A cold test best localizes

Hyperalgesia  is  manifested  in endodontic pain patients when noxious stimuli (e.g., refrigerant  sprays  or  carbon  dioxide  snow  used  in  the  cold  test) produce much more pain than they would in teeth with normal pulp tissues. Spontaneous pain involves episodes of pain that seem to  be  unprovoked.  All these changes can be partly Explained by sensitization of peripheral nerve endings in the pulp. Cohen's Pathway of the Pulp ed:11th Pg551