scope:

Note: Nothing in the specification supersedes applicable laws and regulations unless specific exemption has been obtained.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose.

To define subsystem level noise measurements of HVAC blowers, stepper motors and DC motors that are used in heater modules or front and rear air condition modules. This procedure is used to gain knowledge of the N&V behavior of a blower module at the subsystem level before prototype vehicles are available. The measurements made on bare blower modules are comparable to in-car HVAC system measurements except for the effect of cavity resonances on the absolute noise level when measured in vehicle.

Foreword.

The noise emission of the HVAC module subsystem must be recorded to apply the objective methods for Sound Quality Metric evaluation. This subsystem has multiple modes of operation. Each mode of operation must be recorded independently for analysis. This procedure describes the operating conditions of the HVAC module subsystem, the appropriate sound recording methods for those operating conditions, and the analysis methods necessary for objective Sound Quality Metric evaluation.

Because blower noise emission is dependent on blower airflow rate, airflow measurements are a necessary part of an objective assessment of blower noise. Airflow rate is especially important when evaluating multiple blowers. Blower noise levels from multiple blowers can be compared by relating blower noise levels to airflow rates.

Applicability.

This procedure is appropriate for blowers on all kind of heating and air condition modules. It is also applicable for all kind of flap adjustment noises, such as, recirculation flaps, temperature flaps, ventilation flaps, foot room flaps, defrost flaps, or rear vent flaps whether they are driven by a DC or a stepper motor.