heating CHEVROLET DYNASTY 1993 Owners Manual

(1) Disconnect the boot like wire connector at the
cut-off switch. (2) Using a sender unit type socket, remove the
switch from the expansion valve (Fig. 22 or 23).
To install, assure an adequate seal by using a small
amount of thread sealing tape on the replacement
switch and reverse the preceding steps. Evacuate and charge the system.
EXPANSION VALVE
DIAGNOSIS
BLACK EXPANSION VALVE TEST
Liquid CO
2is required to test the expansion
valve. It is available from most welding supply
facilities. CO
2is also available from companies
which service and sell fire extinguishers. Review Safety Precautions and Warnings before pro-
ceeding with this operation. The work area must be 21ÉC to 27ÉC (70ÉF to 85ÉF) when testing expansion
valve. To test the expansion valve: (1) Connect a charging station or manifold gauge set
to the refrigerant system service ports. (2) Verify the refrigerant charge level using the sight
glass method. (3) Disconnect the wire connector at the differential
pressure cut-off switch. Using a jumper wire, jump
across the terminals inside the connector boot (Fig. 24).
(4) Close all doors, windows and vents to the passen-
ger compartment. (5) Set heater-A/C control to A/C, full heat, FLOOR,
and high blower. (6) Start the engine and hold the idle speed (1000
rpm). After the engine has reached running tempera-
ture, allow the passenger compartment to heat up.
This will create the need for maximum refrigerant flow
into the evaporator. (7) Discharge (high pressure) gauge should read 965
to 1655 kPa (140 to 240 psi) when the refrigerant
charge is sufficient. If system cannot achieve proper
pressure, replace the expansion valve. If pressure is
correct, record reading and proceed with test.
WARNING: PROTECT SKIN AND EYES FROM CON-
TACTING CO
2PERSONAL INJURY CAN RESULT.
(8) If discharge pressure is within specified range,
freeze the expansion valve control head (Fig. 8) for
30 seconds. Use a super cold substance (liquid
CO
2). Do not spray R-12 Refrigerant on the expan-
sion valve for this test. Refer to Refrigerant
Recycling in the Refrigerant Service Procedures
section. If compressor discharge (high) pressure does
not drop by 15% or more than the pressure recorded in
step 7, replace the expansion valve. Allow the expan-
sion valve to thaw. The discharge pressure should
Fig. 22 Low Pressure Cut-Off Switch and Expansion ValveÐTypical
Fig. 23 Differential Pressure Cut-Off Switch and Ex-pansion ValveÐTypical
Fig. 24 Differential Pressure Cut-Out Switch
Ä HEATING AND AIR CONDITIONING 24 - 55

stabilize to the pressure recorded in step 7. If the
pressure does not stabilize, replace the expansion
valve.When expansion valve tests are complete, refer to
Heater and A/C Performance Tests and remove all test
equipment before returning vehicle to use.
SILVER EXPANSION VALVE TEST
Expansion valve tests should be performed af-
ter compressor tests. Liquid CO
2is required to test the expansion
valve. It is available from most welding supply
facilities. CO
2is also available from companies
which service and sell fire extinguishers. Review Safety Precautions and Warnings in the
General Information section of this Group. The work
area and vehicle must be 21ÉC to 27ÉC (70ÉF to 85ÉF)
when testing expansion valve. To test the expansion
valve: (1) Connect a charging station or manifold gauge set
to the refrigerant system service ports. (2) Verify the refrigerant charge level using the sight
glass method. (3) Disconnect wire connector at low pressure cut-off
switch (Fig. 25). Using a jumper wire, jump terminals
inside wire connector boot.
(4) Close all doors, windows and vents to the passen-
ger compartment. (5) Set heater-A/C control to A/C, full heat, FLOOR,
and high blower. (6) Start the engine and hold the idle speed (1000
rpm). After the engine has reached running tempera-
ture, allow the passenger compartment to heat up.
