In addition to the dimensional concept, seat design and ergonomic properties of a car, interior climate control also contributes to the safety and comfort of its passen-gers. That’s why Mercedes-Benz is fitting all new A-Class models as standard with a powerful air conditioning system, whose user-friendly controls are located on the centre console. The driver and front passenger can use the rotary-type switches to adjust the temperature, air distribution and blower speed. The controls for the air conditioning are joined here by other climate-related buttons, such as those for the air recirculation function and heated rear windscreen.

A sensor located in the climate control unit monitors the temperature of the interior and ensures that the level programmed in by the vehicle occupants remains constant. Further sensors measuring the outside temperature and air humidity allow the air conditioning system (with fully adjustable coolant compressor) to be adjusted when required and therefore to economical effect. A solenoid valve enables the system to be regulated continuously in response to the level of humidity in the air, vary-ing the swept volume of the climate control compressor and thus the cooling effect.

Like every Mercedes air conditioning unit, the system in the new A-Class works according to the reheat principle. The system remains constantly active – in low as well as high outside temperatures – in order to first cool the intake air and at the same time remove the moisture from it with the aim of preventing the windows from misting up. The air is then re-heated to the desired temperature. A humidity sensor allows this reheat function to respond to need – the intake air is cooled according to the level of moisture it contains, and then re-heated.

Another special feature is the tunnel function. If the driver presses the air recirculation button down for an extended time (approx. two to three seconds), the air recircu-lation flap in the climate control unit and all the open side windows and sun-roof are closed automatically. When the button is pressed again, they all return to their previous positions.

Mercedes-Benz fits the CDI models as standard with a newly developed PTC (Positive Temperature Coefficient) heating system, which is positioned behind the air conditioning unit’s heat exchanger and activated automatically according to the outside temperature. The compact but powerful heating system whirrs into action a short time after the engine has been switched on, warming up the interior.

THERMOTRONIC automatic climate control with sun and pollutant sensor

THERMOTRONIC is a synonym at Mercedes-Benz for unbeatable climatic comfort and now also available for the A-Class. The highly efficient automatic climate control sys-tem is making its debut on the Mercedes compact car’s options list.

The THERMOTRONIC control unit differs from the air conditioning system in various ways. Its two striking rotary-type switches, for example, govern the blower speed and air distribution. In between these controls are push buttons, which are used to activate the residual engine heat utilisation function (right) and automatic mode (left). The driver and front passenger can key in their desired temperatures separately at the touch of a button in the centre of the control unit. Separate displays con-firm the values entered.

In the same way as the air conditioning system, THERMOTRONIC also works partly on the basis of data supplied by sensors indicating the interior and outside temperature and the level of humidity of the in-flow air. In addition, a pollutant sensor is also integrated into the system. If the concentration of nitrogen oxide and carbon monox-ide in the outside air exceeds certain values, THERMOTRONIC switches automatically to air recirculation mode. Seven electric motors in the THERMOTRONIC control unit ensure that the air flaps are controlled automatically.

The automatic climate control system also contains a special sun sensor. Positioned on the instrument panel, it supplies the THERMOTRONIC system’s electronic control unit with information on the intensity of the sun’s rays. In automatic mode, this sensor helps to control the quantity and temperature of the air channelled towards the driver and front passenger according to the angle of the sun’s penetration.

The air recirculation function also works automatically. In high outside temperatures, the microcomputer automatically adjusts the proportion of recirculated air in the in-flow air in order to cool the interior more quickly and to limit the energy required. Another standard feature of THERMOTRONIC is a combined filter with active charcoal layer, which collects dust particles and pollen when the air conditioning is set in fresh-air mode.

Four pivoting rectangular vents in the instrument panel, four defroster vents for the windscreen and side windows and four vents in the front and rear-passenger foot-wells ensure that the interior receives efficient ventilation. In conjunction with THERMOTRONC automatic climate control, Mercedes-Benz also equips the new A-Class with a vent which faces upwards from the centre of the instrument panel, distributing air over a large surface area and therefore not creating a draught, as well as two pivoting vents for the rear compartment positioned on the back end of the tunnel trim.

Audio systems: state-of-the-art technology from luxury-class models

In the area of entertainment and communications technology, systems more familiar from Mercedes’ leading models are now available for the A-Class. Topping the range is the optionally available control and display system COMAND APS, which combines the services of a radio, navigation system and DVD /CD player. The centrepoint of the system is the large (6.5-inch) TFT colour display boasting flawless clarity and colour presentation. A DVD is available for the navigation system featuring both the European road network and tourist destinations. The route guidance function uses a colour map on the COMAND display, arrow commands in the instrument cluster’s central display and audible instructions. Once the route has been calculated, the navigation DVD can be removed and replaced by music CDs. If the driver chooses this option, the navigation system relies on arrow commands only. The system is equipped with an FM-RDS dual tuner for receiving long, medium and short-wave radio stations.

The optional Audio 50 APS is a high-quality system which includes an FM dual tuner receiver, CD drive and arrow-based navigation system with integral RDS-TMC dynamic route guidance. The system’s display unit comes in the form of a 4.9-inch TFT colour screen with graphics reproduction capability. The navigation CD contains the road networks of all major European countries, and the CD drive can also be used to play music CDs whilst the route guidance function is in operation.

The Audio 20 CD radio is equipped with an FM /MW and LW receiver. Up to ten stations can be stored for each wave band. The system’s four-channel amplifier has output of 4 x 25 watts. The integral CD player can also play privately burned CDs. Automatic station search, the Radio Data System (in conjunction with FM reception) and scan function are further features of this optionally available system, whose integral telephone keypad can also function as a control centre for a mobile phone.

The entry-level system for the new A-Class is the Audio 5 CD (optional) with FM/MW/LW and SW receiver and CD player.

All Mercedes radios are linked up to the standard-fitted multifunction steering wheel to deliver faultless ease of use. A whole host of functions can be operated from here, allowing drivers to keep their hands on the steering wheel when adjusting the volume, for example, or , searching for a different radio station. Another outstanding feature of the audio systems is their speed-sensitive volume control. From approx 20 km/h the volume level is increased in stages in order to adjust to the changing driving situation. Aerial diversity, which selects the strongest signals picked up by the roof-mounted aerial and a pair of FM aerials in the rear window, thus ensuring optimum reception, is another impressive feature of the Audio 20 CD, Audio 50 APS and COMAND APS.

Flawless sound reproduction from the ten-speaker surround sound system

The Mercedes radios are hooked up as standard to six speakers. However, an even higher-quality eight-speaker set can be ordered as an option. Meanwhile, the newly developed surround-sound system (optional) with ten speakers, including active tweeter and woofer system with built-in amplifiers, takes sound reproduction to the next level and adapts precisely to the acoustics of the A-Class interior. A microphone assesses ambient noise conditions, allowing the microcomputer to adjust the volume and sound development of the system sensitively to the situation in hand. The result is a wonderfully consistent audio quality at all times. The sound system can be com-bined with the Audio 20 CD, Audio 50 APS and COMAND APS options. And customers can also specify a CD changer for six CDs as an option for the Audio 20 CD, Audio 50 APS and COMAND APS and this unit slots neatly into the glove compart-ment of the new A-Class.