Cadillac 2003 CTS Owner's Manual page 179

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Engine Coolant Hot Idle Engine
This message will appear when the engine coolant
temperature is too hot. Stop and allow the vehicle to idle
until it cools down.
NOTICE:
If the Engine Coolant Hot
appears on the DIC display, stop the vehicle as
soon as possible. Do not increase the engine speed
above normal idling speed. Severe engine damage
can result from driving a vehicle with an
overheated engine. See "Engine Overheating" in
the Index for more information.
This symbol appears
with the Engine Coolant
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Hot Idle Engine message.
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Idle Engine message
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Engine Coolant Hot AC (Air Conditioning) Off
This message displays when the engine coolant becomes
hotter than the normal operating temperature. To avoid
added strain on a hot engine, the air conditioning
compressor is automatically turned off. When the
coolant temperature returns to normal, the air
conditioning compressor will turn back on. You can
continue to drive your vehicle.
If this message continues to appear, have the system
repaired as soon as possible to avoid compressor
damage.
This symbol appears
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with the Engine Hot AC
Off message.
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