My 1998 catera's battery went dead one morning, and when I attempted to charge the battery back up overnight, it wouldn't fully charge. I noticed as it was charging, a quiet motor or fan was running behind the passenger dash, even though the car was turned off.

After some monitoring, I found out that if I warm the car up and then turn it off, 2 hours later this quiet fan starts up. This fan continues to run until the battery goes dead. To prevent this, I pull the #18 fuse out of the triangle shaped relay box next to the battery. This prevents that fan from starting up and prevent my battery from going dead.

So I took all this information to the dealer. They replaced the blower controller for $370 parts and labor, but 2 hours after I turned the car off, that stupid fan started again. I took it back to the dealer, and this time around the replaced the battery. They said mine wasn't holding a charge well, and that weak batteries can sometimes cause things to turn on in the car, even when the car is turned off. This didn't work either.

So has anyone here seen anything like this or encountered similar problems? I'd like to sell the car soon, but I can't tell the next buyer they need to pop the hood and pull this fuse if they plan to park for more than 2 hours. I need it fixed, but the dealer isn't much help.