Is there a special extension cord for my window air conditioner?

Yes, you need to use a major appliance cord. A regular extension cord doesn't have heavy enough wire to safely conduct the necessary current.

Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.