heater CHEVROLET DYNASTY 1993 Workshop Manual

gage compartment. If light is visible through a nor-
mally sealed location, water could enter through the
opening.
PRESSURIZED LEAK TEST METHOD
When a water leak into the passenger compartment
can not be detected by water testing, pressurize the
passenger compartment and soap test exterior of the
vehicle. To pressurize the passenger compartment,
close all doors and windows, start engine, and set
heater control to high blower in HEAT position. If
engine can not be started, connect a charger to the
battery to assure adequate voltage to the blower. With
interior pressurized, apply dish detergent solution to
suspected leak area on the exterior of the vehicle.
Apply detergent solution with spray device or soft
bristle brush. If soap bubbles occur at a body seam,
joint, seal or gasket the leak entry point could be at
that location.
WIND NOISE
Wind noise is the result of most air leaks. Air leaks
can be caused by poor sealing, improper body compo-
nent alignment, body seam porosity, or missing plugs
in the engine compartment or door hinge pillar areas.
All body sealing points should be air tight in normal
driving conditions. Moving sealing surfaces will not
always seal air tight under all conditions. At times,
side glass, door, or convertible top seals will allow wind
noise to be noticed in the passenger compartment
during high cross-winds. Over compensating on door,
glass, or top adjustments to stop wind noise that occurs
under severe conditions, can cause premature seal
wear and excessive closing or latching effort. After a repair procedure has been performed, test vehicle to
verify leak has stopped before returning vehicle to use. Wind noise can also be caused by improperly fitted
exterior mouldings or body ornamentation. Loose
mouldings can flutter, creating a buzzing or chattering
noise. An open cavity or protruding edge can create
whistling or howling noise. Inspect the exterior of the
vehicle to verify that these conditions do not exist.
VISUAL INSPECTION BEFORE TESTS
Verify that floor and body plugs are in place, body
drains are clear and body components are aligned and
sealed. If component alignment or sealing is necessary,
refer to the appropriate section of this group for proper
procedures.
ROAD TESTING WIND NOISE
(1) Drive the vehicle to verify the general location of
the wind noise. (2) Apply 50 mm (2 in.) masking tape in 150 mm (6
in.) lengths along weatherstrips, weld seams or moul-
dings. After each length is applied drive vehicle. If
noise goes away after a piece of tape is applied, remove
tape, locate and repair defect.
POSSIBLE CAUSE OF WIND NOISE
² Mouldings standing away from body surface can
catch wind and whistle.
² Gaps in sealed areas behind overhanging body
flanges can cause wind rushing sounds.
² Misaligned movable components.
² Missing or improperly installed plugs in pillars.
² Weld burn through holes.
Ä BODY 23 - 3

HEATING AND AIR CONDITIONING
CONTENTS
page page
AUTOMATIC TEMPERATURE CONTROL (ATC) .............................. 66
COMPONENT SERVICE PROCEDURES ...... 47
FIXED DISPLACEMENT COMPRESSORÐ MODEL 10PA17 ...................... 24
FIXED DISPLACEMENT COMPRESSORÐ MODEL SD709P ...................... 38 FIXED DISPLACEMENT COMPRESSORÐ
MODEL TR105 ....................... 32
GENERAL INFORMATION .................. 1
HEATER AND A/C PERFORMANCE TESTS .... 6
REFRIGERANT SERVICE PROCEDURES ...... 8
VACUUM CONTROL SYSTEM DIAGNOSIS .... 4
VARIABLE DISPLACEMENT COMPRESSORÐ MODEL 6C17 ......................... 13
GENERAL INFORMATION INDEX
page page
A/C System Identification ................... 1
Cooling System Precautions ................. 3
Description and Operation ................... 1
Engine Cooling System Requirements .......... 2 Handling Tubing and Fittings
................. 3
Safety Precautions and Warnings ............. 3
Side Window Demisters .................... 2
System Airflow ........................... 1
A/C SYSTEM IDENTIFICATION
The terms Fixed Displacement Compressor and
Variable Displacement Compressor will be used to
describe the two types of A/C systems used through-
out this Group. Refer to (Figs. 1, 2, 3 and 4). The Variable Displacement Compressor can be
identified by the location of the high pressure line. It
is mounted to the end of the compressor case (Fig. 4).
