Lotus Elise S1 Service Notes page 449

Lotus Service Notes
Section PH
PH.1 - GENERAL DESCRIPTION
This section covers Elise and Exige models built in year 2000 fitted with air conditioning. For cars with a
heater alone, refer to section PF. For cars built prior to 2000 and fitted with a.c. alone (no heater) refer to
section PG.
Air Conditioning - Basic Principles
The air conditioning unit uses a cycling clutch system with a thermostatic expansion valve to provide
refrigerated air to the vehicle interior. The system comprises:
a closed circuit containing refrigerant R134a;
a compressor mounted on the front side of the engine, driven by multi-vee belt from the front end of the
crankshaft via an electromagnetic clutch;
a condenser mounted horizontally at the front of the car, beneath the engine cooling radiator;
a receiver-drier unit mounted on the right hand side of the radiator duct;
a thermostatic expansion valve fitted at the inlet connection to the evaporator;
an evaporator unit (cooler) fitted in the chassis well ahead of the cabin footwell.
Closed Circuit
The closed refrigerant circuit should not be opened unless absolutely necessary, and only then using
appropriate refrigeratant recovery equipment. Never allow the refrigerant to vent to atmosphere. Refer to sub-
section PH.5. Failure to observe these precautions may result in personal injury.
Compressor
When the engine is running, and the refrigeration controls demand it, the electromagnetic clutch incorpo-
rated in the compressor pulley is energised, which then locks the pulley to the shaft and drives.the compressor.
The rotary vane type compressor operates to discharge refrigerant vapour at high pressure and temperature
into the condenser. The compressor is lubricated by a quantity of special refrigerant oil, most of which is
retained in the compressor, with the remainder being circulated with the refrigerant. An integral thermal cut-out
switch is designed to prevent overheating damage by interrupting the compressor clutch circuit if an exces-
sively high temperature is detected.
In order to avoid engine stalling and to maintain idle speed when the additional load is placed on the
engine, a compressor engagement command is preceeded by a signal to the engine management E C M to
open the idle air control valve accordingly.
2000 / 04
Page 3