FWIW, there is a TSB which specificly address the problem of excessively warm air thru the vents. It only applies to the 00 & 01 X's and Frontiers. Have your dealer look up in the ASSIST for 2000 Xterra, Heater/AC section and excessive heat. Up pops a bulletin w/ part #'s for the new grille's. If your still under the 3 yr/36k miles warranty it's a Free fix.