1999 HONDA CIVIC pan

Heater
lllustrated Index
'96 - 98 Models ................................ 21'2
'99 - 00 Models ................................ 21'3
Circuit Diagram
'96 - 98 Models .....21-4
'99 - 00 Models ................................ 21-5
Troubleshooting - '96 - 98 Models
Symptom Chart ............................... 21-6
Heater Control Panel Input/
Output Signals ..............,.............. 21-7
Flowcharts
Blower Motor Speed ................... 21-8
Bf ower Motor ,...21'10
Mode Control Motor ............... ,.'.' 21-13
Recirculation control Motor ....... 21-16
Heater Control Panel ................ ... 21 -14
Troubleshooting - '99 - 00 Models
Symptom Chart ............................... 21-19
Seff-diagnosis Function ............,,,.... 21-20
Flowcharts
Air Mix Control Motor ......,.......... 21-21
Mode Control Motor ............... ..... 21 -25
Recirculation Control Motor ....... 21-27
Bf ower Motor Speed .............. .....21'29
Bf ower Motor ....21-31
Heater Control Panel ................,.. 21-35
Heater Control Panel Input/
Output Signals ............................. 21-36
Blower Unit
Repf acement .........21-37
Overhaul ................ 21-38
* Heater Unit
Replacement ....'....21-39
overhaul """" """' 21-4'l
Heater Control Panel
Repfacement .........21'42
Overhaul -'96 - 98 Models ........... 21-43
Temperature Control
Adjustment - '96 - 98 Models """" 21-44
Adiustment - '99 - 00 Models .......21-45
Air Mix Control Motor
Test - '99 - 00 Models ...........' .......21'46
Replacement - '99 - 00 Models ....21'46
Mode Control Motol
Test ................, .,...'.21'47
Replacement '.'."...21-47
Recirculation Control Motor
Test ................. .......21-48
Repf acement ......." 21-48
Relays
Test ................. .......2'l-49
Heater Fan Switch
Test - '96 - 98 Models ............. .......21-49
Mode Control Switch
Test -'96 - 98 Models ..........."....... 21-50
Power Transistor
Test - '99 - 00 Models ....'........ ....".21-50
*: Read SRS Drecautions before working in this area.

lllustrated Index
'96 - 98 Models
SRS components are located in this area. Review the SRS component locations, precautions, and procedures in the SRS
section {24) before performing repairs or service.
BLOWER UNITReplacement, page 21-37Overhaul, page 21-38
HEATER UNITBeplacement, page 21-39Overhaul, page 21-41BLOWERRESISTOBTest,
CONTROL MOTORTest, page 21-48Replacement, page 21'48
a/c swtTcH{wirh A/c)
MOO€MOTORTest, page 21 47Replacement, page 21'47
AIR MIX CONTROL CABLEAdjustment, page 2'1-44Replacement, page 21'43
HEATER FANswtTcHTest, page 2l'49
MODEHEATER CONTBOLPANELswrTcHEsTest, page 21 50Rgplacement, page 2'l-42Overhaul, page 21-43
TEMPERATURE CONTROLLEVERAdiustment, page 21 44
Detroster-aqtivated A/C System
Turning the defroster on activates the A,/C and sets the air flow mode to FRESH. lt is possible to turn the A,/C off or to
change the air flow to RECIRCULATE by pressing the A/C bunon or the FRESH/RECIRCULATE button.
21-2

'99 - 00 Models
UNDER,HOOO FUSE/RELAY 8OX
PUSN SWITCH
lHce nvosrar F)- aLu neo(Wirh IVC)
DASH LIGHTS -/1BBTGNTNESS < l- FEoCONTROLLER -!
IGN TION SW TCHUNDEF DASHFUSElRELAY BOX
**,',,* **",@ ",.
@f
u,n,",,
ELUAVHT
I
YBLUi BtK
BLOWERMOTOR
ELOWERMOTORHIGHRELAY
PNK/BLK
FED''WHT
RED,YEL
GRY
BRN
YEL
YEL/FEO
6RNiYEL
8LU/!VHT
YEL/BLU
BRNfiHT
GFNM/HT
GRNi FED
O :8P CONNECTOR
! :20P CONNECTOF
E : 12P CONNECToR
BLUi BLK
1
tic
HEATER CONTROL PANEL
VENT
MOOEHEAT CONTFOLMOTOF- M.COMDEF
[[f&H,,4*,",,
BLK

Heater Control Panel Input/Output Signals
HEATER CONTROL PANEL lilP CONNECToR
Wire side of lemale terminals
21-7
Terminal
No.
Wire
colorSignalTerminal
No.
Wire
colorSignal
1YELHEAT/DEFINPUT8YEVREDVENTINPUT
BLfiELINPUT9G RNI/ELHEATIr'ENTINPUT
WHT/BLU+BINPUT'10BLKGROUNDOUTPUT
4YEUBLUDEFINPUT11*BLU/REDA./C THERMOSTATINPUT
5REDDASH LIGHTS
BRIGHTNESS CONTROLLEROUTPUT12GRN/WHTFRESHINPUT
6RE D/8LKCOMBINATION LIGHT
SWITCHINPUT13GRN/REDRECIRCULATEINPUT
1BLUMHTHEATINPUT14GRNHEATER FAN SWITCHOUTPUT