DESCRIPTION AND OPERATION
Both the heater and the heater/air conditioning
systems share many of the same functioning compo-
nents. This Group will deal with both systems to-
gether when component function is common, and
separately when they are not. For proper operation of the instrument panel con-
trols, refer to the Owner's Manual provided with the
vehicle. All vehicles are equipped with a common A/C-heat-
er unit housing assembly. On heater only systems,
the evaporator and recirculating air door are omitted
(Fig. 5).
SYSTEM AIRFLOW
The system pulls outside (ambient) air through the
cowl opening at the base of the windshield. Then it
goes into the plenum chamber above the A/C-heater unit housing. On air conditioned vehicles, the air
passes through the evaporator. Air flow can be di-
rected either through or around the heater core. This
Fig. 1 Fixed Displacement CompressorÐModel 10PA17
Ä HEATING AND AIR CONDITIONING 24 - 1

is done by adjusting the blend-air door with the
TEMP control on the instrument panel. The air flow
can then be directed from the PANEL, BI-LEVEL
(panel and floor), and FLOOR-DEFROST outlets. Air
flow velocity can be adjusted with the blower speed
selector switch on the instrument panel (Fig. 6). On air conditioned vehicles, ambient air intake can
be shut off by closing the recirculating air door. This
will recirculate the air that is already inside the ve-
hicle. This is done by moving the TEMP control into
the RECIRC position. Depressing the DEFROST or
A/C button will engage the compressor. This will send refrigerant through the evaporator, and will re-
move heat and humidity from the air before it is di-
rected through or around the heater core.
SIDE WINDOW DEMISTERS
The side window demisters direct air from the
heater assembly. The outlets are located on the top
outboard corners of the instrument panel. The De-
misters operate when the A/C control mode selector
is on FLOOR or DEFROST setting.
ENGINE COOLING SYSTEM REQUIREMENTS
To maintain the performance level of the heating/
air conditioning system, the engine cooling system
must be prepared as shown in this manual. The use of a bug screen is not recommended. Any
obstructions in front of the radiator or condenser can
reduce the performance of the A/C or engine cooling
system.
Fig. 2 Fixed Displacement CompressorÐModel TR105
Fig. 3 Fixed Displacement CompressorÐModelSD709P
Fig. 4 Variable Displacement CompressorÐModel 6C17
Fig. 5 Common Blend-Air Heater A/C System
24 - 2 HEATING AND AIR CONDITIONING Ä

SAFETY PRECAUTIONS AND WARNINGS
WARNING: WEAR EYE PROTECTION WHEN SER-
VICING THE AIR CONDITIONING REFRIGERANT
SYSTEM. SERIOUS EYE INJURY CAN RESULT
FROM EYE CONTACT WITH REFRIGERANT. IF EYE
CONTACT IS MADE, SEEK MEDICAL ATTENTION
IMMEDIATELY. DO NOT EXPOSE REFRIGERANT TO OPEN
FLAME. POISONOUS GAS IS CREATED WHEN RE-
FRIGERANT IS BURNED. AN ELECTRONIC TYPE
LEAK DETECTOR IS RECOMMENDED. LARGE AMOUNTS OF REFRIGERANT RELEASED
IN A CLOSED WORK AREA WILL DISPLACE THE
OXYGEN AND CAUSE SUFFOCATION. THE EVAPORATION RATE OF (R-12) REFRIGER-
ANT AT AVERAGE TEMPERATURE AND ALTITUDE
IS EXTREMELY HIGH. AS A RESULT, ANYTHING
THAT COMES IN CONTACT WITH THE REFRIGER-
ANT WILL FREEZE. ALWAYS PROTECT SKIN OR
DELICATE OBJECTS FROM DIRECT CONTACT
WITH REFRIGERANT.
CAUTION: Liquid refrigerant is corrosive to metal
surfaces. Follow the operating instructions supplied
with equipment being used.
