Climate Control
Overview
The climate control system is no longer a luxury item in modern vehicles. It has instead become a factor for active safety, and cannot be considered part of the safety equipment in the vehicle.
The correct temperature in the passenger compartment increases safety.
It is well documented that the human performance abilities are reduced in heat. Research carried out in traffic and in a normal vehicle demonstrated that when the passenger compartment temperature was increased from 21 to 27°C:
- the risk of the driver missing important traffic information (hazard warnings, traffic signals, signs etc.) increased by 50%
- the driver reaction times were 22% slower.
With an air conditioning system in the vehicle, car travel is both more comfortable and safer.
A climate control system provides increased comfort by:
- cooling the air in the event of high temperatures in the surrounding air or in warm, sunny conditions
- warming the air in the event of low temperatures
- dehumidifying the air
- filtering the air.
The relative humidity of the air is extremely important for our well-being. We perceive a relative humidity of 30-60% to be comfortable, as the moisture that is given off by the human body can easily be absorbed by the surrounding air.
If the humidity exceeds 75%, we perceive it to be oppressive and uncomfortable in warm weather, as the air cannot absorb much more moisture. For this reason, the climate control system is designed to regulate both temperature and air humidity.
The vehicle is equipped with either:
Electronic climate control, ECC
ECC is a fully automatic climate control system that has the option of manual settings.
Manual climate control, MCC
MCC is a manual climate control system.
The climate control system comprises a heater and an air conditioner. These are combined in the distribution housing to form a single unit with a shared ventilation system for distributing heating and cooling in the passenger compartment.
The system mixes the air, i.e. hot and cold air are mixed to achieve the desired temperature. One advantage of this is that the temperature in the passenger compartment can be changed quickly if required. Another advantage is that the ECC system compensates extremely quickly when the external conditions change.
The climate control module (CCM) controls the climate control system and the buttons in the dashboard environment panel.
The climate control system also includes a number of sensors.
Design
Blower fan
The fan wheel is the radial type with a guide vane rim on the outer edge. The fan wheel is balanced using steel clips.
The blower fan motor is a permanent magnet type fan.
The blower fan has stepless electronic control.
The power unit is mounted under the fan unit. The power unit can be removed.
Filter
The filter is located after the fan to also clean recirculated air. The filter is coded, that is, designed so that it cannot be installed incorrectly.
There are two types of filter.
- Particle filter
- Multi-filter.
The multi-filter filters particles in the same way as the particle filter. The multi-filter contains active carbon which reduces the influx of gases (bad odors) into the passenger compartment.
The multi-filter is only available for vehicles with electronic climate control (ECC) and then in combination with the air quality sensor (AQS).
NOTE: The climate control system has either a particle filter or a multi-filter, never both.
Heat exchanger
In order to heat the air in the passenger compartment, the heating system uses the heat that is generated by the engine. The heat exchanger is connected to the cooling system for the engine. The outlet connection for the heat exchanger is located directly on the engine at the point where the pressure and temperature of the coolant are highest. The coolant flows through the cooling ducts for the engine block and on into the heat exchanger. The return flow is connected to the return pipe on the suction side of the water pump.
The heat exchanger comprises a pipe loop through which the engine coolant flows. The pipe has flanges that provide heat to the airflow.
Engine coolant constantly flows through the heat exchanger. There is no valve to regulate the flow. The selected temperature is achieved using dampers for the right and left-hand sides of the car installed upstream of the heater element. These control the amount of air to be warmed. There is also a damper after the heater element which guides air out into the passenger compartment through the various vents.
Location of the components in the climate control system
1. Heat exchanger
2. Damper motor, temperature, left
3. Blower fan
4. Damper motor, fresh air intake and recirculation damper
5. Power unit for blower fan motor
6. Particle filter or multi-filter
7. Damper motor, ventilation and floor (also defroster for MCC)
8. Damper motor, temperature, right
9. Damper motor, defroster (only ECC)
10. Air quality sensor (AQS)
11. Evaporator temperature sensor.
Function
Blower fan
The blower fan provides the airflow through the vehicle.
The blower fan must be operating before the climate control system can be engaged.
The blower fan switches off when the vehicle speed is approximately 160 km/h.
Filter
The particle filter cleans the air of particles such as dust and pollen, which would otherwise pass through the air intake into the passenger compartment.
The multi-filter has the same function as the particle filter, but also neutralizes unpleasant smells and keeps the air as free from gases as possible. In vehicles that have the multi-filter, known as the air quality system (AQS), there is also an outside air sensor that ensures that the recirculation closes in the event that the content of gases in the outside air increases. This increases the service life of the multi-filter.