Practical Approach for Vehicle HVAC Noise Reduction and Comfort Improvement

Comfortable cabin environment from temperature, noise and vibration point of view is one of the most desirable aspects of any vehicle operating in hot or cold environment. Noise generated from HVAC system is one of the most irritating phenomena resulting in customer dissatisfaction and complaints. It becomes absolutely necessary to have low HVAC noise levels when the target market has hot weather all round the year. Balance between control of temperature in desired way with least possible noise and vibration is the key for HVAC performance optimization within constrains posed by design and cost.

This paper describes the approach for NVH refinement of front HVAC system proposed for a vehicle with limited off-road capability for which packaging constraints and late changes related to airflow and HVAC unit design for meeting comfort and crash requirements resulted in deterioration of noise and vibrations while operation. The work includes on vehicle noise and vibration study, HVAC system noise source identification and ranking, study of noise transfer functions between on bench and vehicle, effect of various design parameters and components on noise, noise reduction trials and conclusions. Pre and Post refinement HVAC noise & airflow performance graphs are presented to justify relevance of work.