COOLING SYSTEM PRECAUTIONS
WARNING: ANTIFREEZE IS AN ETHYLENE GLYCOL
BASE COOLANT AND IS HARMFUL IF SWAL-
LOWED OR INHALED. IF SWALLOWED, DRINK
TWO GLASSES OF WATER AND INDUCE VOMIT-
ING. IF INHALED, MOVE TO FRESH AIR AREA.
SEEK MEDICAL ATTENTION IMMEDIATELY. DO NOT STORE IN OPEN OR UNMARKED CON-
TAINERS. WASH SKIN AND CLOTHING THOROUGHLY AF-
TER COMING IN CONTACT WITH ETHYLENE GLY-
COL. KEEP OUT OF REACH OF CHILDREN AND PETS.
DO NOT OPEN A COOLING SYSTEM WHEN THE
ENGINE IS AT RUNNING TEMPERATURE. PER-
SONAL INJURY CAN RESULT.
The engine cooling system is designed to develop
internal pressure of 97 to 123 kPa (14 to 18 psi). Al-
low the vehicle 15 minutes (or until a safe tempera-
ture and pressure are attained) before opening the
cooling system. Refer to Group 7, Cooling System.
HANDLING TUBING AND FITTINGS
Kinks in the refrigerant tubing or sharp bends in
the refrigerant hose lines will greatly reduce the ca-
pacity of the entire system. High pressures are pro-
duced in the system when it is operating. Extreme
care must be exercised to make sure that all connec-
tions are pressure tight. Dirt and moisture can enter
the system when it is opened for repair or replace-
ment of lines or components. The refrigerant oil will
absorb moisture readily out of the air. This moisture
will convert into acids within a closed system. The following precautions must be observed:
The system must be completely empty before open-
ing any fitting or connection in the refrigeration sys-
tem. Open fittings with caution even after the
system has been emptied. If any pressure is noticed
as a fitting is loosened, allow trapped pressure to
bleed off very slowly. A good rule for the flexible hose lines is to keep the
radius of all bends at least 10 times the diameter of
the hose. Sharper bends will reduce the flow of re-
frigerant. The flexible hose lines should be routed so
they are at least 3 inches (80 mm) from the exhaust
manifold. Inspect all flexible hose lines to make sure
they are in good condition and properly routed. Unified plumbing connections with aluminum gas-
kets cannot be serviced with O-rings. These gaskets
are not reusable and do not require lubrication be-
fore installing. The use of correct wrenches when making connec-
tions is very important. Improper wrenches or im-
proper use of wrenches can damage the fittings. The A/C system will remain chemical stabile as
long as pure-moisture-free R-12 and refrigerant oil is
used. Abnormal amounts of dirt, moisture or air can
upset the chemical stability. This condition could
cause operational troubles or even serious damage if
present in more than very small quantities. When it is necessary to open the refrigeration sys-
tem, have everything needed to service the system
ready. The system should not be left open any longer
than necessary. Cap or plug all lines and fittings as
soon as they are opened to prevent the entrance or
dirt and moisture. All lines and components in parts
stock should be capped or sealed until they are ready
to be used. All tools, including the refrigerant dispensing man-
ifold, the manifold gauge set, and test hoses should
be kept clean and dry.
Fig. 6 Heater only or HeaterÐA/C Controls
Ä HEATING AND AIR CONDITIONING 24 - 3

VACUUM CONTROL SYSTEM DIAGNOSIS
GENERAL INFORMATION
Use an adjustable Vacuum Test Gauge (C-3707)
and a suitable vacuum pump to test heater A/C con-
trol vacuum. With a finger placed over the end of
test hose (Fig. 1), calibrate vacuum control valve on
the test gauge to obtain -27 kPa (8 in. Hg.). Release
and block the end of the test hose several times to
verify vacuum setting.
VACUUM TESTING THE ONE-WAY CHECK VALVE
(1) In the engine compartment, disconnect the
Heater-A/C vacuum supply (black) hose. This hose
passes through an opening in the dash panel used for
the air conditioning expansion valve. (2) Remove the vacuum check valve. This valve is
located on the (black) vacuum supply hose at the
brake power booster. (3) Connect test vacuum supply hose to the heater
side of the valve. In this direction the gauge should
return to calibrated setting. If valve leaks vacuum in
this direction, valve replacement is necessary. (4) Connect test vacuum supply hose to the engine
vacuum side of the valve. Vacuum should flow
through valve.
