seat heater

For some reason the seat heaters are not working now and I am sure that they were working just the other day. neither side is working. So what should I look for, fuse? Or something else? I tried listening for the relay switch on both sides and couldn't hear anything...

2002 jetta

Update- tonight the drivers seat seemed to start working. I don't know why for sure but I did read something about going with the outside temperature or something don't know if that's true but the passenger seat didn't seem to work so I'm not sure what's going on with this I've been searching but haven't found anything very conclusive yet. Also I'm not sure if this is one of those bad wire intermittent problems or what but just might have to see. But in the mean time any other suggestions or experience with this problem would be helpful