meta-gsj/recipes-phosphor/fans/phosphor-pid-control/fan-reboot-control.service

[Unit]
Description=Set Fan to Default Duty as Rebooting
DefaultDependencies=no
After=shutdown.target

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/usr/bin/fan-default-speed.sh

[Install]
WantedBy=shutdown.target