This will create the need for maximum refrigerant flow
into the evaporator. (7) If the refrigerant charge is sufficient, discharge
(high pressure) gauge should read 965 to 1655 kPa (140
to 240 psi). Suction (low pressure) gauge should read
140 kPa to 207 kpa (20 psi to 30 psi). If system cannot achieve proper pressure readings, replace the
expansion valve. If pressure is correct, proceed with
test.
WARNING: PROTECT SKIN AND EYES FROM CON-
TACTING CO
2PERSONAL INJURY CAN RESULT.
(8) If suction side low pressure is within specified
range, freeze the expansion valve control head (Fig. 26)
for 30 seconds. Use a super cold substance (liquid CO
2).
Do not spray R-12 Refrigerant on the expansion
valve for this test. Suction side low pressure should
drop to -50 kPa (-15 in. Hg) If not, replace expansion
valve.
(9) Allow expansion valve to thaw. The low pressure
gauge reading should stabilize at 140 kPa to 240 kPa
(20 psi to 30 psi). If not, replace expansion valve. When expansion valve test is complete, test A/C
overall performance. Refer to the Heater and A/C
Performance Test in this section. Remove all test
equipment before returning vehicle to use.
REMOVAL
WARNING: THE REFRIGERATION SYSTEM MUST BE
COMPLETELY EMPTY BEFORE PROCEEDING WITH
THIS OPERATION.
(1) Remove the boot-type wire connector from the
pressure cut-off switch. (2) Remove the attaching bolt in center of refriger-
ant line-plumbing sealing plate (Fig. 27). (3) Carefully pull the refrigerant line-sealing plate
assembly from the expansion valve towards front of
vehicle. Do Not scratch the expansion valve sealing
surfaces with pilot tubes. (4) Cover the openings on A/C line-sealing plate
assembly to prevent contamination. (5) Remove two screws securing the expansion valve
to the evaporator sealing plate. (6) Carefully remove valve.
Fig. 25 Low Pressure Cut-Off Switch
Fig. 26 Expansion Valve
24 - 56 HEATING AND AIR CONDITIONING Ä

INSTALLATION
(1) Remove and replace the aluminum gasket on
the evaporator sealing plate. (2) Carefully hold the expansion valve to the evap-
orator sealing plate (do not scratch sealing surface).
Install two attaching screws and tighten to 11 63
N Im (100 630 inch lbs.).
(3) Remove and replace the aluminum gasket (Fig.
15) on the refrigerant line-sealing plate assembly. (4) Carefully hold the refrigerant line-sealing plate
assembly to the expansion valve, install bolt and
tighten to 23 63N Im (200 630 inch lbs.).
(5) Connect wires to low pressure cut-off switch.
(6) Evacuate and recharge system.
(7) After expansion valve is installed, system is
charged, and leaks have been checked, repeat A/C
performance check.
FILTER-DRIER ASSEMBLY
REMOVAL AND INSTALLATION
WARNING: THE REFRIGERATION SYSTEM MUST
BE COMPLETELY EMPTY BEFORE PROCEEDING
WITH THIS OPERATION.
(1) Remove the two high pressure lines from the
sides of the filter-drier assembly (Fig. 1). Then care-
fully separate the lines from filter-drier. Discard old
gaskets. (2) Cover the open ends of the A/C lines to mini-
mize system contamination. (3) Remove two mounting strap bolts and lift the
filter-drier from vehicle. If replacing the filter-drier
assembly, transfer the mounting strap to replace-
ment part. To install, replace both refrigerant line to filter-
drier gaskets, and reverse the preceding operation. Evacuate and recharge system.
CONDENSER ASSEMBLY
The A/C condenser is mounted to the radiator with
bolts (upper) and mounting pads (lower).
WARNING: THE REFRIGERATION SYSTEM MUST BE
COMPLETELY REMOVED BEFORE PROCEEDING
WITH THIS OPERATION. REFER TO DISCHARGING
REFRIGERATION SYSTEM IN THIS GROUP.
REMOVAL AND INSTALLATION
(1) Using a refrigerant recovery machine, remove
the refrigerant from the A/C system. (2) Remove the refrigerant line mounting nut (Fig.