VACUUM TESTING THE HEATER-A/C CONTROLS
(1) Connect the test vacuum prod to the vehicles
(black) vacuum supply hose. Position vacuum test
gauge so it can be viewed from the passenger com-
partment. (2) Position the heater A/C control mode selector to
DEFROST, FLOOR, BI-LEVEL, PANEL, and RE-
CIRC (with A/C). Pause after each selection. The test
gauge should return to the calibrated setting of -27
kPa (8 in. Hg.) after each selection is made. If the
gauge cannot achieve the calibrated setting, a vac-
uum circuit or component has a leak.
LOCATING VACUUM LEAKS
To locate a vacuum leak, disconnect 7-way vacuum
connector behind the instrument panel at the heater
A/C control. For removal and installation of heater
A/C control panel, refer to the Switch and Panel
Component Service section of Group 8E, Instrument
Panel. Connect the calibrated vacuum hose prod (Fig.
4) to each port in the vacuum harness connector (Fig.
2). The brown, bi-level, vacuum circuit has a metal
fiber restrictive device located in the line. More reac-
tion time is required for the test gauge to return to
calibrated setting. After each connection is made, the
test gauge should return to calibrated setting. If all
circuits function properly, replace control mode vac-
uum switch. If not, determine the color of the vac-
uum circuit that is leaking. To determine vacuum
line colors, refer to the Vacuum Circuits-Heater or
Heater A/C Control chart in this section. Disconnect
the vacuum actuator at the other end of the circuit.
(Instrument panel removal may be necessary to gain
access to some components). Block the end of the dis-
connected vacuum line. The test gauge should return
to calibrated setting. If not, that circuit has a leak
and must be repaired or replaced. If test gauge re-
turns to calibrated setting, the vacuum actuator
must be replaced.
Fig. 1 Adjust Vacuum Test Bleed Valve
Fig. 2 Vacuum Circuit Test
24 - 4 HEATING AND AIR CONDITIONING Ä

VACUUM CIRCUITSÐHEATER OR HEATER A/C CONTROL
Ä HEATING AND AIR CONDITIONING 24 - 5

HEATER AND A/C PERFORMANCE TESTS
HEATER OUTPUT TEST
PRE-DIAGNOSTIC PREPARATIONS
Review Safety Precautions and Warnings before
performing the following procedures. Check the radiator coolant level, drive belt tension,
and engine vacuum line connections. Also check ra-
diator air flow and radiator fan operation. Start en-
gine and allow to warm up to normal operating
temperature.
WARNING: DO NOT REMOVE RADIATOR CAP
WHEN ENGINE IS HOT, PERSONAL INJURY CAN
RESULT.
If vehicle has been run recently, wait 15 minutes
before removing cap. Place a rag over the cap and
turn it to the first safety stop. Allow pressure to es-
cape through the overflow tube. When the system
stabilizes, remove the cap completely.
MAXIMUM HEATER OUTPUT: TEST AND ACTION
Engine coolant is provided to the heater system by
two 16 mm (5/8 inch inside diameter) heater hoses.
With engine idling at normal running temperature,
set the control to maximum heat, floor, and high
blower setting. Using a test thermometer, check the
air temperature coming from the floor outlets, refer
to Temperature Reference chart.
If the floor outlet air temperature is low, refer to
Group 7, Cooling System for coolant temperature
specifications. Both heater hoses should be HOT to
the touch. The coolant return hose should be slightly
cooler than the supply hose. If coolant return hose is
much cooler than the supply hose, locate and repair
engine coolant flow obstruction in heater system.
POSSIBLE LOCATIONS OR CAUSE OF OBSTRUCTED
COOLANT FLOW
(a) Pinched or kinked heater hoses.
(b) Improper heater hose routing. (c) Plugged heater hoses or supply and return
ports at cooling system connections, refer to Group
7, Cooling System. (d) Plugged heater core.
