2003 HONDA CIVIC Heating

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 Conditioning
Gircuit Diagram
UNDEN rcODFUSVRELIYSOXUNOER DASNfUSE/8EIlYBOX|GNUION SWTCfilG2 HoI ii 0l\l llll
+. C}F BLK/RED rG2 /
II
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I
In.G301
A/C PnESSUEtswTOt
t...iCF
RADIATOS
oT0n
NADIATOS) tAl'// swtlcllj 19S"F 193"C) l
CONDEN$N
MOTOB
I8u(
I
IBLX
I
G301
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;
/ .I IHEFMAI
Y PBorEcro8
lTl *n*,*,| _l
MUITIPLD(CONTFOIUNITI
-!10. irgF 8Ll
TT
BLU
I ilntho undor dasi luse/lelay box
21-14

Heating and Air Conditioning
DTC Troubleshooting
DTC 7: An Open in the Air Mix Control Motor
Circuit
1. Test the air mix control motor {see page 2'l-341.
ls the air mix control motor OK?
YES-Go to step 2.
NO-Replace the air mix control motor.l
2. Disconnect the air mix control motor 5P connector.
3. Disconnect heater control panel connectors A {14P)
and B (22P).
4. Check for continuity between the following
terminals of heater control panel connectors A
(14P) and B (22P) and the air mix control motor 5P
connector,
14P: 5P:
No. 1 No.5
No.2 No.4
No.3 No.2
No.9 No. 1
22P: 5P:
No.6 No.3
Wire side ol lem.letehi.6ls
ls there continuity?
YES-Check for loose wires or poor connections at
heater control oanel connectors A (14P) and B (22P)
and at the air mix control motor 5P connector. lf the
connections are good. substitute a known-good air
mix control motor, and recheck, lf the symptom/
indication goes away, replace the original air mix
control motor. lf the symptom/indication continues,
substitute a known-good heater control panel, and
recheck. lf the symptom/indication goes away,
replace the original heater control panel.l
NO Repair any open inthewire(s) ketweenthe
heater control panel and the air mix control
motor.l
21-16
DTC 8: A Short in the Air Mix Control Motor
Circuit
1. Test the air mix control motor(see page 21-341.
ls the ait mix control motor OK?
YES-Go to step 2.
NO-Replace the air mix contorol motor.I
2. Disconnect the air mix control motor 5P connector.
3. Disconnect heater control panel connectors A (14P)
and B (22P).
4. Check for continuity between body ground and
heater control panel connector A (14P) terminals
No. 1, 2, 3, and 9 individually, and between body
ground and heater control panel connector B (22P)
terminal No. 6.
HEATERCONTROL PANEL CONNECTOR A {I4PI
HEATER CONTFOL PANELCONNECTOR B I22P1
ls therc continuity?
YES-Repair any shortto body ground ln the
wire(s) between the heater control panel and the air
mix control motor.l
NO-Go to step 5.
Wire side of female terminals
Wire side oilema e lerminals

Heating and Air Conditioning
DTC Troubleshooting.(cont'd)
DTC 10: An Open or Short in the Mode
Control Motor Circuit
1. Test the mode control motor (see page 21-35).
ls the mode cottol motor OK?
YES Go to step 2.
NO Replace the mode control motor.I
Disconnect the mode control motor 10P connector.
Disconnect heater control panel connectors A (14P)
and B \22P1.
Check for continuity between body ground and
heater control panel connector A (14P) terminals
No. 2, 10, and 11 individually, and between body
ground and heater control panel connector B (22P)
terminals No. '17, 18, 19, and 20 individually.
HEATER CONTROL PANEL CONNECTOR A {14PI
2.
3.
Wire side ol lemale terminals
ls there continuity?
YES Repair any shortto body ground in the
wire(s) between the heater control panel and the
mode control motor.l
NO Go to step 5.
HEATER CONTROL PANELCONNECTOR B {22P)
Wire side of femaLe lerminals
21-18
5. Turn the ignition switch ON (ll), and check the same
terminals for voltage.
HEATEB CONTROL PANEL CONNECTOR A {14P)
Wire side of female terminal
HEATER CONTROL PANEL CONNECTOR B {22PI
35X6
tl1215T61118t92A2122
RED/YELWHT
Wire side of female terminals
ls there any voltage?
YES-. Repair any short to power in the wire(s)
between the heater control panel and the mode
control motor. This short may also damage the
heater control panel. Repair the short to power
before replacing the heater control panel.l
NO- Go to step 6.