2) and separate the refrigerant lines from condenser
sealing plate. (3) Cover the open ends of the A/C lines and con-
denser to minimize system contamination. (4) Remove the coolant overflow bottle, electric cool-
ing fans and radiator assembly. Also remove the turbo-
charger inter-cooler if equipped. Refer to Group 7,
Cooling System. On some models, complete removal of the ra-
diator, or coolant drainage is not necessary. The
radiator may be moved slightly rearward to re-
move the condenser. (5) Remove the two bolts securing the condenser
assembly to the radiator. (6) Slip the condenser from the lower radiator
mounting brackets. (7) Remove condenser.
To install, replace all O-rings and gaskets and coat
sealing surfaces with approved refrigerant oil. Then
reverse the preceding operation. When installing a
Fig. 27 Expansion Valve
Fig. 1 Filter-DrierÐTypical
Ä HEATING AND AIR CONDITIONING 24 - 57

new condenser, refer to Oil Level in the Refrigerant
section. Tighten the refrigerant line mounting nut to
23 N Im (200 inch pounds).
Evacuate and recharge system.
BLOWER MOTOR
BLOWER MOTOR VIBRATION AND/OR NOISE DIAGNOSIS
The resistor block (Fig. 3), supplies the blower mo-
tor with varied voltage (low and middle speeds) or
battery voltage (high speed).
CAUTION: Stay clear of the blower motor and resis-
tor block (Hot). Do not operate the blower motor
with the resistor block removed from the heater-A/C
housing. Refer to the Blower Motor Vibration/Noise chart in
this section for diagnosis.
BLOWER MOTOR ELECTRICAL DIAGNOSIS
Refer to the Blower Motor Electrical System Diag-
nosis chart in this section. Also refer to Group 8W,
Wiring Diagrams for more information.
REMOVAL AND INSTALLATION
(1) Disconnect the negative battery cable.
(2) Remove the glove box. Refer to Group 8E, In-
strument Panel. (3) On vehicles equipped with A/C, disconnect the
two vacuum lines from the recirculating air door actuator. Dis-
connect blower lead wire connector. (4) Remove two screws at the top of the blower
housing, securing it to the unit cover. (5) Remove five screws from around the blower
housing and separate the blower housing from the
unit (Fig. 4). (6) Remove three screws securing the blower and
wheel assembly to the heater or A/C unit housing.
Then separate the assembly from the unit (Fig. 5). To install, reverse the preceding operation.
BLOWER MOTOR WHEEL ASSEMBLY
REMOVAL AND INSTALLATION
Blower motor must be removed from vehicle before
performing this operation. Refer to Blower Motor Re-
moval and Installation. (1) Remove the spring type retaining ring from the
center of the blower wheel (Fig. 6). Note the location
of the blower wheel on the blower motor shaft. (2) Remove blower wheel from blower motor shaft.
To install, reverse the preceding operation. To pre-
vent noise or vibration, rotate the blower wheel by
hand to check for rubbing.
Fig. 2 A/C Condenser Refrigerant LinesÐTypical
Fig. 3 Blower Motor Resistor BlockÐTypical
Fig. 4 Blower HousingÐTypical
24 - 58 HEATING AND AIR CONDITIONING Ä

BLOWER MOTOR NOISE/VIBRATION DIAGNOSIS
Ä HEATING AND AIR CONDITIONING 24 - 59

BLOWER MOTOR ELECTRICAL SYSTEM DIAGNOSIS
24 - 60 HEATING AND AIR CONDITIONING Ä

HEATER-A/C UNIT ASSEMBLYÐREMOVAL AND
INSTALLATION
AP, AC, AY BODY PROCEDURE
WARNING: IF EQUIPPED WITH A/C, THE REFRIG-
ERATION SYSTEM MUST BE COMPLETELY EMPTY
BEFORE PROCEEDING WITH THIS OPERATION.
(1) Disconnect battery NEGATIVE cable.
