You have been driving to fast for two long or have just braked hard recently
Is your emergency break on? (Embarrassingly enough, this happened to me.) Incorrectly routed, adjusted(tensioned),...
that usually happens when you turn the heat on after it has not been in use for a long time
If you have forced air heat, the blower motor could be failing. You might need to have service man come...
Check from front to rear under the Jeep for anything touching the exhaust system. Also check all around the fan belt/s to see if a hose or cable/wire is touching the belt.