If proper coolant flow through heater system is ver-
ified and outlet air temperature is still low, a me-
chanical problem may exist.
POSSIBLE LOCATION OR CAUSE OF INSUFFICIENT HEAT
(a) Obstructed cowl air intake.
(b) Obstructed heater system outlets.
(c) Blend-air door not functioning properly.
TEMPERATURE CONTROL If temperature cannot be adjusted with the TEMP
lever on the control panel, or TEMP lever is difficult
to move, the following could require service: (a) Blend-air door binding.
(b) Control cables miss-routed, pinched, kinked,
or disconnected. (c) Improper engine coolant temperature.A/C PERFORMANCE TEST
The air conditioning system is designed to remove
heat and humidity from the air entering the passen-
ger compartment. The evaporator, located in the
heater A/C unit behind the instrument panel, is
cooled to temperatures near the freezing point. As
warm damp air passes over the fins in the evapora-
tor, moisture in the air condenses to water, dehumid-
ifying the air. Condensation on the evaporator fins
reduces the evaporators ability to absorb heat. Dur-
ing periods of high heat and humidity an A/C system
will be less effective than during periods of high heat
and low humidity. With the instrument control set to
RECIRC, only air from the passenger compartment
passes through the evaporator. As the passenger
compartment air dehumidifies, A/C performance lev-
els rise.
PERFORMANCE TEST PROCEDURE
Review Safety Precautions and Warnings before
proceeding with this procedure. Air temperature in
test room and on vehicle must be 70ÉF (21ÉC) mini-
mum for this test. (1) Connect a tachometer and manifold gauge set.
(2) Set control to A/C, RECIRC, PANEL, or MAX
A/C, temperature lever on full cool and blower on
high. (3) Start engine and hold at 1000 rpm with A/C
clutch engaged. (4) Engine should be warmed up with doors and
windows closed.
TEMPERATURE REFERENCE CHART
24 - 6 HEATING AND AIR CONDITIONING Ä

WARNING: REVIEW SAFETY PRECAUTIONS AND
WARNINGS BEFORE CHARGING THE REFRIGER-
ANT SYSTEM.
After the system has been tested for leaks and
evacuated, a refrigerant charge can be injected into
the system. (1) Connect manifold gauge set.
(2) Measure refrigerant (refer to capacities) and
heat to 52ÉC (125ÉF) with the charging station. Refer
to the instructions provided with the equipment be-
ing used.
REFRIGERANT CAPACITIES:
² Without Rear A/C = 907 g (32 oz.)
² With Rear A/C = 1219 g (43 oz.)
(3) Open the suction and discharge valves. Open
the charge valve to allow the heated refrigerant to
flow into the system. When the transfer of refriger-
ant has stopped, close the suction and discharge
valve. (4) If all of the refrigerant charge did not transfer
from the dispensing device, start engine and hold at
idle (1400 rpm). Set the A/C control to A/C, low
blower speed, and open windows. If the A/C compres-
sor does not engage, test the compressor clutch con-
trol circuit and correct any failure. Refer to Group
8W, Wiring Diagrams. (5) Open the suction valve to allow the remaining
refrigerant to transfer to the system.
WARNING: TAKE CARE NOT TO OPEN THE DIS-
CHARGE (HIGH-PRESSURE) VALVE AT THIS TIME.
(6) Close all valves and test the A/C system perfor-
mance. Refer to Heater and A/C Performance Tests
in this Group. (7) Disconnect the charging station or manifold
gauge set. Install the service port caps.
OIL LEVEL
It is important to have the correct amount of oil in
the A/C system to ensure proper lubrication of the
compressor. Too little oil will result in damage to the
compressor. Too much oil will reduce the cooling ca-
pacity of the system. The oil used in the compressor is a 500 SUS viscos-
ity, wax-free refrigerant oil. Only refrigerant oil of
the same type should be used to service the system.
Do not use any other oil. The oil container should be
kept tightly capped until it is ready for use, and then
tightly capped after use to prevent contamination
from dirt and moisture. Refrigerant oil will quickly
absorb any moisture it comes in contact with. It will not be necessary to check oil level in the
compressor or to add oil unless there has been an oil
loss. This may be due to a ruptured line, shaft seal leakage, leakage from the evaporator, condenser
leak, filter drier or loss of refrigerant due to a colli-
sion. Oil loss at a the leak point will be evident by
the presence of a wet, shiny surface around the leak.
