If you read my suggested letter carefully, you’ll see that in the absence of a positive response by your neighbour and the Owners Corporation you’re only making arrangements to have the air conditioner removed and to make an Application to the NCAT.
Whether you actually do that depends upon the response that you receive and how comfortable you are with taking the next step if it comes to that, because as I’ve said already it’s YOUR letter so don’t write and issue anything that you’re not happy with!