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Lotus Evora. Manual - part 81

Lotus Service Notes

Section PN

Ambient air collected from the top of the intake duct, ahead of the engine radiator, is fed via an insulated

fibreform duct to a pollen filter mounted at the intake to the HVAC unit, within which the airflow is divided towards

the inner and outer sides of the two blower fans. Air enters the fan drums axially and is centrifuged outwards to

be directed into the evaporator chamber. A second intake duct collects air from the cabin interior via a central

aperture in the footwell toeboard, from which the air flows through a duct formed in the lower section of the

HVAC unit and into the fan chamber in a similar manner to the ambient flow. Electrical resistors used in the fan

speed circuitry are cooled by the incoming airflow stream. The fresh air intake may be closed off at the driver's

request by an electrically operated flap at the top of the unit, which closes or fully opens the ambient air intake.

The re-circulation intake is open at all times.

All air exiting the fan chamber is directed through the evaporator, whether or not a.c. is selected, and is then

divided between routes flowing either past, or through the heater matrix by an electrically operated air blender

flap, the position of which is determined by the temperature selector knob. Blended air then leaves the top rear

of the HVAC unit and enters the Air Distribution Unit (ADU) which passes beneath the base of the windscreen

and is secured to the top of the footwells. A part cylindrical rotary mask on a horizontal axis, controls the airflow

exiting the ADU into a top mounted port for the windscreen vents, an adjacent port for the face level vents, and,

via a port in each end plate of the mask, to outlets supplying a duct in the top of the passenger footwell, and

through the inboard side of the pedal box. The rotation of the mask is driven by a stepper motor (common with

the air intake and air blender actuators) mounted on the left hand side of the ADU.

Interior Climate Controls

The interior climate control panel is located on the centre console and consists of three rotary control

knobs, for air distribution, temperature and fan speed, and four button switches, for air conditioning, demist,

air re-circulation and heated rear screen. When the sidelamps are switched on, the rotary control graphics are

backlit white and red/blue by an electro-luminescent panel, with red lit pips in the knobs to indicate their position.

The button switches are backlit red with ignition or sidelamps switched on, and will light up brightly (HRS and

demist in amber) when activated. Press the switch a second time to switch off. Climate control functionality

requires the ignition to be on, and for refrigeration and heat production, the engine needs to be running.

Distribution Control

This rotary control is positioned at the top of the HVAC panel and allows a choice of air distribution from

the various outlet vents. There are 5 designated positions with corresponding symbols, although there is a

progressive transition from each airflow mode to the next, allowing a preferred balance to be attained.

Face level vents

To face level vent

ducting in underside

of fascia top panel

Air distribution unit

Airflow from

HVAC unit

Lotus Service Notes

Section PN

Face level vents & footwells

Footwell vents

Footwells & windscreen

To face level vent

ducting in underside

of fascia top panel

Airflow from

HVAC unit

To footwell vents

Airflow from

HVAC unit

To footwell vents

To windscreen vent ducting

in underside of fascia top panel

Airflow from

HVAC unit

To footwell vents

Lotus Service Notes

Section PN

Windscreen

Temperature Control

The rotary temperature control actuates the air blender flap, which dictates the proportion of the airflow

which is directed through the heater matrix. With the control knob fully clockwise at the coldest position, the

heater matrix is fully shut off. As the control is turned counterclockwise, the flap is moved to allow some airflow

through the heater matrix, until at the fully hot position, all airflow is directed through the matrix for maximum

heating.

Interior Fan

The lowermost of the rotary controls, allows the selection of 4 speeds for the interior fan, and functions

with the key at the accessory or ignition positions. Turned fully clockwise, the fan is switched off. Turning the

knob counterclockwise through 4 detent positions provides increasing fan speed and airflow delivery. Note that

the air conditioning will not function until a fan speed is manually selected.

Re-circulation Switch

This switch functions with the key at the accessory or ignition positions, and will maintain its status through-

out ignition cycles.

