2003 HONDA CIVIC fan

Catalytic Converter System
DTC Troubleshooting
DTC P0420: Catalytic System Efficiency
Below Threshold
NOTE: lf some of the DTCS listed below are stored at
the same time as DTC P0420, troubleshoot those DTCS
first, then recheck for DTC P0420.
P0137, P0138: Secondary Heated Oxygen Sensor(secondary HO2S) (Sensor 2)
P0141: Secondary HO2S (Sensor 2) heater
1. Reset the ECM {see page 1'l-4}, then continue to
step 2 through 5 to reset the readiness code.
2. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) untilthe radiator fan comes on.
Drive for about l0 minutes without stopping. Your
speeo can vary.
With the transmission in 4th gear, drive at a steady
speed between 50 62 mph (80-'100 km/h) for
30 seconds.
Repeat step 4 three times. Between each repetition,
close the throttle completely for 1 2 seconds. lf
the engine is stopped during this part of the
procedure, repeat steps 3, 4 and 5.
Check for a Temporary DTC with the scan tool.
Does the scan tool indicate Temporaty DTC
P0420?
YES Check the TWC. lf necessary, replace the
TWC.I
NO Check for readiness code completion. lfthe
readiness is complete, it was a interminent failure,
and the system is OK at this time. lf the readiness
code is incomplete, repeat steps 2 through 5.1
4.
11-167

PCV System
DTC Troubleshooting
DTC P1505: PCV Air Leakage
1. Reset the ECM (see page 11-4).
2. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) until the radiator fan comes on
3. Let the engine idle tor al least 40 seconds with the
throttle fully closed.
4. Check for a DTC P1505 with the scan tool
ls DTC P1505 indicated?
YES-Check these parts for vacuum leaks l
. PCV valve. PCV hose. EVAP canister purge valve
. Throttle body. Brake booster hose
NO - Intermittent failure, system is OK at this
time.l
11-168

Steering Column Inspection
. Check the steering column ball bearing(A) andthesteeringjointbearings(B)forplayandpropermovement. lfanybearing is noisy or has excessive play, replace the steering column as an assembly,'Checktheabsorbingplates(C),absorbingplateguides(D),stop(E),andcoatingplates(F) for distortion andbreakage. lf there is distortion or breakage, replace the steering column as an assembly.
17-11

21-2
z t-'5
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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 Conditioning
Component Location Index (cont'dl
CONDENSER FANTest, page 22-51
RADIATOR FAN RELAYTest, page 22-51
Tesl, page 22-51CLUTCH RELAY
MOTOR RELAYTest, page 22-5I
UNDER.HOOD FUSE/RELAY BOX
... A/C PRESSURE SWITCH
RADIATOR FAN
\
.\
-
'-t t_]]l
/l I T I --::--
l- -l -
CONOENSER FAN
21-4

Heating and Air Conditioning
General Troubleshooting Information
How to Retrieve a DTC
The heater control panel has a self-diagnosis function. To run the self-diagnosis function, do the following:
1. Turn the fan switch OFF.
2. Pressand holdthe recirculation control switch andthe rear window defoooer switch down.
3. Turn the ignition switch oN {lli.
4. Release both switches. The recirculation indicator and the rear window defogger indicator come on. The
recirculation indicator goes off 3 seconds later and the Ay'C indicator comes on. then the self-diagnosis will begin.
About 10 seconds later, the self-diagnosis will finish and the A,/C indicator goes off.
.lfanytroubleisfound.therecirculationindicatorblinksthediagnostictroublecode(DTC)toindicateafaulty
circuil or comDonent.. lf the system is OK, the recirculation indicator stays off.
atc
@r
RECIRCULATIONCONTROL SWITCH
BECIRCULATIONINDICATOB
/A\
-:@
INOICATOR
REAR WINDOWOEFOGGER INDICATOR
REAR WINDOWDEFOGGER SWITCH
Examole of DTC indication Pattern IDTC 7)
DTC 7
Reseiting the Selt-diagnosis Function
Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnosis
function aoain to make sure thatthere are no other malfunctions.
Recirculation +indicatot
Recirculation +indicalorgo6s oft----->
21-8

Heating and Air Conditioning
{
a
a
SvmptomDiagnostic procedureAlso check for
Recirculation control doors do not
change between Fresh and Recirculate
Recirculation Control Motor
Circuit Troubleshooting (see page
21 251
Cleanliness and tightness of all
connectors
Both heater and Ay'C do not workHeater Control Power and Ground
Circuits Troubleshooting (see
page 21-27)
Blown fuse No. '14 (10A) in the
under-dash fuse/relay box
Poor ground at G501
Cleanliness and tightness of all
conneclors
Condenser fan does not run at all (but
radiator fan runs with the Ay'C on)
Condenser Fan Circuit
Troubleshooting {see page 21-28)
. Poor ground at G301. Cleanliness and tightness of all
connectors
Both fans do not run with the A,/C onRadiator and Condenser Fans
Common Circuit Troubleshooting
(see page 21-29)
Blown fuse No. 1 (20A) and No.4
(20A) in the under-hood fuse/relay
box
Poor ground at G30l
Cleanliness and tightness of all
connectors
Compressor clutch does not engage(both fans run with A,/C on)
Compressor Clutch Circuit
Troubleshootinq (see Daqe 21-30)
Cleanliness and tightness of all
connectors
A/C system does not come on (both
fans and compressor)
Ay'C Pressure Switch Circuit
Troubleshooting (see page 21-32)
Blown fuse No. 1 (20A) and No. 4
(20A) in the under-hood fuse/relay
box
Poor ground at G301
Cleanliness and tightness of all
connectors
\Symptom Troubleshooting Index
\
21-10
!

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