1993 CHEVROLET DYNASTY Service Manual

change language coolant temperature deactivate airbag open gas tank gas type coolant level

Page 2305 of 2438

CHEVROLET DYNASTY 1993 Service Manual HEATING AND AIR CONDITIONING
CONTENTS
page page
AUTOMATIC TEMPERATURE CONTROL (ATC) .............................. 66
COMPONENT SERVICE PROCEDURES ...... 47
FIXED DISPLACEMENT COMPRESSORÐ MODEL 1

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

Page 2306 of 2438

CHEVROLET DYNASTY 1993 Service Manual 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
fl

Page 2307 of 2438

CHEVROLET DYNASTY 1993 Service Manual 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

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

Page 2308 of 2438

CHEVROLET DYNASTY 1993 Service Manual 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

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

Page 2309 of 2438

CHEVROLET DYNASTY 1993 Service Manual VACUUM CIRCUITSÐHEATER OR HEATER A/C CONTROL
Ä HEATING AND AIR CONDITIONING 24 - 5

Page 2310 of 2438

CHEVROLET DYNASTY 1993 Service Manual 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, d

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

Page 2311 of 2438

CHEVROLET DYNASTY 1993 Service Manual (5) Insert a thermometer in the left center A/C
outlet and operate the engine for five minutes. The
A/C clutch may cycle depending on ambient condi-
tions. (6) With the A/C clutch engaged, compare th

Page 2312 of 2438

CHEVROLET DYNASTY 1993 Service Manual REFRIGERANT SERVICE PROCEDURES INDEX
page page
Adding Partial Refrigerant Charge ............ 10
Charging Refrigerant SystemÐEmpty System . . . 11
Discharging Refrigerant System .............. 11

REFRIGERANT SERVICE PROCEDURES INDEX
page page
Adding Partial Refrigerant Charge ............ 10
Charging Refrigerant SystemÐEmpty System . . . 11
Discharging Refrigerant System .............. 11
Evacuating Refrigerant System .............. 11
Manifold Gauge Set Connections ............. 9 Oil Level
............................... 12
R-12 Refrigerant Equipment ................. 8
Refrigerant Recycling ...................... 9
Sight Glass Refrigerant Level Inspection ........ 8
Testing for Refrigerant Leaks ............... 10
SIGHT GLASS REFRIGERANT LEVEL INSPECTION
The filter-drier is equipped with a sight glass (Fig.
1) that is used as a refrigerant level indicator only.
This sight glass is not to be used for A/C perfor-
mance testing. To check the refrigerant level re-
move the vehicle jack. Then clean the sight glass,
start and warm up engine, and hold rpm slightly
above idle (1100 rpm). Place the air conditioning con-
trol on A/C, RECIRC and high blower. The work
area should be at least 21ÉC (70ÉF). If a Fixed Dis-
placement type compressor does not engage, the re-
frigerant level is probably too low for the Low
Pressure Cut-Off switch to detect. Or, with a Vari-
able Displacement compressor, for the Differential
Pressure Cut-off to detect. If compressor clutch does
not engage, test the refrigerant system for leaks. If
compressor clutch engages, allow approximately one
minute for refrigerant to stabilize. View refrigerant
through sight glass. The suction line should be cold
to the touch and the sight glass should be clear.
If foam or bubbles are visible in sight glass, the re- frigerant level is probably low. Occasional foam or
bubbles are normal when the work area temperature
is above 43ÉC (110ÉF) or below 21ÉC (70ÉF). If suction
line is cold and occasional bubbles are visible in the
sight glass, block the condenser air flow. This will in-
crease the compressor discharge pressure. Do not al-
low engine to over heat. Bubbles should dissipate.
If not, the refrigerant level is low.
CAUTION: Do not allow engine to over heat while
blocking the condenser air flow.
WARNING: R-12 REFRIGERANT IS DETRIMENTAL
TO THE ENVIRONMENT WHEN RELEASED TO THE
ATMOSPHERE. DO NOT ADD R-12 REFRIGERANT
TO A SYSTEM THAT HAS A KNOWN LEAK.
The refrigerant system will not be low on (R-12)
unless there is a leak. Find and repair the leak be-
fore charging.
R-12 REFRIGERANT EQUIPMENT
WARNING: EYE PROTECTION MUST BE USED
WHEN SERVICING AN AIR CONDITIONING REFRIG-
ERANT SYSTEM. TURN OFF (ROTATE CLOCKWISE)
ALL VALVES ON THE EQUIPMENT BEING USED
BEFORE PROCEEDING WITH THIS OPERATION.
PERSONNEL INJURY CAN RESULT.
When servicing an air conditioning system, an A/C
charging station is recommended (Fig. 2). An (R-12)
refrigerant recovery/recycling device (Fig. 3) should
also be used. This device should meet SAE standards.
Contact an automotive service equipment supplier
for refrigerant recycling/recovering equipment. Refer
to the operating instructions provided with the
equipment for proper operation. A manifold gauge set (Fig. 4) must also be used in
conjunction with the charging and/or recovery/recy-
cling device. The service hoses on the gauge set be-
ing used should have manual (turn wheel) or
automatic back flow valves at the service port con-
nector ends. This will prevent refrigerant from being
release into the atmosphere.
Fig. 1 Filter Drier and Sight Glass
24 - 8 HEATING AND AIR CONDITIONING Ä

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