Climate Control System: Overview

Overview




The climate control system is no longer a luxury item in modern vehicles. It has instead become a factor for active safety, and can now 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 seven seat XC90 has an extra air conditioning unit in the rear. The additional air conditioning unit is located inside the panel on the left hand side of the cargo compartment panel.
The climate control module (CCM) controls the climate control system and the buttons in the dashboard environment panel. For further information, see Design and Function, climate control module (CCM).
The climate control system also includes a number of sensors. For further information, see Design and Function, climate control module (CCM).
Diesel vehicles have an additional heater (in some markets). The additional heater can be extended to a parking heater by the addition of a timer.
When the engine is running, the additional heater can provide extra heat to the passenger compartment and the engine. The parking heater heats up the passenger compartment and the engine when the engine is not running. This function can be started directly or by using a timer.
Gasoline cars may have an additional heater/parking heater as an option.