Can I splice a 30 amp cord to a 15 amp cord for AC
 

I am new and I hope someone can help. My dryer outlet uses a 30 amp cord/plug but my new ac unit uses a smaller 15 amp plug. Can I splice a 30 amp extension plug into a 15 amp wire plug to hook up my air conditioner? My ac plug is a 230 volt 15 amp but I only have a dryer hook up that requires a 30 amp style plug. Thanks

Yes you can change the plug but you also have to change the breaker. If your cord and machine want 15 amps that's the breaker you want to use.

No you can't change the plug. You must change the double pole 30 amp breaker to a double pole 15 amp and the receptacle 15 amp 240 volt to match the AC.

What will you use to power your dryer?
If your asking can you power both the dryer and the A/C from the same circuit, the answer would be NO.

Sorry I didnt say was that I would unplug the dryer when I would want to use the outlet and only for the ac when needed or vice versa. I would only use either one at one time as there is only one outlet. I have a 30 amp cord to plug into that outlet but wanted to splice the 15 amp cord/plug to the ac unit. Is it ok to splice the 2 cords together? Thanks

I thought you were leaning towards something like this but, unfortunately you can't do that.

Your AC is a 15 amp device with a 15 amp cord and plug. You can not by code use it on a 30 amp circuit. Run a new circuit for the AC.