System: heater; defroster; defogger; ventilation. Equipment description: heating, ventilation and airconditioning (hvac) systems used in ambulances and emergency vehicles. Note: if your vehicle IS presented to an authorized dealer on an agreed upon service date and the remedy IS not provided free of charge within a reasonable time, please contact acc at 1-903-677-3161. Also contact the national highway traffic safety administration's auto safety hotline at 1-800-424-9393.