2003 HONDA CIVIC valve

ABS Components
System Description (cont'd)
ABS Modulator
The ABS modulator consists of the inlet solenoid valves, outlet solenoid valves, reservoir, pump, pump motor, and the
damping chamber. The modulator reduces the caliper fluid pressure directly. lt is a circulating-type modulator
becausethe brakefluidcirculatesthroughthecaliper,reservoir,andthemastercylinder.Thehydrauliccontrol has
three modes: pressure intensifying, pressure retaining, and pressure reducing. The hydraulic circuit is an independent
four-channeltype, one channel for each wheel.
Pressure intensifying mode: Inletvalve open, outlel valve closed
Master cylinder fluid is pumped out to the caliper.
Pressure retaining mode: lnlet valve closed, outlet valve closed
Caliper fluid is retained by the inlet valve and outlet valve.
Pressure reducing mode: Inlet valve closed, outlet valve open
Caliper fluid flows through the outlet valve to the reservoir.
lvlotor operation mode: When starting the pressure reducing mode, the pump motor is ON.
When stopping ABS operation, the pump motor is OFF.
The caliper fluid is pumped out by the pump, through the damping chamber, to the
master cvlinder.
19-40

t
Wheel Sensors
The wheel sensors are the magnetic contactless type. As the gear pulser teeth rotate past the wheel sensor's magnetic
coil, AC current is generated. The AC frequency changes in accordance with the wheel speed. The ABS control unit
detects the wheel sensor signal frequency and thereby detects the wheel speed.
!t LOW SPEED
Wheel Speed and Modulator Control
8E!EEETqE VEJ!q!ESPEEq
5
PRESSURE
OUTLETVALVE 9p
OFF
INLETVALVE oN
OFF
MoroR I-,. ltlOFF
When the wheel speed drops sharply below the vehicle speed, the inlet valve closes and il necessary, the outlet valve
opens momentarily to reduce the caliper fluid pressure. The pump motor starts at this time. As the wheel speed is
restored, and the outlet valve closes, the inlet valve opens momentarily to increase the caliper fluid pressure.
GEAR PULSERWHEEL S€NSOR.r HIGX SPEED
19-41

6. To remove a front drain valve (A)from the body,
remove the kick panel, left or right (see page 20-50).
Tie a string to the end of the drain tube, then pull
the front drain tube (B) down out of the front pillar.
To remove a rear drain valve (A) from the cargo
compartment, remove the rear side trim panel (see
page 20-51).Detach the clips (B), then remove the
drain tube (C),
B
1.
8. Installthe frame and drain tube in the reverse order
of removal, and note these items:
. Before installing the frame, clear the drain tubes
and drain valves using compressed air.. Check the frame seal.. Clean the surface ofthe frame.. When installing the frame, first attach the rear
hooks into the body holes.. Make sure the connectors are plugged in
properly.
. When connecting the drain tube, slide it overthe
frame nozzle at least 10 mm (0.39 in.)..Installthetubeclip(A) on the drain tube (B) as
shown.
Upward
t-
I
I
B
Check for water leaks. Let the water run freely from
a hose without a nozzle. Do not use a high-pressure
spray.
9.
20-43

21-2
z t-'5
z t-o
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21-8
21-9
21-10
21-11
21-14
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HVAC (Heating, Ventilation, and Air Gonditioningl
Heating and Air Conditioning
SpecialTools
Comoonent Location lndex ........
A/C Service Tios and
Precautions
A,/C Refrigerant Oil
ReDlacement
General Troubleshooting
lnformation
DTC Troubleshooting Index .......
Symptom Troubleshooting
1ndex..............
System Description .....................
Circuit Diagram
DTC Troubleshooting ..................
Recirculation Control Motor
CircuitTroubleshooting .......... 21-25
Heater Control Power and Ground
Circuits Troubleshooting ........ 21-27
Condenser Fan Circuit
Troubleshooting ...................... 21-28
Radiator and Condenser Fans
Common Circuit
Troubfeshooting ...................... 21-29
Compressor Clutch Circuit
Troubleshooting ...................... 21-30
A,/C Pressure Switch Circuit
Troubleshooting ...................... 21-32
Air Mix Control Motor
Test and Reolacement ............. 21-34
Mode Control Motor
Test and Replacement ............. 21-35
Recirculation Control Motor
Test and Reolacement ............. 21-36
Evaporator Temperature Sensor
Reolacement and Test ............. 21-31
Power Transistor Test ................. 21 -38
Heater Control Panel and
Push Switch Assemblv
Removal and Installation ........ 21-38
Dust and Pollen Filter
Reolacement ..21-39
Blower Unit Removal and
lnstallation ...... 21-39
Blower Unit Comoonents
ReDlacement ............................ 21-41
Evaporator Core
Reolacement ..21-42*Heater Unit/Core
ReDlacement ..21-43
Heater Valve Cable
Adjustment .....21-46
CompressorReplacement .......... 21-47
Comoressor Clutch Check .......... 21-48
Comoressor Clutch Overhaul ..... 21-49
Compressor Thermal Protector
Reo1acement ............................ 21-51
Comoressor Relief Valve
Reolacement ............................ 21-51
Condenser Reolacement ............ 21-52
Refrigerant Recovery .................. 21-53
System Evacuation ...................... 21-54
System CharginS ......................... 21-55
Refrigerant LeakTest .................. 21-56
A,/C Svstem Tests ........................ 21-57

