Can you describe it? If it's rusty, you might want to use lots of white vinegar, let set, and blot with thick towels, several times. I wouldn't let it set longer than 10 minutes before blotting but if you do, and it dries, try vacuuming up any rust dust before you rewet.
You might try calling consumer hot line of the company which manufactures the air conditioner or call a repairman and see if you can't find out what liquid it is.Then google that for stain removal.
Login using the form on the top of the page to post feedback (if you are a registered user). If you have not yet registered, click here to do so. It's FREE!.