The re-circulation port in the footwell toe-board is open at all times, such that the greater proportion of air

drawn into the fan chamber, via a duct incorporated into the bottom of the HVAC housing, is always from the

cabin interior. The fresh air intake on the top of the unit is controlled by a stepper motor and flap valve, and is

normally open to provide approximately 30% fresh airflow. To close the intake and prevent fumes being drawn

into the cabin, or to provide the quickest response to temperature change requests, the fresh air intake may

be closed off by pressing the re-circ. switch, to result in 100% re-circulation. This option should, however, be

used sparingly to avoid stuffiness in the cockpit.

Air Conditioning Switch

The engine must be running for the a.c. to operate. This switch signals the engine ECU with an air condi-

tioning request, and will maintain its status throughout ignition cycles. The ECU determines whether the running

conditions allow for compressor activation. Conditions which will inhibit a.c. include:

near full throttle demand;

excessive coolant temperature;

any fault codes set;

low refrigerant pressure.

When appropriate, the ECU will activate the a.c. by applying a duty cycle to the compressor solenoid valve,

thus generating a swash plate angle and initiating refrigerant flow.

Demist Switch

In order to allow a single touch selection of demist/defrost settings, a dedicated switch is provided. The

switch is operative only with ignition on, and will default off at the next ignition cycle. When activated:

To windscreen vent ducting

in underside of fascia top panel

Airflow from

HVAC unit

Lotus Service Notes

Section PN

The interior fan will operate at full speed;

All airflow will be directed to the windscreen;

Air conditioning will be switched on (may be overridden by manual de-selection).

Note that an appropriate temperature setting must be selected manually.

Heated Rear Screen

Due to the heavy current demand, this switch will operate only when the engine is running. Under this

condition, the HRS and door mirror heating elements will be activated for a period of 10 minutes before auto-

matically switching off. The switch and heating cycle will default off next time the ignition is turned on.

Pollen Filter

Mounted at the air intake to the HVAC unit, is a folded paper element pollen filter which should be renewed

at intervals specified in the Maintenance Schedule. An access panel beneath the front body hatch is provided

to allow filter replacement by simply pulling out the old element and pressing in the new.

Engine Bay Ventilation

Various intake and outlet vents are provided in the rear body to allow ventilation and cooling of the engine

bay.

Intake vents ahead of the rear wheelarches provide ambient air for the engine air intake, and for engine

bay cooling.

Outlet grilles around the top of the tailgate panel exhaust hot air from around the catalytic converter at the

front of the engine bay.

An outlet grille at the base of the tailgate glass, and to either side, exhaust hot air from around the catalytic

converter at the rear of the engine bay.

PN.3 - COOLING FANS & RE-CIRCULATION PUMP

The two cooling fans are fitted on the top side of the radiator/condenser package, and the coolant re-

circulation pump is mounted at the LH side of the engine bay, beneath the air cleaner. Both the fans and pump

are controlled by the engine management ECU using data provided by the engine coolant temperature sensor

and the a.c. trinary switch mounted in the refrigerant line between receiver-drier and evaporator.

Cooling Fans

The cooling fans are switched as a pair, and will operate at half speed (connected in series) when cool-

ant temperature reaches 98°C on rise (94°C with a.c. on), and switch off at 96°C on fall (92°C with a.c. on). If

coolant temperature rises to 105°C (96°C with a.c. on), the fans will switch to full speed (connected in parallel),

reverting to half speed on fall at 98°C (94°C with a.c. on).

Note that the temperatures displayed on the instrument panel may differ from the programmed values

described above due to instrument damping lag.

The fans are also activated by signals received from the trinary switch; the fans will run at low speed for

pressures between 13 - 18 bar, and at high speed for pressures over 18 bar.

Certain types of ECU detected engine fault will also cause the fans to be activated as an engine protection

measure. If the ECU receives a coolant temperature sensor signal voltage outside of the acceptable range, a

default setting equating to 60°C will be substituted, and the cooling fans will run at half speed.

Engine bay front cooling Hot air

from around

exhaust

system

Engine air intake Hot air from front of engine bay

ohe31

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