Air Conditioner Plugin/Breaker Help?

We just bought a new air conditioner. It is HOT here in Georgia!!! The unit is a 18,500btu and runs on 230v. To be precise the male plug is 230v 15a. The plugin where the new air conditioner fits is where the old one came out. The receptacle has a NEMA 6-20 plug instead of the NEMA 6-15 female receptacle. The new air conditioner male plug fits into the old receptacle though. I guess I am asking, is this safe? Dad said it is fine. The air runs, but I don't want any damage to a $550 air unit. Also, the plug is wired to a 30a breaker. Is this a problem also? I assume it should be a 15a breaker and a NEMA 6-15 plug. Too much to be safe, right? I am TERRIFIED of fire, having lost my pawpaw to an electrical fire. Can someone help me and give a little advice to tell an electrician if I need to call one? Any advice is so gratefully appreciated!

 

The outlet is fine....................change the breaker to a 20 or 15 amp..............
Look in the book that came with the a/c and it will tell you what size circuit you need …...............if it has 15...............use a 15 amp breaker and make sure that the wire is 14 gauge or larger.

If it says 20....use a 20 amp breaker and make sure that the wire is 12 gauge or larger.

 

Thank you so much! I do appreciate it.