1999 HONDA CIVIC Ac thermostat

Troubleshooting
('99 00 models)
From page 22 18
Check lor an open in the wire:1. Turn the ignition switch OFF,then disconnect the ju mper
2. Disconnect the heater controlpanel 20P connector.3. Turn the ;gnition switch ON{

i.4. Measure the voltage betweenthe No. 11 terminal of theheater control panel 20P con-nector and body ground.
Ropai. opan in tho wira batwaonthe A/C thermostat and thehoater control oanol.ls there battery voltage?
Check the push switch:1. Turn the ignition switch OFF.2. Disconnect the push switch12P connector.3. Check for continuity betweenthe No. I and No. 10 terminalsof the push switch 12P con-nector with the A/C switch ON.
Check for loose wi.es or poor
connections el the hgater controlpanel 20P connector and pushswitch 12P connector and at theA/C thermostat 3P connector. Ittha connections are good, substi-tute a known-good heatea con-trol pan€|, and recheck. lf thesymptom/indication goe3 away,replace lhe original healer con-trol oan€|,
HEATER CONTROL PANEL anP CONNECTOR
Wire side of temale terminals
PUSH SW]TCH 12P CONNECTOR
Wire side of female terminals
,/1,/156
7819t01112
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A/C ThermostatRelays
Test
1.Remove the Ay'C thermostat (see page 22-29).
Connect baftery power to the No. 3 terminal, ground
the No. 2 terminal, and connect a test light between
the No. 1 and No. 3 terminals.
NOTEr Use a 12 V,3 W- l8 W test light.
Dip the IVC thermostat into a cup filled with ice water,
and check the test light.
Serp6ntine-type evaporator
The light should go off at 36 - 39'F {2 - 4"C} or less, and
should come on at 39 - 41"F (4 - 5"C) or more
Laminale-type evaporator
The light should go off at 39 - 43'F (4 - 6'C) or less, and
should come on at 43 - 45"F (6 - 7'C) or more
lf the light doesn't come on and go off as specified,
replace the PVC thermostat.
12V,3W-18W
Test
There should be continuity between the No, 1 and No.2
terminals when power and ground are connected to the
No.3 and No. 4 terminals, and there should be no conti-
nuitv when Dower is disconnected.
2
Condenser fan relay
Compressor clutch relay
a
a
,I Ib
In Io'r I
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t:n
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22-21

A/C System Service
Pressure Test Chart
NOTE: Performance Test is on page 22-24,
Test resultsRelated symptomsProbabl€ causeRemedy
Discharge (high)
pressure aDnor-
mally high
After stopping compressor. pres-
sure drops to about 200 kPa
{2.0 kgflcm,,28 psi) quickly, and
then falls gradually.
Air in systemRecover, evacuate, and
recharge with specified amount.
Evacuation: see page 22-45
Charging: see page 22-46
Reduced or no air flow through
condenser
. Clogged condenser fins. Condenser fan not work-
ing properly
Clean.
Check voltage and fan rpm.
Check fan direction.
Line to condenser is excessively
hot.
Restricted flow of refriger-
ant in system
Restricted lines
Discharge pres-
sure abnormally
High and low pressures are bal-
anced soon after stopping compres-
sor, Low side is higher than normal.
. Faulty compressor dis-
charge valve. Faulty compressor seal
Replace the compressor.
Outlet of expansion valve is not
frosted, low pressure gauge indi-
cales vacuum.
. Faulty expansion valve. Moisture in system
. Replace,. Recover, evacuate, and
recharge with specified
amount.
Suction (low)
pressure abnor-
mally low
Expansion valve is not frosted, and
low oressure line is not cold. Low
pressure gauge indicates vacuum.
. Frozen expansion valve. Faulty expansion valve
ReDlace the exoansion valve.
Discharge temperature is low. and
the air flow from vents is restricted.
Frozen evaporatorRun the fan with compressor
off. then check A,/C thermostat.
Exoansion valve is frosted.Clogged expansion valveClean or replace.
Receiver/dryer outlet is cool, and
inlet is warm (should be warm
during operation).
Clogged receiver/dryerReplace.
Suction pres-
sure abnormally
hig h
Low pressure hose and check
joint are cooler than the tempera-
ture around evaporator.
. Expansion valve open too
long. Loose expansion capillary
tube
Repair or replace.
Suction oressure is lowered when
condenser is cooled bv water.
Excessive refrigerant in sys-
tem
Recover. evacuate, and
recharge with specified amount.
High and low pressure are equal-
ized as soon as the compressor is
stopped, and both gauges fluctu-
ate while running.
Faulty gasket
Faulty high pressure valve
Foreign particle stuck in
high pressure valve
Replace the compressor.
Suction and dis-
charge pres-
sures abnormally
h igh
Reduced air flow through con-
denser.
. Clogged condenser fins. Condenser fan not work-
ing properly
Clean condenser.
Check voltage and fan rpm.
Check fan direction.
Suction and dis-
charge pressure
abnormally low
Low pressure hose and metal end
areas are cooler than evaporator.
Clogged or kinked low pres-
sure hose parts
Repair or replace.
Temperature around expansion
valve is too low compared with
that around receiver/dryer.
Clogged high pressure lineRepair or replace.
Refrigerant leaksCompressor clutch is diny,Compressor shaft seal leakingReplace the compressor.
Compressor bolt{s) are diny.Leaking around bolt(s)Tighten bolt(s) or replace com-
pressor.
Compressor gasket is wet with oil.Gasket leakingReplace the compressor.
22-26

