Thermostat test HONDA CIVIC 1996 6.G Workshop Manual

Cooling
fllustrated Index ."..."... ""' 10-2
Radiator
Replacement .'....'...."..."
Engine Coolant Refilling and
Bleeding
Cap Testing
Testing
Thermostat
Replacement .............'....
Testing
10-6
10-7
10-9
10-9
10-10
10-10
Engine Goolant TemPerature
(ECT) Switch
Testing """ 10-11
Water PumP
fffustrated Index ......'... " 10-12
Inspection ' 10'14
Replacement ..'..'...."...'.'....'..'.....'.""" 10-14
!

EGT Switch
-f
Testing
Replace the thermostat if it is open at room temperature'
To test a closed thermostat:
1, Suspend the thermostat in a container of water as
shown.
THEBMOMETER
THERMOSTAT
Heat the water, and check the temperature with a
thermometer. Check the temperature at which the
thermostat first opens, and at which it is fully open
CAUTION: Do not let the thermometer touch the
bottom of the hot Gonlainel.
Measure lift height of the thermostat when fully
open.
STANDARD THERMOSTAT
Lift height above 8.0 mm (0.31 inl
Starts opsning: 169' - 176'F (76' - 80'Cl
Fully open: 194'F {90"C1
!'o
10-1 1
Testing
!!@ Romoving the EcT swhch while lhs engine
i!-ot can cause the coolant to sPray out, seriously scald-
ing you. Always lst th€ ongine and rediator cool down
before removing ihe ECT switch.
NOTE: Bleed air from the cooling system after installing
the ECT switch (see Page 10-7)
1. Remove the ECT switch from the thermostat hous-
ing (see Page'10-10).
2. Suspend the ECT switch in a container of water as
shown.
Heat the water, and check the temperature with a
thermometer.
CAUTION: Do not let the thermomoter touch tho
bottom of the hot container'
Measure the resistance between the A and B termi-
nals according to the table.4.
Terminal
Oo"rffi
swlTcH
ON196' - 203"F
(91" - 95'C)o--o
OFF
5" - 15'F {3" - 8'C)
lower than the temPera-
ture when t goes on

Troubleshooting -'96 - 98 Models
Symptom Chart
NOTE;
. Check the engine coolant level. and allow the engine to warm up before troubleshooting.
. Any abnormality must be corrected before continuing the test.
. Because of the precise measurements needed. use a multimeter when testing.
o Before performing any troubleshooting procedures check:- Fuses No. 41 11.5 Al, No. 55 (40 A) in the under-hood fuse/relay box. and No. 17 (7.5 A) in the under-dash fuse/relay
box- Grounds No. G401, G402- Cleanliness and tightness of all connectors
SymptomRomedy
Hot air flow is low.Blower motor runs. but one or more
speeds are inoperative.
Perform the procedures in the flowchart (see page 21-8).
Blower runs properly.Check for the following:. Clogged heater duct. Clogged heater outlet. Incorrect door position
No hot air flow.Blower motor does not run at all,Perform the procedures in the flowchart (see page 21-10).
Blower motor runs.Check for the following:. Clogged heater duct. Clogged blower outlet. Clogged heater valve. Faultv air mix door. Heater valve cable adjustment (see page 21-44). Air mix control cable adiustment (see page 2'l-441. Faulty cooling system thermostat (see section 10). Clogged evaporator (with air conditioning). Frozen evaporator {with air conditioning)
Mode control motor does not run, or one or more modes
are inooerative.
Perform the procedures in the flowchart (see page 21-13).
Recirculation control door does not chanqe between
FRESH and RECIRCULATE.
Perform the procedu.es in the flowchan (see page 21-16).
Both heater and A,/C do not work.Perform the procedures in the flowchart (see page 21-18),
21-6

Air Conditioning
Speciaf Tools ......'.....' 22-2
f f f ustrated f ndex ......................... ".......' 22-3
Wiring/Connector Locations'.........'.... 22'4
Description
Outfine ............ .......22-s
Circuit Diagram
'96 - 98 Models ......"..........".......'.... 22-6
'99 Modef """""""' 22-7
Troubleshooting
Symptom Chart ".'......""................. 22-8
Flowcharts
Condenser Fan .........".................,..'. 22-9
Compressor .....""" 22-12
A/C System .........'.22'17
A/C Thermostat
Test ........'.......' """'22'21
Relays
Test ....."'......... ..""'22-21
A/C Service Tips and Precautions ......22-22
A/C System Torque Specifications '...22-23
A/C System Service
Performance Test ... '."......... ".... ....'..22-24
Pressure Test Chart .................. .... "' 22-26
Recovery ...".........," 22-27
Evaporator
Replacement .....",' 22'24
Overhauf .....-.....""' 22'29
Compressor {SANDEN}
Repf acement ......'.' 22-30
fffustrated fndex ......"..................'.... 22'32
Cf utch Inspection ......... "............ ...... 22-33
Clutch Overhau I ........................ ....... 22-34
Thermal Protector Replacement .... 22-36
Relief Valve Replacement ......'..."". 22-36
Compressor (DENSO)
Repfacement ..""',' 22-37
lf lustrated Index ............................... 22-39
Clutch lnspection ............."'...... "'.... 22-40
Cf utch Overhaul .....................'......... 22-41
Ref ief Valve Replacement'..'......"'.. 22-42
A/C Compressor Belt
Adiustment ............22'43
Condenser
Repfacement .......,,22'44
A/C System Service
Evacuation ...,,,.......22-45
Charging '..........--'..22'46
Leak rest """""""'22-46

