2003 HONDA CIVIC Workshop Manual

Heating and Air Conditioning
Gircuit Diagram
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21-15

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

5. Turn the ignition switch ON (ll), and check the same
terminals for voltage.
HEATER CONTROL PANEL CONNECTOR A {14PI
HEATER CONTROL PANEL CONNECTOR B I22PI
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 air mix
control motor. This short may also damage the
heater control panel. Repair the short to power
before replacing the heater control panel.l
NO 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.I
Wire side of female terminals
DTC 9: A Problem in the Air Mix Control
Linkage, Door, or Motor
1, Test the air mix control motor (see page 21-34).
ls the air mix control motor OK?
YES-Substitute a known-good heater control
panel, and recheck. lf the symptom/indication goes
away, replace the original heater control panel.l
NO-Replace the air mix control motor, or repair
the linkage and door.l
21-17

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
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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.

Turn the ignition switch OFF, and check for
continuity between the following terminals of
heater control panel connectors A (14P) and B (22P)
and the mode control motor 10P connector.
14P: 10P:
No. 2 No. '10
No. 10 No, 1
No. 11 No.2
22P: 10P:
No. 17 No.8
No. 18 No.6,9
No. 19 No.5
No. 20 No. 4,7
HEATER CONTROL PANEL CONNECTOR A (14PIWire side of lemale terminals
HEATER CONTROL PANEL CONNECTOR B {22PIWire side of female terminals
ls there continuity?
YES-Check for loose wires or poor connections at
heater control panel connectors A (14P) and B (22P),
and at the mode control motor 10P connector. lf the
connections are good, substitute a known-good
mode control motor, and recheck. lf the symptom/
indication goes away. replace the original mode
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 in the wire(s) between the
heater control Danel and the mode control motor.l
MODE CONTROL MOTOR lOP CONNECTORWire side of female terminals
DTC 11: A Problem in the Mode Control
Linkage, Doors, or Motor
1. Testthe mode control motor (see page 21-35).
ls the mode control motor OK?
YES Substitute a known-good heater control
panel, and recheck. lf the symptom/indication goes
away, replace the original heater control panel.l
NO Replace the mode control motor, or repair the
linkage and doors.l
21-19

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

1a
13.
Disconnect heater control panel connector A (14P).
Check for continuity between the No. 7 and No. 8
terminals of heater control panel connector A (14P)
and body ground individually.
HEATER CONTNOL PANEL CONNECTOR A {14PI
ls there continuity?
YES Repair any shortto body ground in the
wire(s) between the heater control panel and the
power transistor.I
NO Go to step 14,
Check for continuity between the following
terminals of heater control panel connector A ( 14P)
and power transistor 4P connector.'l4Pt 4P:
No.7 No.4
No.8 No.2
HEATER CONTROL PANEL CONNECTOR A (14P)Wire side ot female terminals
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ILU/YEL
POWER TRANSISTOR 4P CONNECTORWire side of female terminals
ls thete continuity?
YES Go to step 15.
NO Repair any open in the wire(s) between the
heater control panel and the power transistor.l
14.
BLU/YEL
15.
lo.
17.
18.
19.
Reconnect heater control panel connector A (14P).
Test the power transistor (see page 21-38).
ls the power transistor OK?
YES Check for loose wires or poor connections at
heater control panel connector A (14P) and at the
power transistor 4P 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 Replace the power transistor.I
Disconnect the jumper wire.
Disconnect the blower motor 2P connector.
Measure the voltage between the No, 1 terminal of
the blower motor 2P connector and body ground.
BLOWER MOTOR 2P CONNECTOR
BLU/WHT
Wire side of female terminals
ls thete battery voltage?
YES- Replace the blower motor.l
NO Go to step 20.
Turn the ignition switch OFF.
Remove the blower motor relay from the under-
hood fuse/relay box, and test it (see page 22-511.
ls the relay OK?
YES Go to step 22.
NO- Replace the blower motor relay.l
20.
21.
(cont'd)
21-21