My parents have a 2000 s80 and when it got a new battery the ac and seat heater stopped working( they dont light up either), and the driver door lock is being kinda screwy, any help would be greatly appreciated.

 

Hmmm.. no professional advice yet huh.. Ok, I'll dive in.

Don't know if you done it already, but I would check and the fuses and relays. Especially those related to your problems. There are fuses under the hood. I also saw some in the left rear quarter panel, access them from the trunk.

If you don't find any suspects, I would remove the Negative cable from the battery. Let it sit for a little bit, then put it back. This way, hopefully things get reset. You might loose your stereo due to code issue, but that'san easy fix by looking for code from volvo or something.

Well, that's my unprofessional advice.