Your 1998 Cadillac Deville shows a coolant temperature of 220 when you are driving air cond is on what should this number be Is problem?

A coolant temperature of 220°F (104°C) in a 1998 Cadillac DeVille, especially with the air conditioning on, is too high. The normal operating temperature for most vehicles, including this model, is typically between 195°F and 220°F (90°C and 104°C), but closer to the lower end of that range. Reaching 220°F consistently, and especially with the AC on (which adds thermal load to the engine), suggests a problem.

Possible causes include:

* Low coolant level: Check your coolant reservoir. Low coolant means less effective heat transfer.

* Faulty thermostat: A stuck closed thermostat will prevent coolant from circulating properly, leading to overheating.

* Water pump failure: A malfunctioning water pump won't circulate coolant effectively.

* Radiator problems: A clogged radiator or a failing radiator fan will hinder heat dissipation.

* Faulty cooling fan: The cooling fan might not be turning on when needed, particularly with the AC on.

* Head gasket leak: A more serious issue, a head gasket leak can allow combustion gases to enter the coolant, causing overheating and potentially pressure buildup.

Do not ignore this. Continuing to drive with a consistently high coolant temperature risks serious engine damage. Have your vehicle inspected by a qualified mechanic as soon as possible to diagnose and repair the underlying problem. Driving with the engine running this hot can lead to warping the cylinder head, cracking the engine block, or causing other costly repairs.