all the air and moisture.
If the air and moisture is not removed the chances are it will cause the
compressor to burn out.
If there is pollution from the welding in the system it too will cause
Charging the system with gas requites the exact amount of refrigerant and
the correct refrigerant as most refrigerants are not suitable from the
original one Some need different oils and it is a big and complicated job to
change the oil.
If you change the coil and burn out the compressor it is a lot more
expensive that getting an expert in to do the original job.