Heating and Air Gonditioning
Component Location Index
SERVICE VALVE{LOW.PRESSUBE SIDEI
EVAPORATOR CORE(Built-in the heater unit)Beplacement, page 21 42
COMPRESSORBeplacement, page 21 47Clutch Check, page 21-48Clutch Overhaul, page 21-49Thermal Protector Check, page 21-48Thermal Protector Replacement, page 21 51Relief Valve Replacement, page 21 51
SERVICE VALVE{HIGH-PRESSURE SIDEI
RECEIVER/DRYER
CONOENSEBReplacement, page 21-52

HEATER UNIT/COREBeplacement, page 21-43
BLOWEN UNITRemoval and Installation, page 21-39
HEATER VALVE CABLEAdjustment, page 21-46
BLOWER UNIT COMPONENTSReplacement, page 21-41
DUSTAND POLLENFILTERReplacement, page 21'39
RECIRCULATION CONTROL MOTORTest, page 21-36Replacement, page 21-36
MODE CONTROL MOTORTest, page 21-35Replacement, page 21-35
AIR MIX CONTROL MOTORTest, page 21'34Replacement, page 21'34
POWER TRANSISTORTest, page 21-38
HEATER CONTROL PANELRemovaland Installation, page 21 38
PUSH SWITCH ASSEMBLYRemoval and Installation, page 21'38EVAPORATOR TEMPERATURESENSORReplacement, page 21-37Test, page 21-37
21-5

Heating and Air Gonditioning
System Description (cont'dl
The air conditioning system removes heat from the passenger compartment by circulating refrigerant through the
system as shown below.
/
BLOWER FAN
\
\,u
EXPANSION VALVE(Meters the requiredamount of refrigerantinto the evaporator)
A/C PRESSURE SWITCHWhen the refriqerant is below196 kPa (2.0 kgi/cm',28 psi)or above 3,140 kPa (32 kgf/cm'455 psi), the Py'c pressureswitch opens the circuit tothe Py'C switch and stops theair conditioning to protect thecompressor-
RECEIVER/DRYER(Traps debris, andremoves morsturel
APOBATOR TEMPERATURESENSOR
THERMAL PROTECTOR(Opens the compressor clutch circuitwhen the compressot temperaturebecomes too high)
RELIEF VALVE(Relieves pressure at the compressorwhen the pressure is too high)
A/C COMPRESSOR(Suction and comoression)\-^
I HrcH PRESSURE vAPoR
[ '.... -:--l Low PREsSUBE LrourD
tffi Low PREssURE vAPoR
This vehicle uses HFC-134a (R-'134a) refrigerant which does not contain ch lorofluorocarbons. Pay attention to the
following service items:
. Do not mix refrigerants CFC-12 (R-12) and HFC-134a (R-134a). They are notcompatible.. Use onlythe recommended polyalkyleneglycol (PAG ) refrigera nt oil (KElHlN SP '!0) designedfortheR-134a
compressor. Intermixing the recommended (PAG) refrigerant oil with any other retrigerant oil will result in
compressor failu re.. AllAy'C system parts (compressor, discharge line, suction line, evaporator, condenser, receiver/dryer. expansion
valve, O-rings for joints) have to be designed for refrigerant R 134a. Do not exchange with R-'12 parts.
. Use a halogen gas leak detector designed for refrigerant R-134a.. R-12 and R-134a refrigerant servicing equipment are not interchangeable. Use only a recovery/recycling/charging
station that is U.L.-listed and is certified to meet the requirements of SAE J2210 to service R-134a air conditioning
system.. Always recover the refrigerant R-134a with an approved recovery/recycling/charging station before disconnecting
any Ay'C fifting.
/-
CONDENSER(Radiation of heat)
21-12

Heating and Air Gonditioning
a
1.
Evaporator Core Replacement
Recover the refrigerant with a recovery/recycling/
charging station (see page 21-53).
Remove the bolt, then disconnect the suction line
(A) and the receiver line (B)from the evaporator
core.
6x10mm9.8 N.m (1.0 kgt.m, 7.2lbf.ft)
Remove the blower unit (see page 21-39).
Remove the self-tapping screws and the expansion
valve cover.
21-42
5. Carefully pull out the evaporator core without
bending the pipes.
Installthe core in the reverse order of removal, and
note these items.
. lfyou're installing a new evaporator core, add
refrigerant oil (KElHlN SP-]0) (see page 21-6).. Replace the O-rings with new ones at each fitting,
and apply a thin coat of refrigerant oil before
installing them. Be sure to use the correct O-rings
for HFC-134a (R-'134a) to avoid leakage.. lmmediatelyafter usingthe oil, reinstallthecap
on the container, and seal it to avoid moisture
absorotion.. Do not spill the refrigerant oil on the vehicle; it
may damage the paint. lf the refrigerant oil
contacts the paint, wash it off immediately.. Charge the system (see page 21-55).
6.