There are a couple of diferent ways to find out if your air conditioning system is under warranty. Some of the air conditioning manufacturers have a website look-up tool, where you can type in your model and serial number of your unit to find out the status of your warranty. If a website tool is not available, a call to a local dealer or the manufacturer should do. Below are some links to some of the major manufacturer look-up tools.
Frigidaire- LinkTags: warranty