Evaporator
1.
Replacement
4.
Move the temperature control to "HOl"
'96-98: Slide the temoerature control lever.'99-00: Turn the ignition switch ON (ll), then turn
the temperature contol knob. Turn the ignition
switch off.
Remove the battsry.
Rgcover the refrigerant with a rocovery/recycling/
charging station (see page 22-271.
Remove the bolts, then disconnect th6 suction 8nd
receiver lines from th6 evaoorator.
NOTE: Plug or cap the lines imm€diatoly after dis-
connecting them to avoid moisture and dust con-
tamination.
6xl.0mm9.8 n*ln ll.0 tg6m.7.2 lbt frl
RECEiVER UNE
Remove the glov6 box (see section 20).
Removo the self-tapping scr€w and the passeng€r's
dashboard lower cover. Removs the bolt. the nut
8nd the kn€e bolst6r, th6n r6mov6 th6 fiv6 bolts and
the glove box frame.
6.
srrcrrc u E
22-28
7. Disconnect the connector from th€ Ay'C thermostat,
and r€movs the wire harness from the ovaporator.
Remov6 tho four self-tapping screws, tho mounting
bolt and ths mounting nut. Disconnect th€ drain
hose, then remov€ th6 avagorator.
6 x l.0.nm9.8 l$m lt.o ldm, 7.2 bl.tt)
Install in the reverse order of removal. Make note of
th€ following items.
o lf you'r6 installing a new evaporator, add rofriger-
ANt OiI {SANDEN, SP-10 Or DENSO, ND-OIL 8)
lsas page 22-221.
. Replace the O-rings with now ones 8t 68ch titting,
and apply 8 thin coat of r€frlgersd oil before
installing them.
NOTE: Be sure to use the right O-rings for HFC-
134a (R-134a) to avoid loakago.
. Apply s€alant to tha grommets.
. Mske sure that ther€ is no air leakage.
. Chargs ths system {s€€ page 22-161, and tost its
performance (see pags 22-211.

Overhaul
1.
3.
Pull out the A,/C thermostat sensor from the evapo-
rator fins.
Remove the self-tapping screws and clamps from
the housings.
Carefully separate the housings, then remove the
evaporator.
lf necessary, remove the expansion valve.
NOTE: When loosening the expansion valve nuts, use
a second wrench to hold the expansion valve or the
evaporator pipe. Otherwise, they can be damaged
5. Assemble in the reverse order of disassembly Make
note of following items.
. Replace the O-rings with new ones at each fitting,
and apply a thin coat of refrigerant oil before
installing them.
NOTE: Be sure to use the right O-rings for HFC-
134a (R-134a) to avoid leakage.
. Install the expansion valve capillary tube so that
it is in direct contact with the suction line. Then
wrap wath taPe.
. Reinstall the Ay'C thermostat sensor to its original
location.
6th tin lrom inld side
Serpentine type:
Laminate typo:
TAPEReplace.lvake sure there is no foreign matter stuck between
60t5mml'2.1! O.2 inl
EVAPORATORblow din out of linswith compressed air,
HOUSING
8 N.m 10.8 kgt m,6 tbf.ftl
6th fin lrom outle't sideCAPILLARY TUAE
VALVEN
u'
ll
6\N.m (2.it kgt.m,17 tbtftl1l
A/C THERMOSTfesr page 22 21
%
EVAPORA
LOWER
22-29

Gonnector ldentification and Wire Harness Routing
Heater Sub-harness A: '96 - 98 models
Connector or
Terminal
Number ot
CavitiesLocationConneqts toNotes
c7 21
c722
c723
c724
c727
7
20
2
Under left side of dash
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Main wire harness (C440)
Mode control motor
Heater sub-harness B 1C741)Ay'C thermostat
Blower motor
Blower resister
Recirculation control motor
Heater Sub-harness B: '96 - 98 mod€ls
HEATER SUB.HARNESS A
Connoctor 01
Terminal
Number of
CavitiesLocationConngcts loNotes
c7 41
c142
c7 43
20
14
Behind glove box
Behind middle of dash
Behind middle of dash
Heater sub-harness A (C723)
Heater fan switch
Heater control panel
23-58
HEATER SUB-HARNESS B

'
Heater Sub-harness A: '99 - 00 models
Connector or
Terminal
Number of
CavitiesLocationConnects toNotes
c721
c722
c723
c724
c725
c726
c727
c728
c729
c730
7
24
3
2
4
1
5
4
Under left side of dash
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Behind glove box
Main wire harness (C440)
Mode control motor
Heater sub-harness B (C741)
lilc thermostat
Blower motor
Power transistor
Recircuiation control motor
Heater sub-harness B (C744)
Air mix control motor
Blower motor high relaY
Heater Sub-harness B: '99 - 00 models
HEATER SUB.HARNESS A
Connector or
Terminal
Number of
CavitiesLocationConnects toNotes
c7 41
c'742
c143
c744
20
8
20
1
Behind glove box
Behind middie of dash
Behind middle of dash
Behind glove box
Heater sub-harness A (C723)
Heater control Panel
Heater control Panel
Heater sub-harness A (C728)

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MOOECONTROLMOTORPage 61-1' o( 61-2
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BLOWERMOTORRELAYPage 60or 60-1PHO|O9 '.a-4.1
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CLUTCHNELAYPage 62
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HEATERCONTROLPANELPages 61,62-1, and63-1
H EATERCONTROLPANEL
60-1,61-2,62 2,63 2,and 64- 1
TION A/CTHERMOSTATPages 62-1,62-2,63-1,and 63 2PAO|O 82 f96- 98)
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CONDENSENFANRELAYPage 63
COMPRESSON FAN
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RECIRCULATI(CONTROLMOTORPage 61 or 61,2
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