AUTOMATIC AIR CONDITIONING SYSTEM

Variations in the external temperature and the vehicle's speed are among the causes of temperature change inside the passenger compartment; the automatic air conditioning system installed on the 164 LS and 164 Q, controlled by an electronic control unit, maintains the temperature steady which in turn ensures that the desired environmental conditions are met.

The system is basically made up of several sensors which send out signals corresponding to the measured variables to the electronic control unit; the control unit processes these signals and sends them to the actuators which allows the internal temperature to be kept constant at the desired level.

The cooling is achieved through a suitable cooling circuit containing the new ecological gas R134a without CFCs as a coolant.

The R134a gas can not be mixed with the FREON 12 used in the systems on previous vehicles, so
DO NOT USE FREON 12
on the 164 MY94 vehicles.

The sealed air conditioning circuit is made up of a compressor activated by the crankshaft through an electromagnetic coupling, an evaporator and a condenser.

Suitable mechanical vents allow hot and cold air to be mixed,originating from the two systems, and the distribution of this in the passenger compartment.

A dedicated logic controls the movement of a vent, known as the "recirculation vent": this allows the same air taken from the passenger compartment to be re-used, which makes it quicker to reach the pre-established temperature or to avoid the inlet of particularly polluted air, in certain driving conditions. The electric fan can vary its speed within a very wide range.

View of the heater and air conditioning unit and the aeration ducts À

CONTROL FUNCTIONS

The automatic air conditioning system's functions for the 164 LS and 164 may be selected using the pushbuttons on the control unit; the control unit also contains pushbuttons which activate other functions not strictly connected with the air conditioning system (eg. fuel cap, boot opening, etc.) which will also be listed below.

1.  EXTERNAL AIR TEMPERATURE INDICATOR                 12. AUTOMATIC FUNCTIONING CONTROL BUTTON LUMINOUS
2.  REQUESTED AIR TEMPERATURE                              INDICATOR
3.  SYSTEM FUNCTIONING IN AUTOMATIC                    13. AIR RECIRCULATION CONTROL BUTTON WITH LUMINOUS
4.  INTERNAL TEMPERATURE DECREASE CONTROL BUTTON           INDICATOR
5.  INTERNAL TEMPERATURE INCREASE CONTROL BUTTON       14. DEFROSTING CONTROL BUTTON WITH LUMINOUS INDICA-
6.  COMPRESSOR DISACTIVATION CONTROL BUTTON WITH           TOR
    LUMINOUS INDICATOR                                 15. HEATED REAR WINDOW CONTROL BUTTON WITH LUMI-
7.  AIR DISTRIBUTION CONTROL BUTTON WITH LUMINOUS          NOUS INDICATOR
    INDICATOR                                          16. SYSTEM EXCLUSION CONTROL BUTTON
8.  AIR DISTRIBUTION CONTROL BUTTON WITH LUMINOUS      17. FAN SPEED DECREASE CONTROL BUTTON
    INDICATOR                                          18. FAN SPEED INCREASE CONTROL BUTTON
9.  AIR DISTRIBUTION CONTROL BUTTON WITH LUMINOUS      19. SYSTEM IN MANUAL FUNCTIONING INDICATOR
    INDICATOR                                          20. ELECTRIC FAN SPEED INDICATOR
10. AIR DISTRIBUTION CONTROL BUTTON WITH LUMINOUS      21. AIR DISTRIBUTION MANUAL SELECTION INDICATOR
    INDICATOR                                          22. CLOCK
11. AIR DISTRIBUTION CONTROL BUTTON WITH LUMINOUS      23. FAN SPEED MANUAL SELECTION INDICATOR
    INDICATOR

Automatic heating-ventilation system control unit

Compressor disengaging key ECON (6)

Pressing the ECON pushbutton disengages the compressor and positions the recirculation flap to intake air from outside. The system continues in automatic using outside air and the heater to bring the temperature inside the passenger compartment to the desired level. The recirculation function can also be set manually. The ECON function can be disabled by pressing the AUTO pushbutton which sets the system in automatic mode once again. (see also AIR RECIRCULATION KEY).

Automatic operating key (12)

Pressing the AUTO pushbutton, the system automatically regulates the temperature togetherwith all the system, ventilation and distribution functions and, if necessary, air recirculation on the basis of the settemperature and the information regarding the conditons sent to the control unit by the sensors.

The electronic control unit memorizes the last function chosen relative to air distribution and ventilation; if the engine stops for any reason with the air conditioning system in AUTO or with another user requested function, the system will return to the least pre-selected function when the engine is re-started.