Heating and Air Gonditioning
DTC Troubleshooting {cont'd)
DTC 12: A Problem in the Blower Motor
Circuit
'1. Check the No. 12 (40A)fuse inthe under-hood
fuse/relay box, and the No. 14 (10A) fuse in the
under-dash f use/relay box.
Are the tuses OK?
YES-Go to step 2.
NO Replace the fuse(s), and recheck.l
2. Connect the No. 2 terminal of the blower motor 2P
connector to body ground with a jumper wire.
BLOWER MOTOB 2P CONNECTOR
JUMPER ] BLU/BLK
Wire side ol female terminals
3. Turn the ignition switch ON (ll).
Does the blowet motor run?
YES Go to step 4,
NO Go to step 17.
4. Turn the ignition switch OFF.
5. Disconnect the jumper wire.
6. Disconnect the power transistor 4P connector.
21-20
8.
7. Check for continuity between the No. 3 terminal of
the power transistor 4P connector and body ground.
POWER TRANSISTOR 4P CONNECTOR
Wire side ol temale terminals
ls there continuity?
YES-Go to step 8.
NO-Check for an open in the wire between the
power transistor and body ground. lf the wire is OK,
check for poor ground at G502.I
Connect the No. 1 and No. 3 terminals of the power
transistor 4P connector with a jumper wire.
POWER TRANSISTOR 4P CONNECTOR
Wire side of female terminals
Turn the ignition switch ON (ll).
Does the blower motor tun at high speed?
YES-Go to step 10.
NO-Repair open in the wire between the power
transistor and the blower motor.l
Turn the ignition switch OFF.
Disconnect lhe jumper wire.
9.
10.
11.
2
34
BLK
o

Heating and Air Conditioning
DTC Troubleshooting lcont'd)
22. Measure the voltage between the No. 3 terminal of
the blower motor relay 4P socket and body ground.
BLOWER MOTOR RELAY 4P SOCKET
21
43
23.
ls there battety voltage?
YES-Go to step 23.
NO Replace the under-hood fuse/relay box.t
Turn the ignition switch ON {ll).
Measure the voltage between the No. 2 terminal of
the blower motor relay 4P socket and body ground,
BLOWER MOTOR RELAY 4P SOCKET
ls there battery voltage?
YES-Go to step 25.
NO Repair open in the wire between the No. 14
fuse in the under-dash fuse/relay box and the
blower motor relay.I
21-22
25.
26.
Turn the ignition switch OFF,
Check for continuity between the No. 1 terminal of
the blower motor relay 4P socket and body ground.
BLOWER MOTOR RELAY 4P SOCKET
ls there continuity?
YES-Repair open in the BLUIr'/HT wire between
the blower motor relay and the blower motor.l
NO Check for an open in the wire between the
blower motor relay and body ground. lf the wire is
OK, check for poor ground at G301.1\

Heating and Air Gonditioning
\
DTC Troubleshooting {cont'd)
6. Check for continuity between the No. 2 terminal of
heater control panel connector A (14P) and the
No, 2 terminal of the evaporalor temperature
sensor 2P connector.
HEATER CONTROL PANEL CONNECTOR A {14PIWire side of female terminals
LT GRN
EVAFORATOR TEMPERATURE SENSOR 2P CONNECTORWire side of female terminals
ls there continuity?
YES-Check for loose wires or Door connections at
heater control panel connector A ('l4P) and B l22Pl
and at the evaporator temperature sensor 2P
connector. lf the connections are good, substitute a
known-good heater control panel, and recheck. lf
the symptom/indication goes away, replace the
original heater control panel.l
NO Reoair ooen in the wire between the heater
control panel and the evaporator temperature
sensor.I
21-24
4.
DTC 15: A Short in the Evaporator
Temperature Sensor Circuit
1. Remove the evaporator temperature sensor (see
page 21-37).
2. Test the evaporator temperature sensor (see page
21-37 J.
ls the resistance within the specifications shown
on the graph?
YES Go to step 3.
NO Replace the evaporator temperature
sensor. !
Disconnect heater control panel connector B l22Pl.
Check for continuity between the No. 7 terminal of
heater control panel connector B {22P) and body
ground.
HEATER CONTROL PANEL CONNECTOR B (22P)
Wire side of female terminals
ls there continuity?
YES Repair short to body ground in the wire
betvveen the heater control panel and the
evaporator temperature sensor. I
NO-Substitute a known-good heater control panel,
and recheck. lf the symptom/indication goes away,
replace the original heater control panel.I

Heating and Air Conditioning
Recirculation Control Motor Circuit Troubleshooting (cont'd!
10. Turn the ignition swirch OFF.
11. Check for continuity between the following
terminals of heater control panel connector A ( 14P)
and the recirculation control motor 5P connector.'l4Pt 5P:
No.5 No. 1
No.6 No.2
HEATER CONTROL PANEL CONNECTOR A {14P}Wire side ol temale terminats
RECIRCULATION CONTROL MOTOR 5P CONNECTORWire side ol lemale terminals
ls there continuity?
YES Check for loose wires or poor connections at
heater control panel connector A ( 14P) and at the
recirculation control motor 5P conneclor. lf the
connections are good, substitute a known-good
heater control panel, and recheck. lf the symptom/
indication goes away, replace the original heater
control panel,I
NO Repair any open in the wire{s) between the
heater control panel and the recirculation control
motor.l
21-26