(2) Drain radiator and disconnect heater hoses at
unit. Tape heater tubes to keep from leaking during
removal. Refer to Group 7, Cooling System. (3) Remove A/C condensate drain and disconnect
vacuum lines. (4) Inside passenger compartment, perform as fol-
lows, according to body designation. (a) AC-body, remove right upper and lower un-
der-panel silencers. (b) AP & AC-bodies, remove steering column
cover. (c) AC-body, remove left under-panel silencer.
(5) Position front seat or right front seat full rear. (a) AP-body, remove right A-pillar trim.
(b) Remove right cowl side trim.
(6) Remove glove box. (a) AC-body, remove right instrument panel re-
inforcement.
(7) AP-body only: (a) Remove right instrument panel lower mount-
ing screw. (b) Remove center bezel.
(c) Remove lower center module cover.
(d) Remove floor console.
(e) Remove instrument panel support brace (from
steering column opening to right cowl side at bot-
tom of instrument panel). (f) Remove instrument panel to support bracket
(below glove box opening). (g) Remove ash receiver.
(h) Remove radio.
(i) Remove panel top cover.
(j) Remove three right side panel to fence (below
windshield) attaching screws.
(8) AC-body, remove ash receiver.
(9) AP body, pull right lower side of instrument
panel rearward. (10) Remove center distribution and defroster
adapter ducts. (11) AP and AC-bodies, disconnect relay module.
(12) AP-body, remove instrument panel to unit
bracket. (13) AP-body, remove lower air distribution duct.
(14) Disconnect blower motor wire connector.
(15) Disconnect demister hoses from top of unit.
(16) For Non-ATC equipped vehicles, disconnect
the temperature control cable flag from the bottom of
the heater-A/C unit. Then un-clip the cable from the
left side of the heat distribution duct. Swing the ca-
ble out of the way to the left. Disconnect the vacuum
lines at the unit. (17) For ATC equipped vehicles, disconnect the in-
strument panel wiring from the rear face of the ATC
control unit. (18) AC body, disconnect right 25-way connector
bracket and fuse block from panel. (19) Fold floor right side carpet back (except AC
body). (20) From engine compartment, remove four unit
attaching nuts. (21) Remove unit hanger strap lower screw, and
rotate strap. (22) Move heater-A/C unit rearward to clear
mounting studs, and lower unit. (23) AP-body, remove demister adapter from top of
unit. (24) While pulling the lower right of instrument
panel rearward: (a) Slide unit upright from under instrument
panel for AP-body. (b) Except for AP-body, rotate unit while pulling
from under instrument panel.
To install, reverse the preceding operation.
Fig. 5 Blower Motor and Wheel Assembly
Fig. 6 Blower Wheel Retaining Ring Removal and Installation
Ä HEATING AND AIR CONDITIONING 24 - 61

AA BODY PROCEDURE
WARNING: IF EQUIPPED WITH A/C, THE REFRIG-
ERATION SYSTEM MUST BE COMPLETELY EMPTY
BEFORE PROCEEDING WITH THIS OPERATION. Refer to Group 8E and Group 23 for component re-
moval and installation when performing this opera-
tion. (1) Perform steps 1 through 7 of Blower Motor re-
moval and installation. (2) Remove relay panel above glove compartment
opening. (3) Disconnect the A/C vacuum line connector and
radio noise capacitor connectors. (4) Remove left windshield pillar trim cover.
(5) Remove left lower side cowl trim cover.
(6) Remove hood release handle mechanism attach-
ing screws. (7) Remove steering column trim covers.
(8) Disconnect parking brake release mechanism
connecting rod. Gain access through fuse panel open-
ing. (9) Remove lower left instrument panel silencer.
(10) Remove lower left instrument panel reinforce-
ment. (11) Remove instrument panel center (radio) bezel.
(12) Remove forward floor console.
(13) Remove the radio.
(14) Remove the heater-A/C control.
(15) Remove cigar lighter.
