Replacing the fan relay in a 2005 Legacy is a relatively simple process that can be completed in about 30 minutes. The fan relay is responsible for turning the cooling fan on and off, so a faulty relay can lead to overheating or engine damage. Symptoms of a bad fan relay include the cooling fan not turning on when the engine is hot, the fan running constantly, or the fan not turning off when the engine is turned off.
To replace the fan relay, you will need a new relay, a 10mm socket wrench, and a Phillips head screwdriver. First, locate the fan relay. It is usually located in the fuse box under the hood. Once you have located the relay, disconnect the negative battery terminal. Then, use the socket wrench to remove the bolt that holds the relay in place. Finally, use the screwdriver to remove the relay from its socket. To install the new relay, simply insert it into the socket and tighten the bolt. Finally, reconnect the negative battery terminal and start the engine to test the new relay.