REFRIGERANT OIL LEVEL CHECK
When an A/C system is assembled at the factory,
all components (except the compressor) are refriger-
ant oil free. After the system has been charged with
R-12 and operated, the oil in the compressor is dis-
persed through the lines and components. The evap-
orator, condenser, and filter-drier will retain a
significant amount of oil. (Refer to the Refrigerant
Oil Capacities chart). When a component is replaced,
the specified amount of refrigerant oil must be
added. When the compressor is replaced, the amount
of oil that is retained in the rest of the system must
be drained from the replacement compressor. When a
refrigerant line or component has ruptured and it
has released an unknown amount of oil. The A/C
compressor should be removed and drained through
the suction port. The filter-drier must be replaced
along with the ruptured part. Then the oil capacity
of the system (minus the amount of oil still in the re-
maining components) can be poured into the suction
port of the compressor. Example: The evaporator retains 60 ml (2 oz). The
condenser retains 30 ml (1 oz) of oil, and system ca-
pacity may be 214 ml (7.25 oz) of oil. 214 ml minus 90 ml = 124 ml (4.25 oz).
VERIFY REFRIGERANT OIL LEVEL
(1) Using a refrigerant recovery machine, remove
refrigerant from the A/C system. (2) Remove refrigerant lines from A/C compressor.
(3) Remove compressor from vehicle.
(4) From suction port on top of compressor, drain
refrigerant oil from compressor. (5) Add system oil capacity minus the capacity of
components that have not been replaced. Refer to the
Refrigerant Oil Capacity chart. Add oil through suc-
tion port on compressor. (6) Install compressor, connect refrigerant lines,
evacuate, and charge refrigerant system.
REFRIGERANT OIL CAPACITIES
24 - 12 HEATING AND AIR CONDITIONING Ä

VARIABLE DISPLACEMENT COMPRESSORÐMODEL 6C17 INDEX
page page
Clutch Coil Tests ......................... 17
Compressor ............................. 17
Compressor Clutch Inoperative .............. 13
Compressor Clutch/Coil Assembly ............ 19
Compressor Diagnosis ..................... 13
Compressor Front Shaft Seal ............... 20 Compressor High Pressure Cut-Out Switch
..... 21
Compressor High Pressure Relief Valve (HPR) . . 22
Compressor Identification ................... 13
Compressor Main or Sub Control Valves ....... 22
Compressor Noise ........................ 13
General Information ....................... 13
GENERAL INFORMATION
The Variable Displacement Compressor (VDC) pro-
vides maximum A/C performance under most condi-
tions. It is designed to operate continuously without
any cycling of the compressor clutch. The compressor
has a variable angle wobble plate with six axially
oriented cylinders. During vehicle A/C system operation, the compres-
sor will change its displacement to match the vehi-
cles A/C cooling demands. When the A/C system
needs more cooling capacity, the compressor will in-
crease its pumping capacity. This is done by increas-
ing the wobble plate angle to increase the piston
stroke. When the A/C system cooling demand is low,
the compressor will decrease its pumping capacity by
reducing the piston pumping stroke. The low cooling
capacity will prevent evaporator from freezing.
COMPRESSOR IDENTIFICATION
The Variable Displacement Compressor can be
identified by the location of the high pressure line. It
is mounted to the end of the compressor case (Fig. 1).
COMPRESSOR DIAGNOSIS
(1) Verify that refrigerant system is at full charge.
Refer to the Refrigerant Service Procedures section
in this Group. (2) Perform A/C Performance Test. Refer to Heater
and A/C Performance Test section in this Group. (3) If performance is not acceptable, perform ex-
pansion valve tests. Refer to Expansion Valve Tests
in this section. (4) If expansion valve test is correct, refer to the
Variable Displacement Compressor Diagnosis charts.
