2892639 - E6020 AIR CONDITIONING - Functional description (Automatic Air Conditioning, Euro 3)

Functional description

The climate control control unit M70 receives a supply controlled by the ignition (INT/A) at pin 12 of connector A from the line protected by fuse B27; the same line also supplies all the system actuators. The direct supply arrives from the battery (maxifuse J/B1 of B5) at pin8 of connector B through fuse F12 of the junction unit B1. The supply for illuminating the controls with the side lights on reaches the lights G45 from the line coming from the switch for the steering column switch unit H5 and is protected by fuse F3 of B1 . Pin 8 of connector A and pin 4 of connector B of M70 are earthed. Pin 2 of connector A signals the outside temperature to the instrument E50 . The sensor which measures the outside temperature is located on the external rear view mirror P60 : the sensor receives a 5 V supply from pin 7 of connector B of M70 and sends the signal to pin 6 of connector A. Control unit M70 is also connected to the treated air sensor K87 which receives a 5 V supply from pin 7 of connector B which sends a signal to pin 1 of connector B of M70 . The fan H81 and temperature H82 adjustment knobs receive a 5V supply and reference earth from the control unit - pins 9 and 7 of connector B - and return a potentiometric signal to pins 3 and 2 of connector B, respectively.

The controls for unit H80 contain:

• the switch for engaging the recirculation, supplied by the line controlled by the ignition INT/A, which sends a signal to pin 12 of connector B of M70 ;
• the passenger air temperature sensor, connected to pin 7 of connector A of M70 ; the fan motor is constantly supplied (line controlled by the ignition INT/A) so that the temperature measured is not affected by the stationary air under the dashboard.

Switch I65 controls the MAX DEF function sending a signal to pin 6 of connector B of M70 and to H80 (which inhibits the recirculation and engages the compressor). The air conditioning system is equipped with two actuators for recirculation ( N82 ) and air mixing ( N81 ). The recirculation actuator N82 is operated by the control unit M70 from pins 10 and 11 of connector A. The mixing actuator N81 is controlled by the control unit M70 from pins 14 and 15 of connector A, receiving a supply and earth for controlling the potentiometer from pins 7 and 9 of connector B and sending a feedback signal to pin 4 of connector A of M70 . The electronic governor M72 operates the fan at different speeds: it receives an input signal from the control unit (from pin 1 of connector A) and transforms it into a variable voltage signal that controls the fan. The supply for the governor is controlled by the ignition (INT/A) by fuse B27 ; it is connected to the earth for the control unit - pin 16 of connector A of M70 . The fan N85 is supplied directly from the battery from the maxifuse line of J/B1 of B5 protected by fuse F12 of B1 , whilst it is controlled at the different speeds for the voltage signal coming from the electronic governor M72 . The control unit M70 is equipped with a self-test system which can be used by connecting the unit to connector R10: it receives signals from pins 10 and 11 of connector B through diagnostic lines L and K. Pin 13 of connector A controls the engagement of the compressor, whilst the request signal reaches pin 5 of connector B (  See E6021  COMPRESSOR ENGAGEMENT ).