lllustrated Index
A/C PRESSURE SWITCHWhen the refrigerant pressure is below 200 kPa {2 0 kg7cm',
28 psi) due to ;frigerant leakage or above 3200 kPa (32 kgf/cm''
455 psi) due to refrigerant blockage, the lVC pressure swrtch
SERVICE VALVE
{LOW.PRESSURE SIDE)
EVAPORATORReplacement, page 22-28
Overhaul, page 22 29
Beplacement, Page 22'44
opens lhe circuit to ihe AVC switch and stops the air condilioning
to protect the comPressor'
RECEIVER/DRYER
COMPRESSORSANDENIReplacement, Page 22 30
CIutch Inspection, Page 22 33
Thermal Protector Inspection, page 22 33
Clutch Overhaul, Page 22'34
Thermal Protector Replacement, page 22 36
Refief Vafve Replacemenl, page 22'36
DENSO:Replacement, Page 22-37
Clutch Inspection, Page 22-40
Clutch Overhaul, Page 22_41
Relief Valve Replacement, page 22-42
A/C THERMOSTATTest, page 22 21
22-3

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
t\----,'
t:n
,,l[4..-.
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

- How the Circuit Works
Battery voltage is supplied through tuse 56 to the
A,/C compressor clutch r€lay contacts at all times.
With the ignition switch in ON (ll), vollage is applied
to the coil of the A,/C compressor clutch relay
through fuse 17. When you push the A,/C switch
ON, and the heater fan switch is in position | , 2, 3,
or 4, a "ground" input is provided to the engine
control module (ECM) or powertrain control module
(PCM) through the l'lC thermostat and the l'lC
pressure switch.
The A,/C compressor clutch relay is grounded by the
engine control module (ECM) or powertrain control
module (PCM). When energized, the A'lC
compressor clutch relay allows battery voltage to
turn on the A,/C comDressor clutch.
The A,/C ON indicator light comes on when the A,/C
system is requested.
A,/C Thermostat
The A'lC thermostat is located on the evaoorator
housing. The A,/C thermostat turns off the A,/C
compressor clutch if the temperature at the
evaporator goes below 3'C (37'F). This prevents
condensation from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. The blower motor will keep running
when the sensor turns off the comDressor.
A,/C Pressure Switch
The fuC oressure switch is located in the condenser
outlet line where refrigerant is in a high
temperature/high pressure liquid state. The switch
will sense abnormally high or low pressure, and
open the circuit. This removes ground, and the
compressor will stop running.
Thermal Protectot
The thermal protector, located on the A,/C
compressor, opens and turns the compressor off if it
senses high temperature. Once the compressor
cools, the switch will close and the compressor will
begin running again.
Refer to the Service Manual (Section 22,
Air Conditioning) for specific tests or
troubleshooting procedures.
62-3

- How the Circuit Works
Radiator Fan
Voltage is provided at all times to the radiator fan
relay (contacts) through fuse 57. With the ignition
swilch in ON (ll), voltage is provided to the coil of
the relay through luse 17.
The radiator tan relay can be grounded through
either the engine coolant temperature switch or the
engine control module (ECM) or powertrain control
module (PCM).
The engine coolant temperature switch grounds
the radiator fan relay (coil) when the engine
coolant temperature exceeds 199'F (83'C). The
switch opens when coolanl temperature
decreases 3'- 8'C.
Condenser Fan
Voltage is provided at all times to the condenser fan
relay (contacts) through fuse 56. With the ignition
switch in ON (ll), voltage is provided to the coil of
the relay through fuse 17. When you push the A'lC
switch and put the heater fan switch in 1, 2,3, o( 4
position, the ly'C thermostat comes on, the
condenser fan relay energizes, and the condenser
fan motor runs.
A,/C Thermostat
The A,/C thermostat is located on the evaporator
housing. The A,/C thermostat tums off the A/C
compressor clutch if the temperature at the
evaporator goes below 3'C (37'F). This prevents
condensation from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. lf the temperature goes below 3'C
(37"F) tuming off the Ay'C thermostat, ground will be
removed from the condenser fan relay. This will
deenergize the relay and remove voltage from the
condenser fan motor causing the fan to stop running.
Reter to the Service Manual (Section 23, Eleckical)
for specific tests or troubleshooting procedures.
63-3