Ford F-550 Owner's Manual page 20

Instrument Cluster
If the gauge is operating in the Yellow or Red area, stop the vehicle and
verify the airflow is not restricted such as snow or debris blocking airflow
through the grill. If the gauge continues to show high temperatures, see
your authorized dealer.
20
2007 F-250/350/450/550 (f23)
Owners Guide (post-2002-fmt)
USA (fus)