journalctl size
File size greater than 256M (change as needed on your system, see man find)
sudo find /var -size +256M -ls
pamac systemd timer running to manage the number of packages in cache (default is 3)
systemctl list-timers
Should see:
…pamac-cleancache.timer pamac-cleancache.service
To reduce the number see /etc/pamac.conf, KeepNumPackages. Can be run manually too. Search forum it comes up a lot (example).