Internal temperature regulation keys (4 and 5)

Pressing the TEMP+ AND TEMP- pushbuttons, the temperature set on the display is altered by one bar each time the pushbutton is pressed. The temperature range goes from l7oC (63oF) to 27oC (81 oF) and the extremes are marked with the letters LO (low) and HI (high). Selecting an extreme temperature, displayed with the letters LO, automatically sets the air conditioning system to maximum cooling and maximum fan speed (air to front air vents).

Selecting an extreme temperature, displayed with the letters HI automatically sets the air conditioning system to maximum heating and maximum fan speed (air to defrost).

Fan speed regulation pushbuttons (17 and 18)

Pressing AIR+ and AIR- increases or decreases the fan speed without varying the temperature control which remains in automatic mode; when one of the fan speed regulation pushbuttons is pressed the automatic operating key AUTO (28) is turned off and the fan speed manual selection indicatorcomes on (5). Pressing the AIR+ pushbutton increases the fan speed and the AIR- pushbutton decreases fan speed; each time the pushbuttons are pressed the bar on the display will be increased or decreased by one. If the AIR+ or AIR- pushbuttons are kept pressed down the fan speed will continue to increase or decrease. The fan speed manual selection function is disabled by pressing the AUTO pushbutton.

Air recirculation pushbutton (13)

Pressing this pushbutton enables the RECIRCULATION function. The control unit sends a command to the flap so that the air to be mixed is taken directly from the passenger compartment and the compressor is enabled. When the recirculation function is enabled, the compressor will remain enabled even if the ECON key is pressed. When the recirculation function is enabled the compressor remains enabled as long as the internal temperature is greater than l OoC (50oF).

NOTE: The compressor is only enabled or remains enabled if:

the external temperature detected by the sensors is higher than -5oC (41 oF);
consensus from demisting thermostat;
consensus from trinary (Q20 - thermostat on 3 levels).

The temperature control remains in automatic and the function can be disabled by pressing the same pushbutton again or by pressing the AUTO pushbutton.

Defrosting pushbutton (14)

Pressing the DEF pushbutton enables the defrost function. The control unit opens the mixed air distribution drum as wide as it will go (135oa) and maintains the following conditions for five seconds:

increase in fan speed;
increase in air temperature with respect to the level set;
air flow directed towards rear window only;
rear heated screen enabled (this function can be disabled by pressing the necessary pushbutton);
compressor enabled (in function with external temperature).

Enabling this function turns off the automatic system operation indicator (3) and turns on the warning lights of the functions that have been enabled.

The temperature control remains in automatic and the function can be disabled, before the set limit of five minutes, by pressing the same pushbutton again or by pressing the AUTO pushbutton; the return to the AUTO condition is managed gradually by reducing the air capacity and temperature and maintaining the distribution to defrost until the conditions prior to the DEF pushbutton being enabled are reached again.

Air distribution pushbutton on windscreen (11 )

By pressing this pushbutton the control unit directs the air flow entirely towards the windscreen; the temperature check remains in automatic and the function can be disabled by pressing the same pushbutton again or by pressing the AUTO pushbutton.

Air distribution pushbutton (10)

By pressing this pushbutton, the control unit directs the air flow in part downwards and in part towards the windscreen; the temperature control remains in automatic and the function can be disenabled by pressing the same pushbutton again or by pressing the AUTO pushbutton.

Air distribution pushbutton (9)

By pressing this pushbutton, the control unit directs the air flow completely downwards; the temperature control remains in automatic and the function can be disabled by pressing that button again or the AUTO pushbutton.

Air distribution pushbutton (8)

By pressing this button the control unit directs the air in part towards the central air vents and in part downwards; the temperature control remains in automatic and the function can be disabled by pressing the same pushbutton again or by pressing the AUTO pushbutton.

Air distribution pushbutton (7)

By pressing this pushbutton, the control unit directs the air flow completely towards the central air vents; the temperature control remains in automatic and the function can be disabled by pressing the same button again or by pressing the AUTO function.

Rear heated window pushbutton (15)

By pressing this pushbutton, the rear window demisting function is enabled for 20 minutes. Each time the function is re-enabled, by pressing the pushbutton, it will remain active for a further 10 minutes. It should be remembered that the function can only be re-enabled after the first session has ended; otherwise pressing this pushbutton will disable the function.

System off key (16)

Pressing the OFF pushbutton will disable the air conditioning system and no outside air whatsoever will be admitted into the vehicle; this function can be disabled by pressing the same pushbutton again or by pressing the AUTO pushbutton.

NOTE: The AUTO automatic operatlon Indlcator (3) Is swltched off when one of the air distribution (7, 8, 9,10 and 11 ) or fan speed control pushbuttons (AIR+ or AiR-) are activated and the selected indicator comes on; in all these conditions the system endeavours to malntaln steady the temperature set by the user.