NANO

HVAC

839

HVAC

(a) Condenser:

It is the heat exchanger where heat dissipation takes

place. It consists of aluminium tubes and series of

fins to provide the maximum heat transfer. Air flow

across the condenser is induced by vehicle movement

and assisted by electric fan attached to the frame of

the condenser. The high pressure refrigerant vapour

enters the condenser inlet. As the vapour passes

through the condenser tubes, the air flow, assisted by

the fan, carries the latent heat away from the

condenser. This induces a change of state resulting

in the refrigerant condensing into a high pressure warm

liquid. From the condenser, the refrigerant continues

to the receiver/ dryer.

(b) Integrated Receiver Dryer (IRD):

This component acts as a reservoir and is used to

hold extra refrigerant until it is needed by the

(a) Evaporator unit

It is the last component in the cycle and serves as

heat absorption unit. As the refrigerant flows through

the evaporator it picks up heat from the cabin and

gets vaporized. As this change of state occurs, a large

amount of latent heat is absorbed. The evaporator is

therefore cooled and as a result heat is extracted from

the air flowing across the evaporator. The refrigerant

leaves the evaporator, on its way to the compressor,

as a low pressure gas. An evaporator sensor

(thermistor) measures the air temperature at the

evaporator outlet and sends signal to engine ECU for

engaging/disengaging of compressor to prevent icing

of the evaporator.

(b) Expansion valve

This small valve controls the flow of refrigerant into the

evaporator. It is controlled by a temperature sensor at

the evaporator outlet. If the outlet temperature is too

high, it means not enough refrigerant is flowing into

the evaporator and poor passenger cooling will result.

If the outlet temperature is too cool, it means too much

refrigerant is flowing and the evaporator fins will

probably load up with ice. In either case, the feedback

temperature sensor opens or closes the expansion

valve opening to achieve the correct flow rate and

evaporator outlet temperature.

Condenser and Receiver Dryer (R.D.)

evaporator. The drier within the receiver unit contains

a filter and desiccant (drying material) which absorb

moisture and prevent desiccant dust from being

carried with the refrigerant into the system.

The receiver drier is integrated into the condenser and

is seperately serviceable.

Evaporator unit and Expansion valve