808 / 1428
838
HVAC
Operation:
Whenever the engine is operating, the pulley is rotating
since it is connected to the crankshaft by a belt, but
the compressor does not operate until the clutch is
energized. When the air conditioning system is
switched ON, the ECU generates a signal for
energizing the compressor. The electromagnet attracts
the pressure plate and pulls the plate against the friction
facings on the pulley. The friction between the facing
and plate causes the clutch assembly to rotate as a
unit, and drive the compressor.
COMPONENT DESCRIPTION OF HVAC /
A/C SYSTEM :
Compressor
It is the heart of A/C system specially designed to
compress the refrigerant. The compressor draws
vaporized refrigerant from the evaporator. It compresses
the refrigerant (resulting into temperature rise of
refrigerant) and the refrigerant will be passed onto
condenser for condensation.
Compressor relay
Compressor relay is located in fuse box which is used
to operate the compressor magnetic clutch. The
magnetic clutch continues to operate as long as air
conditioner is under operation. Once the air conditioner
is put in OFF condition, the compressor relay gets
cut off and the magnetic clutch gets disengaged from
the compressor. The cut - in and cut - off of relay is
governed by ECU.
Magnetic clutch
A magnetic clutch is used to connect and disconnect
the compressor from the engine.
Main components are stator, rotor, and pressure plate.
Principle:
When the current is fed to the coil (as shown fig. on
the right), magnetic force is generated in iron II which
attracts iron I.
Construction:
A magnetic clutch consists of a stator, rotor with
pulley, and pressure plate to engage the drive pulley
and compressor magnetically. The stator is fixed on
the compressor housing, and the pressure plate is
attached to the compressor shaft. Two ball bearings
are used between the inner surface of the rotor and
the front housing of the compressor.