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FATC
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8. FATC UNIT
The front HVAC unit comprises of the following parts:
A. BLOWER
The Blower is located on the right top side of the
HVAC unit when viewed from inside the car. It acts
as a centrifugal pump drawing in air from the center
and pushing it out diagonally. The air flows through
the evaporator and the heater coil and then to the
cabin.
The Blower speed is control by blower control mod-
ule.
SPECIFICATION : BLOWER MOTOR
MODEL
HYOSUNG
VOLTAGE
DC 12.5 V
CURRENT
25A 10% MAX
RATING TORQUE
0.56 Nm @12.5 V
RATING SPEED
3800 300 rpm
RATING OUTPUT
313 W MAX
AIR FLOW
545 M3/HR
CLAMPING
TORQUE (FLANGE
NUT)
TBD N.m
B. EVAPORATOR COIL AND TXV
(THERMAL
EXPANSION VALVE)
EVAPORATOR COIL
It is a heat exchanger cum dehumidifier, which
absorbs heat and moisture of the air passing through
it to give cold dehumidified air. As the refrigerant
absorbs the heat it changes its state from liquid to
vapour. A thermistor (
temperature sensor)
is used to
measure the temperature of the air passing over the
evaporator in order to avoid freezing.
TXV (
THERMAL EXPANSION VALVE
)
The TXV used is block type valve. It consists of a
two passages one for refrigerant flowing into the
evaporator and the other for refrigerant coming out of
evaporator and into the compressor. A temperature
sensing element is placed in the outlet passage. This
sensing element is filled with a fluid which expands
and contracts when there is rise or fall in the
temperature. When the temperature of the refrigerant
flowing out of the evaporator rises it causes the
expansion of the refrigerant in the sensing element
which in turn pushes the pin, such that the ball valve
blocking the orifice opens to allow more refrigerant
into the evaporator. The pressure spring provided
below the ball tends to close the ball valve and
hence this pressure has to be overcome in order to
open the valve.
There is a passage in the block valve where
refrigerant flowing out can build pressure under a
diaphragm on which the sensing element is mounted
causing the diaphragm to move up; this provides the
needed pressure correction while regulating the
refrigerant into the evaporator.