Plug Adapter Converter

Is there a converter or adapter for a NEMA 10-30 plug and NEMA 6-15 or 6-30 receptacle?

I have a whirlpool 220v a/c. It recently stopped working. My grandfather had a spare 220v a/c but it is pretty old. It's a 27000 BTU Coronado Aristocrat 270 Model ACE937A. We put the unit in the window, but when we went to plug it in, the receptacle is completely different than the plug.
The plug is a NEMA 10-30. The receptacle is either a NEMA 6-15 or 6-30 (I don't know how to tell the difference).
I don't have the cash to get the whirlpool fixed or to buy a new unit right now and it's hot as hell here.
Is there an adapter that will resolve my problem and if so, where can I get one?

No, there is no adapter. A Nema 10-30 is a 125/250 volt plug rated at 30 amps. If the receptacle is a 6-30 it is also rated at 30 amps and should be wired for 250 volts. You could replace the plug on the air conditioner as Mark mentioned. Or change the receptacle to match the AC plug. But if the receptacle is a 6-15, it is only rated at 15 amps and will not handle a 30 amp load. Quick check - go look for the AC circuit breaker. If it is a 30 amp you should be ok. If it is 15 or 20 it most likely will trip with the larger AC unit no matter what plug you put on. At least I would hope so. The alternative is an overheated receptacle and fire. Plugs and receptacles are configured so you cannot plug in the wrong thing and cause a fire. That is why no adapters are made. I hope this helps. Call an electrician if you have any doubts. Don't cause a fire or get hurt.
Here are your plugs and receptacles:

http://www.stayonline.com/reference-nema-straight-blade.aspx