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Lotus Service Notes Section PN
Evaporator
The evaporator is a 'serpentine' type heat exchanger mounted within the HVAC unit. The low pressure liquid
refrigerant flowing into the evaporator via the expansion valve, begins to boil (evaporate) and in so doing, draws
the necessary heat for this process from the airstream passing across the evaporator finning. This airstream is
consequently cooled, and is directed through the various outlet vents to the passenger compartment.
When the a.c. switch is pressed by the driver, and other parameters allow it (i.e. ignition on, blower fan
speed selected, a.c. system pressurised, ambient temperature above 3°C), the a.c. circuit is activated and re-
frigerant flow established. A thermostat, using a thermistor positioned against the outlet side of the evaporator
finning, monitors the temperature of the refrigerated air and signals the ECU to regulate refrigerant flow in order
to provide an output air temperature just above that at which ice may form on the evaporator.
The inlet and outlet pipes connect to the evaporator via the expansion valve block, into which they are
sealed using 'O' rings and a clamp plate. The inlet is supplied from the receiver-drier, and the outlet feeds into
pipework routed through the body RH sill, to the compressor.
Ventilation
Air in the cabin is exhausted via an outlet vent at the left hand side of the rear bulkhead, and another at
the bottom right hand corner of the bulkhead. Ducting from each of these vents connects to the rear luggage
compartment, from which air escapes to atmosphere through two one-way flap valves fitted in the rear transom
and concealed by the rear bumper.
PN.2 - HEATER/A.C. AIRFLOW OVERVIEW
The HVAC unit comprises left and right hand plastic mouldings sandwiched together and containing a
pair of blower fans supplied from two intake sources, an a.c. evaporator, a heater matrix, and two electrically
controlled flaps; one for the fresh air intake and one for the heater matrix.
Outlet to screen vents
Outlet to face level vents
Air distribution unit
Outlet adaptor Duct to
passenger
footwell
Pollen lter
Distribution
drum actuator
Intake adaptor
Fan housing
Fixing to chassis
bulkhead
Fixing to subframe Refrigerant connections
crossmember
Temperature ap actuator
Fixing bracket to subframe p118
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