Troubleshooting -'96 - 98 Models
Mode Control Motor lcont'dl
From page 2l-13HEATER CONTROL PANEL lilP CONNECTOR
Wire side of lemaie terminals
Check tor a short in the wi.e(s):1. Remove the center dashboardlower cover (see section 20),and disconnect the heater con-trol panel 14P connector.2. Check for continuity betweenthe No. 1, 4, 7, 8 and 9 termi-nals and body ground individ-
Raprir.ny short in the wire(s)betw€en the mode control motorand the heater control panel.
Check for a shon to power:
Check the same wires {or voltage.
Repair short to pow6r in thewiro(3) betwoen the mode con-lrol motor .nd tha heate. controlprnel, This short also damag.stho heater cont.ol prnel. Repailthe short to power b€{ore replac-ing the heeter conlrol pan6l.
ls there any voltage?
To page 21 15
21-14

From page 21-14
Check tor an open in the wire{s}:
Check for continuity between the
following terminals of the mode
control motor 7P connector and
the heater control Panel 14P con-
nector-7P: 14P:No.2 - No.4No.3 - No. 1No.4 - No.7No.5 - No.9No.6- No.8
Repair any opsn in the wirels)
bctwoan the mode control motor
and the hoator conlrol Panolls there continuitY?
Check Io. loo3. wires or Poorconnoctions at lhe hoat€r control
Danel 14P connactor, and 3t the
mod6 conilol motot 7P connec-
tor. It tho connoctions ara good.
rsDlaco the heat€r coilttol panel.
HEATER CONTROL PANEL 14P CONNECTOR
Wire side of {emale terminals
MODE CONTROL MOTOR 7P CONNECTOR
Wire side of female terminals
21-15

From page 21-16
ls there any voltage?
Check {or a short in the wire(s):1. Remove the center dashboardlower cover (see section 20),
and disconnect the heater con_
trol panel 14P connector'
2. Check for continuity between
the No. 12 and No. 13 termi-
nals and body ground individ-
Repair 5hort in the wire{sl between
the recirculation control motor and
the heater control Panel
Check Ior a short to Power:Check the same wires for voltage
Repair short to Power in the
wire {s) between the recirculationcontrol motor and the heater
control panel. This short also
damages the heater controlpanel. Repair the short to Powerbetore replacing the heater con-
trol panel.
Check lor an open in the wire(s):
Check for continuity between the
following terminals of the recircu
lation control motor 4P connector
and the heater control Panel 14P
4P. 14P:No.2 - No. 12No.4 No. 13
Repair open in the wirelsl
between the recirculation control
motor and the heater controlpanel.
ls there continuitY?
Check for loose wires or Poorconnections at the heater control
Danel 14P connector, and at the
recirculation control motor 4P
connector. lf the connections aregood, replace the heater control
Danel,
HEATER CONTROL PANEL 14P CONNECTOR
I;-?45
789'o lx11121314
GRN/WHT
0) (0
GRN/BED
Wire side of female terminals
GRN/RED
GRN/RED
RECIRCULATION CONTROL MOTOR
4P CONNECTOR
Wire side of female tetminals
I23i--?156
78I'olx11121314
GRN/WHT
V)(v
145
7IIrol\l rr1213
GRN/WHT
r zl/lt
21-17

Troubleshooting -'96 - 98 Models
Both heater and A/C do not work.
Check the No. 17 {7.5 A) fuse in theunderdash fuse/relay box, and theNo. 47 (7.5 A) fuse in the underhood fuse/relay box.
R.phce the fuso{s), .nd rccheck.
Chack tor an open in the wi.e:1. Remove the center dashboardlower cover (see section 20),and disconnect the heatercontrol panel 14P connector.2. Torn the ignition switch ON {ll).3. Measure the voltage betweenthe No. 2 terminal of theheater control panel 14P con-nector and body ground.
Rcpair opGn in th€ wiro betwoonthe No. 17 tuse and the hoatclcontrol panel.
ls there baftery voltage?
Check for an opon in the wiro:1. Turn the ignition switch OFF.2. Measure the voitage betweenthe No. 3 terminal of theheater control panel 14P con-nector and body ground.
Rgprii open in th6 wira b€twacnthe No. il7 tui. and the heat.tcont.ol p.nal.
ls there battery voltage?
Check foi an open in the wi.e:Check for continuity between theNo. 10 terminal ot the heater con-trol panel 14P connector andbody ground.
Check lor an opon in tho wireb€{w6on the hoator control oaneland body ground. lI the wirc isOK, check tor poor ground atG401 .nd G4O2.
Check for looae wiaos or ooolconnections at the hoater controlpanol 14P connector. lf the con-nactions dre good. 3ubstitute tknown-9ood heater controlpanel, and rech6ck. It tho symp-tom/indication 9oe3 .wry,replace the original heatel con-trol oanol.
Heater Control Panel
HEATER CONTROL PANEL 1,lP CONNECTOR
Wire side of female terminals
21-18