Hows the radiator overheating is it blowing coolant out? or steaming hot? Its possible the temperature gauge is not functioning. If it is blowing out under pressure that's from a bad head gasket! Regards
it could be a bad radiator cap just making a mess or if it really is over heating i would replace the temp sensor located just behind and between the ac and alternator since you stated it did not show it was hot. if the computer doesn't know its hot from the sensor its not going to turn on the electric cooling fan to cool it down which is another item you will want to check is working as well.
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