One of the problems I have been fighting trying to get cars to pass HC is when the car is being tested is at least 180 degrees it's enough of a difference between passing & failing if the operator doesn't use his cooling fan & allows the car to get good & warm. Request that he doesn't use it. Of course this also depends if the car is set up properly for the test & no other problems exist. Also be sure its entered in the system as a GN not a Regal. The H.C. standards are more liberal for a GN . 110 ppm vs 70 for a Regal.