(16) Remove message center/trip computer, if
equipped. (17) Disconnect side window demister tubes from
top of heat A/C unit. (18) Remove steering column upper attaching bolts
and allow the steering wheel to rest on the driver
seat cushion. (19) Remove upper instrument panel (defroster
outlet) cover. (20) Remove upper instrument panel attaching
screws from below the windshield opening. (21) Loosen (do not remove) the left lower cowl in-
strument panel attaching screw. (22) Remove the right lower cowl instrument panel
attaching screw.
CAUTION: Protect the passenger seat cover from
soiling or damage using a suitable cover.
(23) Carefully pull the right side of the instrument
panel away from the vehicle. Allow the instrument
panel to rest on the passenger seat cushion.
CAUTION: Before proceeding with the next opera-
tion, review the Safety Precautions and Warnings at
the front of this Group. (24) From the engine compartment, drain the cool-
ing system and disconnect the heater hoses from the
heater core nipples. Plug the nipples to avoid spilling
coolant inside the vehicle. (25) Disconnect the refrigerant lines from the ex-
pansion-valve at the dash panel on the right side of
the vehicle. Seal the refrigerant lines to prevent con-
tamination. (26) Remove the expansion valve from the evapo-
rator plate. Seal the valve to avoid contamination. (27) Remove the condensate drain tube.
(28) Remove heater-A/C unit to dash panel attach-
ing nuts. (29) From inside the vehicle, pull rearward on the
heater-A/C unit to clear the dash panel silencer and
remove the unit from the vehicle. To install, reverse the preceding operation. Refill
cooling system and test for leaks. Evacuate and
charge the refrigerant system and test overall perfor-
mance.
AG, AJ BODY PROCEDURE
WARNING: IF EQUIPPED WITH A/C, THE REFRIG-
ERATION SYSTEM MUST BE COMPLETELY EMPTY
BEFORE PROCEEDING WITH THIS OPERATION.
(1) Disconnect the battery negative cable.
(2) Drain the coolant from cooling system. Refer to
Group 7, Cooling System. (3) Remove the air conditioner expansion valve (if
equipped). (4) Disconnect the heater hoses from heater core.
Then plug or cap the tubes on heater core. This will
prevent spilling coolant into the interior of vehicle
during unit removal. (5) Remove the condensate drain tube.
(6) Disconnect the A/C-heater vacuum supply line
from vacuum supply nipple (in the engine compart-
ment). (7) Remove the four A/C-heater assembly-to-dash
panel attaching nuts. (8) Remove the passenger side front seat. Refer to
Group 23, Body. (9) Remove the kick panel/sill cover at right door
opening. (10) Remove the body computer (Fig. 6) located at
the lower right section of the right front door pillar. (11) Remove the glove box assembly. Refer to
Group 8E, Instrument Panel. (12) Remove the carpeted panels from both sides of
the console. (13) Un-clip the radio antenna cable from the
metal support (Fig. 6) located behind and below the
glove box opening. (14) Instrument panel removal is not necessary to
remove the A/C-heater assembly from the vehicle.
24 - 62 HEATING AND AIR CONDITIONING Ä

Although, part of the lower instrument panel must
be cut. The cut line is marked: CUT HERE FOR
A/C HTR REMOVAL. This cut line is stamped (indented) into the right-
outer side of the instrument panel padding (outboard
of the glove box opening). Using a hacksaw blade,
cut the instrument panel padding along the indented
line from point A to point B (Fig. 7). CUT THE
PLASTIC ONLY . Do not cut the metal support be-
hind the instrument panel padding.
(15) Remove the metal support behind and below
the glove box opening, and the previously cut piece of
the instrument panel that is riveted to it. (16) Remove the radio choke, security alarm mod-
ule and the lamp outage module from above the
glove box opening (if equipped). (17) Remove the plastic cover under the steering
column. (18) Remove the metal support under the steering
column. (19) AJ Body only: Remove the under-panel si-
lencer pad from under the glove box opening. (20) Remove the lower heat distribution duct (3
screws). (21) Remove the air distribution duct through the
opening at the left side of instrument panel. (22) Reach through glove box opening and discon-
nect the demister hoses from the top of the A/C-heat-
er assembly. (23) Disconnect the temperature control cable from
the bottom of the A/C-heater assembly and position
out of the way. (24) Disconnect wiring at the blower motor and
fin-sensing cycling clutch switch electrical connectors. (25) Un-plug the antenna cable from the radio.
