Basic Air Conditioning System Function - GF83.00-P-9902A

Model All (4xWD) 

Model All (CAR) 

Overview 

This document contains information on:

• General 
• Function requirement 
• Function 
  • Maximum cooling 
  • Temperature control 
  • Maximum heating 
  • Drying 
  • Filter 
  • Versions 
  • Refrigerant 

General 

The purpose of the air conditioning system is to bring the air in an area to a certain state and keep it there ("conditioning").

The basic air conditioning system functions are:

• To change air temperature (by heating or cooling)
• To change air humidity (dry)
• To remove air components (filtering)
• Change in local air speed

The climate control is regulated by the climate control, control system.

Function requirement 

• Circuit 30t ON

Function 

Overview of climate control 

Courtesy of MERCEDES-BENZ USA

The outlet air temperature at the air vents is regulated using the air mixing flaps (2). They continuously regulate the air flow of warm air from the heater core (3) and, where applicable, cooled air from the evaporator (1). The climate control, control system uses the signals from the evaporator sensor and depending on the model involved, the signals from other temperature sensors to regulate the respective air vents.

The heater core (3) is generally connected to the cooling circuit of the vehicle drive motor.

The evaporator (1) is connected to the refrigerant circuit of the air conditioning system.

Maximum cooling 

Maximum cooling, function diagram 

Courtesy of MERCEDES-BENZ USA

At maximum cooling request, the fresh air or recirculated air drawn in by the blower motor flows through the evaporator (1). Then it flows - routed by the air mixing flaps (2) - past the heater core (3). The fresh or recirculated air then flows unheated or cooled to the respective air vents.

Temperature control 

Temperature control, function diagram 

Courtesy of MERCEDES-BENZ USA

The air mixing flaps (2) open more or less depending on the requested temperature. As the temperature requirement increases, more and more fresh air or recirculated air flows from the evaporator (1) through the heater core (3). The temperature controlled fresh air or recirculated air then flows to the respective air vents.

Maximum heating 

Maximum heating, function diagram 

Courtesy of MERCEDES-BENZ USA

At maximum heating request, the fresh air or recirculated air drawn in by the blower motor flows through the evaporator (1). It then flows, routed by the air mixing flaps (2), entirely through the heated heater core (3). The heated fresh air or recirculated air then flows to the respective air vents.

Drying 

Air drying takes place physically. The flowing air is first cooled in the air conditioner evaporator and can absorb less moisture as a result. This condenses and is guided out of the vehicle through the drain hose of the air conditioner. The air is then heated back to the required temperature level for the vehicle interior by the heater core. Through this procedure, the air reaches the desired temperature, but with less moisture.

Filter 

The fresh air is filtered through a dust prefilter during intake. Fresh air and recirculated air are also filtered through an activated-carbon coated filter in the air conditioner. Depending on the equipment, these filters can be replaced with filters that are of greater quality.

Versions 

Refrigerant 

Two different types of refrigerant are used:

• Synthetic refrigerant R134a
• Alternative synthetic refrigerant R1234yf

The refrigerant circuits for R134a and R1234yf are identical.