Automatic Climate Control
87 - Air Conditioning - Automatic Climate Control (Optional)
NOTE: The sun sensor on the dashboard and the interior temperature sensor must not be covered, as this may impair the automatic climate control functions.
Functions
This air conditioning system controls the interior temperature preselected on the control panel completely automatically. The desired interior temperature can be set between 61 °F. (16 °C) and 85 °F. (29.5 °C). It is generally recommended to set the interior temperature to approx. 72 °F. (22 °C).
The system detects operating and ambient conditions of relevance to the interior climate via sensors and CAN. Automatic control is carried out primarily by way of the interior temperature sensor, the exterior temperature sensor and the solar radiation energy as detected by a sun sensor. This information is processed in the control unit (control panel) and converted into output signals for temperature control, the air distribution flaps (temperature and air distribution flaps are DC drive motors with position feedback), the fan and the compressor.
In addition to automatic climate control, the control panel also enables manual selection of the desired system status at any time. Changes regarding:
- temperature
- air flow rate
- air distribution
can be carried out by way of the control panel.
The cooling output of the air conditioning system is generated by a volume controlled swash plate (adjustable) compressor. Demand dependent metering of the refrigerant delivery rate helps to save energy, while continuous power consumption of the compressor helps to optimize idle speed.
Operation (automatic climate control panel)
The air conditioning system is operated by way of a control panel (a/c controls) with integrated control unit in the center console. The control panel differs visually from that on the previous Boxster (986) models because of the addition of a new control interface.
NOTE:
- On vehicles with the Sport Chrono Plus package, individual settings on the automatic climate control panel the can be stored on your personal vehicle key.
- See the section "Individual memory" in the separate PCM manual.
The main changes to the control panel are:
- Integration of the interior temperature sensors (previously in the dashboard on the passenger's side)
- Integration of the switches for heating the driver's and passenger's seats (previously in the center console).
- Integration of the button for heating the rear window (previously located beside the operating unit)
- Introduction of switches for adjusting the temperature and fan power (higher setting = switch up, lower setting = switch down).
- "ECO" marking (ECOnomy mode) on the button for switching the air conditioning compressor on and off (snowflake symbol on display goes on/off accordingly).
As a result of these changes, all of the heating functions in the vehicle are now together in a single unit.
Control Panel
Information is displayed by means of an LCD display and signalling lights (LEDs) in some buttons. When "LO" or "HI" appear on the display of the a/c control unit, this indicates that the system is operating at maximum cooling or heating power (the temperature control function is deactivated). "LO" and "HI" are displayed by the nominal temperature value segments.
"OFF" on the display indicates that the fan is off.
A - Seat Heating on/off
The seat heating settings can be adjusted individually for the left (button A) and right (button G) side. Apart from OFF level, two heating levels can be selected. When the appropriate button is pressed, the air conditioning control unit (control panel) transmits the altered button status (pressed 1x or 2x) to the vehicle electrical system control unit. The vehicle electrical system control unit controls the heating elements in the seat directly (heating-up phase) and reports the relevant heat status (setting 2 or setting 1) back to the control panel. This heating status is indicated to the user via the LED in the seat heating button.
NOTE: On the interior temperature (CAN signal) rising above 104 °F. (40 °C), the vehicle electrical system control unit switches off the seat heating. The button status is stored in the control unit, causing the seat heating to be reactivated when the temperature drops below 104 °F. (40 °C).
The operating time during the heating up phase is based on the interior temperature (CAN signal) according to the selected heat setting:
- Level 2 (at 104 °F. (40 °C) to <- 4 °F. (-20 °C) from 2.2 to a maximum of 11.0 minutes
- Level 1 (at 104 °F. (40 °C) to <- 4 °F. (-20 °C) heats from 0.5 to a maximum of 9.2 minutes
After the heating up phase the control unit switches to the continuous heating phase. The vehicle electrical system control unit now reduces the heating power of level 2 to 40 % and level 1 to 14 %.
B - Windshield
The defrost function can be activated immediately in all operating modes. On activation of this function, the temperature is switched to "HI", the air flow rate is increased and the air is distributed primarily towards the windscreen. ECO mode is additionally ended, if the intake temperature conditions (fresh air intake temperature sensor > 37 °F. (3 °C) permits. If the compressor cannot be activated, recirculation air mode will be started.
C - Recirculation Mode
NOTE: The air throughput is influenced by the back pressure which arises in the area of the fresh air inlet according to the vehicle speed. In order to compensate for this dependency, the distributor flap for fresh air/recirculated air (back pressure flap) is moved in the direction of "closed" (recirculated air) according to the vehicle speed (from 56 mph/90 km/h). The flap setting is also dependent on the fan voltage.
1 - Mode of functioning of manual recirculation mode
The fresh/recirculated air distributor flap can be activated at any time to prevent odour nuisance. However, recirculation mode is limited to max. 3 minutes when the air conditioning compressor is switched off (ECOnomy mode).
2 - Mode of functioning of automatic recirculation mode
At exterior temperatures of > 79 °F. (26 °C), recirculation mode is selected automatically by the program after a ventilation time of 30 seconds in order to accelerate the cooling-down phase - with the air conditioning switched on.
E - ECO Button (air conditioning compressor off/on)
The ECO button enables the selection of ECOnomy mode, which functions without the a/c compressor. ECOnomy mode permits cooling to values down to the exterior temperature.
F - Defrost Rear Window/Door Mirrors
NOTE: If the outside temperature is > 77 °F. (25 °C) (CAN signal), the heating time is just 10 seconds.
The heated rear window button in the control panel generates an electrical impulse, which is sent to the vehicle electrical system control unit via CAN. Once the vehicle electrical system control unit has activated the heated rear window relay (in relay holder 2), it sends the switch on status of the heated rear window back to the air conditioning control panel. The LED in the button on the control panel is then activated. The ON status of the heated rear window on the CAN bus causes the two door control units (in parallel with the window heating) to directly control the heating elements for the defrost function of the door mirrors. The maximum heating time for the rear window and door mirrors is 15 minutes.
I - Automatic Mode
Air distribution is controlled automatically. In addition to the state variable "Energy Requirement Level" (see section "Actuators and sensors"), the program also evaluates the outside temperature and engine temperature in order to take due account of cold start conditions and possible icing of the windows. Automatic mode is confirmed by the word "AUTO" on the display.
M - Manual Fan Adjustment
NOTE: The temperature indication on the display of the a/c control panel is switched between °C and °F by way of the on-board computer in the instrument cluster. (This switchover is not adopted by the PCM and must be carried out directly in the PCM if required. See also the section on electrics under "PCM").
In addition to automatic control, the fan output can also be adjusted manually by way of the rocker switches. The current air flow rate is indicated by a 19-bar indicator on the display.
Pressing the rocker switch up increases the fan output. Pressing the rocker switch down reduces the fan output down to a minimum of zero bars on the display. After releasing the switch and then pressing it down again, the fan is switched off (OFF mode). "OFF" appears on the display. When the fan is switched off, a compressor shutdown function protects the evaporator from icing.
In fan OFF mode, air distribution is set to defrost (defrost/footwell distributor flap) and recirculation (fresh/recirc. air distributor flap) and all other actuators are shut down.