over heating on 2002 Cadillac DeVille DTS

over heats, but it happens qucker when the air conditioner is on.

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2 answers
over heats, but it happens quicker when the air conditioner is on
It could be many things, hard to comment without being able to do some basic diagnostic tests. Check the coolant level is OK, after that the most likely causes are a cooling system thermostat that is not fully opening, a partially restricted radiator,a mildly blown head gasket or cooling fan that is not operating correctly.