(26) Remove the metal (A/C-heater-to-instrument
panel) hanger strap from the upper part of the A/C-
heater assembly. (27) Roll back the floor carpeting from under the
A/C-heater assembly far enough to avoid restricting
unit removal. (28) Remove the A/C-heater assembly through the
opening on the right side of the console, and remove
unit from vehicle. The instrument panel (to the left side of the glove box
opening) must be slightly folded back to remove the
unit from the vehicle. If wrinkles appear in the instru-
ment panel after the unit has been installed, they may
be removed using a heat gun. Refer to Installation AG,
AJ Body for instructions. To install, reverse steps (28) through (13). If wrinkles
have appeared in the instrument panel, apply low heat
from a heat gun over the wrinkled area. Do not
overheat the instrument panel padding or the
surrounding area. Reverse steps (12) through (1). If equipped with A/C,
evacuate and charge the refrigerant system.
HEATER-A/C UNIT RECONDITION
The following operation requires the removal of the
heater-A/C unit assembly from the vehicle. Refer to
Heater-A/C Unit Assembly removal and installation in
this Group.
DISASSEMBLE
(1) Place the heater-A/C unit on a suitable work
surface. (Fig. 1).
(2) Locate and remove one retaining nut from the
blend-air door pivot shaft.
Fig. 7 Cut Line For A/C-heater RemovalÐAG/AJ Body
Fig. 1 Position Heater-A/C Unit for Disassembly andReassembly
Ä HEATING AND AIR CONDITIONING 24 - 63

(3) To remove the top cover from the A/C-heater
case, the crank arm must be removed (Fig. 2).
(4) Disconnect the vacuum lines from the defroster
and panel mode vacuum actuators and position them
out of the way. (5) Remove three heater-A/C unit cover attaching
screws going upward at the defroster outlet chamber. (6) Remove two heater-A/C unit cover attaching
screws going upward at the air inlet plenum. (7) Remove eleven heater-A/C unit cover attaching
screws going downward into the housing. Then lift
the cover from the heater-A/C unit. (Fig. 3).
To reassemble, lower the heater-A/C unit cover
into place. Then guide the panel air mode door pivot
shaft into its socket and reverse the preceding oper-
ation.BLEND-AIR DOOR
REMOVAL AND INSTALLATION
The following operation requires the removal of the
heater-A/C unit assembly from the vehicle. Refer to
Heater-A/C Unit Assembly removal and installation
in this Group. (1) Remove Heater-A/C unit top cover.
(2) Remove the nut from bottom of the blend-air
door pivot shaft and lift the blend-air door from the
heater-A/C unit housing. (Fig. 4).
To install, reverse the preceding operation.
HEATER CORE
REMOVAL AND INSTALLATION
Refer to Heater A/C Unit Recondition in this
Group.
EVAPORATOR COIL
REMOVAL AND INSTALLATION
Refer to Heater A/C Unit Recondition in this
Group.
CONDENSATE DRAIN TUBE
Condensation that accumulates on the bottom of
the evaporator housing is drained from a rubber tube
through the dash panel and on to the ground. This
tube must be kept open to prevent condensate water
from collecting in the bottom of the heater A/C unit
housing. The tapered end of the drain tube is designed to
keep contaminants from entering the heater A/C unit
housing. If the tube is pinched or blocked, condensate
cannot drain, causing water to back up and spill into
Fig. 2 Blend-Air Door Crank Linkage Removal
Fig. 3 Heater-A/C Unit Cover Removal and Installation
Fig. 4 Blend-Air Door Removal and Installation
24 - 64 HEATING AND AIR CONDITIONING Ä