COMPRESSOR NOISE
Excessive noise that occurs when the air condition-
ing is being used, can be caused by:
² Loose bolts
² Mounting brackets
² Loose clutch
² Excessive high refrigerant system operating pres-
sure Verify compressor drive belt condition, proper re-
frigerant charge and head pressure before compressor
repair is performed. For noise diagnostic procedures, refer to the Com-
pressor Noise and Compressor Clutch Diagnosis
chart in this section.
COMPRESSOR CLUTCH INOPERATIVE
The air conditioning compressor clutch electrical
circuit is controlled by the engine controller. The
controller is located in the engine compartment out-
board of the battery. If the compressor clutch does not engage:
Verify refrigerant charge. Refer to Refrigerant Ser-
vice Procedures in this section. If the compressor clutch still does not engage:
Check for battery voltage at the differential pres-
sure cut-off switch located on the expansion valve. If
voltage is not detected, refer to: (1) Group 8W, Wiring Diagrams.
Fig. 1 Variable Displacement CompressorÐModel 6C17
Ä HEATING AND AIR CONDITIONING 24 - 13

COMPONENT SERVICE PROCEDURES INDEX
page page
Air Distribution Duct ...................... 50
Air Distribution Duct ...................... 52
Ambient Switch .......................... 47
Blend-Air Door .......................... 64
Blower Motor ............................ 58
Blower Motor Wheel Assembly .............. 58
Blower Resistor Block ..................... 49
Condensate Drain Tube ................... 64
Condenser Assembly ...................... 57
Condenser Fan Control Switch .............. 47
Defroster Duct ........................... 51
Defroster Duct Adapter .................... 51
Defroster Ducts/Demister Ducts and Hoses ..... 52
Differential Pressure Cut-Out Switch Diagnosis . . 48
Evaporator Coil .......................... 64 Expansion Valve
......................... 55
Filter-Drier Assembly ...................... 57
Fin-Sensing Cycling Clutch Switch ............ 53
Heater Core ............................ 64
Heater Hoses ........................... 51
Heater-A/C Unit AssemblyÐRemoval and Installation ............................ 61
Heater-A/C Unit Recondition ................ 63
Low or Differential Pressure Cut-Off Switch ..... 54
Temperature Control CableÐAA,AP,AG and AJ Models ............................ 49
Temperature Control CableÐAC/AY Models .... 48
Vacuum ActuatorÐFresh/Recirc Door ......... 50
Vacuum ActuatorsÐMode Doors ............. 52
AMBIENT SWITCH
The ambient switch is a temperature sensor located
in front of the condenser behind the grille (Fig. 1).
The ambient switch prevents the compressor from
engaging in cold temperatures. The ambient switch
is a sealed factory calibrated unit. It must be re-
placed if defective.
AMBIENT SWITCH TEST
(1) Disconnect ambient switch wire connector.
(2) Using a suitable ohm meter or continuity
tester, test for continuity across the ambient switch
terminals. (a) At temperature above 10ÉC (50ÉF), the switch
circuit should be complete. (b) Chill the switch with ice to below 10ÉC (50ÉF)
and test for continuity. The switch circuit should
be open, with continuity not detected.
Replace ambient switch if defective.
REMOVAL AND INSTALLATION
(1) Remove the one attaching screw.
(2) Remove the sensor/bracket assembly from the
vehicle. To install, reverse the preceding operation.
CONDENSER FAN CONTROL SWITCH
The Fan Control Switch is located on the plumbing
discharge line at the A/C compressor (Fig. 2). The fan
control switch cycles the radiator/condenser fan on and
off by monitoring the compressor discharge pressure.
The radiator top tank temperature sensor can over ride
the function of the fan control switch. It can cycle the
radiator/condenser fan on and off depending on the
engine temperature.
FAN CONTROL SWITCH DIAGNOSIS
Review Safety Precautions and Warnings before pro-
ceeding. Connect a manifold gauge set to the refriger-
ant system service ports. Work area temperature can
not be below 21ÉC (70ÉF).
Fig. 1 Ambient Temperature Sensor SwitchÐTypical Mounting
Fig. 2 Condenser Fan Control Switch
Ä HEATING AND AIR CONDITIONING 24 - 47