
HEATER AND AIR CONDITIONING 1A-50
Fig.
64—Receiver-Dehydrator Mounting (Corvette)
3.
4.
5.
6.
To gain access to the blower motor end of the as-
sembly, remove the fender and skirt.
Remove the assembly to firewall attaching screws.
Remove the entire assembly from the vehicle.
Reverse the above procedure when installing the
assembly into the vehicle.
Core Replacement
1.
Disconnect the connections at the suction throttling
valve inlet and the expansion valve outlet. Remove
the expansion valve bulb from the core outlet line.
Cap all open lines. .
Remove the screws attaching the evaporator cover
to the firewall and to the evaporator assembly and
remove the cover.
Remove the screws attaching the core to the assem-
bly and remove the core.
Reverse the above steps for core replacement.
Add three fluid oz. refrigerant after installing a
new core, evacuate and charge the system.
2.
3.
4.
5.
Comfortron
The evaporator assembly is nearly identical to that
of the Four-Season system, and, with the exception of
additional wiring and vacuum hoses, service procedures
are the same.
Chevelle Four-Season System
Removal
•
1.
Purge the system of refrigerant, then remove the
right fender skirt and the hood hinge. Do not remove
the fender.
2.
Disconnect the high pressure line (between the
receiver-dehydrator and the thermostatic expansion
valve) at the expansion valve, and the suction throt-
tling valve to compressor line at the suction throt-
tling valve. Cap and seal all open lines.
3.
Remove the three screws attaching the duct assembly
to the evaporator housing and the blower assembly.
4.
Remove the bolts attaching the evaporator assembly
to the cowl and carefully pull the assembly from the
vehicle. The duct assembly will be removed at this
time also.
Core Replacement
1.
With the evaporator assembly removed from the
vehicle, remove the expansion valve and its bulb.
2.
Remove the four nuts and bolts holding the two
halves of the evaporator housing together and sepa-
rate the halves.
3.
The evaporator core may now be removed.
4.
Leak test the new core and connections, before in-
stalling the core in the housing, by installing the
expansion valve and all refrigerant lines. Connect an
R-12 cylinder to the low pressure compressor gauge
fitting and charge the system to cylinder pressure,
then leak test.
5. After satisfactorily testing the core, install it into
the housing and reassemble the two sides of the.
housing.
Installation
1.
Remove the right trim pad and the screws attaching
the air conditioning duct to the kick panel. This
should allow the duct to be pulled slightly loose from
the kick panel. If not it may be necessary to loosen
the entire duct to obtain the necessary clearance.
2.
Install the evaporator in the cowl being sure that
the duct assembly is in place between an evaporator
housing and the blower assembly.
3.
Replace all bolts and screws.
4.
Move the interior air conditioning duct until sure
that the duct gasket is properly positioned over the
evaporator housing flange. Proper gasket fit at this
point is of great importance.
5. Replace all refrigerant lines.
6. Evacuate and charge the system. Add three fluid oz.
refrigerant oil after installing a new core.
7. Replace the fender skirt and hood hinge.
Universal System All Vehicles
Core and/or Expansion Valve Replacement
Since repairs should never be made on the evaporator
core, a defective unit must be replaced. Before replacing
the core, however, check to be sure that any leaks pres-
ent are not located at the hose connections or expansion
valve connections.
CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-52
Fig.
68—Wiring and Vacuum Lines—Four-Season (Chevrolet)
Fig.
69-Underhood Wiring-Four-Season (Chevelle)
CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-53
Fig.
70—Wiring and Vacuum Lines—Four-Season (Camaro)
Installation
1.
Connect the expansion valve to the refrigerant pipes.
Attach the capillary bulb to the evaporator.
2.
Attach the evaporator to the- case. Attach the inlet
and outlet pipes clamps.
3.
Assemble the case halves. Insert the capillary tube
from the thermostatic switch between the fins as
shown in Figure . Attach the cover plate to the
case.
4.
Mount the unit to the dash and connect the refrigerant
lines.
5.
Evacuate and charge the system. If a new evaporator
was installed, add three fluid ounces of refrigerant
oil to the system before charging.
6. Test system operation.
Chevy II All-Weather System
Removal
Under
the Hood
1.
Purge the refrigerant from the system.
2.
Remove the refrigerant hoses from the evaporator
inlet and outlet connections extending through the
special grommet in the dash panel and into the
engine compartment.
3.
Remove the screw, nut, spacer bracket and grommet
from the outlet connection pipes.
Within the Car
4.
Remove the glove box, ash tray and ash tray
retainer.
5.
Reach through the glove box door to disconnect the
air conditioning "on" door bowden cable (fig. 75).
6. Remove the two shield attaching screws and shield
(A, fig. 76) which covers the lower right evaporator
bracket-to-blower bracket attaching screw (B, fig.
76),
then remove this screw.
7.
Behind the lower left side of ihe evaporator, remove
the evaporator bracket-to-heater distributor bracket
attaching screw (C, fig. 76).
8. Reaching through the glove box door and ash tray
openings, remove the two nuts and washers (D,
fig.
76) attaching the evaporator assembly studs to
the lower instrument panel flange and reinforcement.
9. Disconnect the drain hoses and carefully pull the
evaporator unit toward the rear of the vehicle.
10.
Disconnect wiring connectors (see fig. 77) as nec-
essary and remove the evaporator unit from the
vehicle.
Gore and/or Expansion Valve Replacement
A defective unit must be replaced since repairs should
never be made on the evaporator core. Before replacing
the core, however, check to be sure that any leaks pres-
sent are not located at the hose connections or expansion
valve connections. The following procedure assumes that
the evaporator unit has been removed from the vehicle
as outlined above.
CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-54
Fig.
71-Wiring-AH Weather (Chevy II)
1.
Loosen the lock screws and remove the two control
knobs from the front of the evaporator unit. Then
use a suitable spanner wrench to remove the two
nuts beneath the control knobs.
2.
Remove the screws (located in the outer ball outlets)
attaching the face plate.to the evaporator case. Then
remove the face plate and, reaching through this
opening, carefully remove the plug attaching the
thermostatic switch capillary tube to the evaporator
core.
3.
Turning the unit over, remove the screws attaching
the back cover and gasket to the case and remove
the cover and gasket.
4.
From the top of the case, remove the screws attach-
ing the evaporator core brackets to the case.
5.
Carefully draw the core and expansion valve assem-
bly out of the case.
NOTE: The air conditioning "on" door bowden
cable, which extends through the core, will also
be removed at this time.
6. Remove the expansion valve power element from
the low pressure line.
7.
Disconnecting the high pressure and low pressure
lines from the valve, remove the valve from the
core.
8. At this point either the expansion valve, evaporator
core or both may be replaced.
a. If replacing the expansion valve, use new etO"
rings and make the connections carefully to
eliminate possible refrigerant leaks. Position
the power element bulb so that it lies flush with
the low pressure line and has the insulating
material properly in place.
b.
If the evaporator core is to be replaced, it will
be necessary to remove the air conditioning
door bowden cable from the core and install it
in the same location in the replacement core.
If no passage has been provided for this purpose
in the replacement core, a pointed instrument
such as a pencil may be forced through core
vanes at the proper location to provide the re-
quired opening. Also remove the spacer bracket,
nut and screw from the inlet and outlet pipes of
the evaporator core and place them in a like
position on the replacement core.
CHEVROLET CHASSIS SERVICE MANUAL

HEATER
AND AIR
CONDITIONING
1A-55
r-TO COMPRESSOR
^GROMMET^-^^Q^S
L.H. REAR—>*<^ >
BRACKET
/>v\j^-""^
A
r—FORWARD
\ BRACKET
*-^"^
\
EVAPORATOR
BLOWER
ASM
\
-BRACE
===:
7—-INSTRUMENT PANEL
f REINFORCEMENT
/
/
f
R.H. REAR
M
BRACKET
m
K BRACKET—^
#INLET
V
M
"6"
RING
\
/
\N
1
-
DASH PANEL—v
GROMMET—^
\
OUTLET—v
A^
J/
X
\—
OUTLET
"O"
RING
A \~-EVAPORATOR
,
&
BLOWER
ASM
INLET
TUBE
Fig.
72—Evaporator Mounting—Universal Unit
9. Replace
the
core
and
valve assembly, with
the
bow-
den cable
in
place,
in the
evaporator case
and
install
the
two
case-to-door bracket attaching screws.
10.
With
the
gasket
in
place, install
the
back cover
of
the evaporator case
and its
attaching screws and
the
seal around
the
evaporator inlet
and
outlet tubes.
11.
Reach through
the
face plate opening
and,
using
the
plastic plug, attach
the
thermostatic switch capillary
tube
to the
evaporator core.
Installation
Within
the Car
1.
Attach system wiring
as
necessary
to the
evaporator
case.
2.
Carefully pass
the
evaporator inlet
and
outlet pipes
through
the
special grommet
in the
dash panel.
3.
Insert
the
evaporator studs through their drilled
holes
in
the
instrument panel flange
and
reinforce-
ment
and,
reaching through
the
glove
box
door
and
ash tray opening, install
the nut
and washer
on
each
stud.
4.
Replace
the
screws attaching
the two
evaporator
case brackets
to
the
blower bracket and distributor
bracket.
5. Replace
the
shield
and
attaching screws protecting
the lower right mounting bracket.
6. Reaching through
the
face plate opening, attach
the
evaporator bowden cable.
7. Replace
the
face plate and attaching screws, feeding
the control knob stems through
the
proper openings
in
the
face plate.
8. Replace
the
control stem bezels
and
control knobs.
9. Replace
the
drain hoses.
10.
Replace
the
glove
box
and
ash
tray.
Under
the
Hood
11.
Replace
the
spacer bracket, screw
and nut on the
CHEVROLET CHASSIS SERVICE /MANUAL

HEATER AND AIR CONDITIONING 1A-56
BLACK & RED
IGNITION—-y^****
SWITCH -"A
/
BLOWER LEAD—^^^
RESISTOR—-" \^<
ASM.
f'
i
'fu^^^^A^^^^^r"G^OUH£>
WIRE
^^
k4
^EVAPORATOR HARNESS
' EVAPORATOR & BLOWER ASM.
Fig.
73—Underdash Wiring—Universal System (Typical)
evaporator outlet pipes. Locate the bracket about
1/2" from the dash panel.
12.
Replace the inlet and outlet hoses and hose clamp
connections.
13.
Evacuate and charge the system. Add three fluid oz.
refrigerent oil after installing a new core.
14.
Check system performance.
Corvette
Replacement (Fig. 78)
1.
Purge the system of refrigerant.
2.
Drain the engine radiator. Then remove the radiator
supply tank from its brackets, the heater water
valve and vacuum line from the firewall, and the
heater hoses from the core pipes. Carefully fold the
hoses,
valve and tank away from the evaporator
case.
3.
Remove the right hand hood lock support.
SCREW DRIVER
(NARROW BLADE) T£
GROOVE
A. Insert screw driver in
tang toward terminal
B. Pry tang back out to
when reinstalled into
RMINAL
\ CONNECTOR
TANG
groove & press
to release.
insure locking
connector.
Fig.
74—Terminal Removal—Universal System
4.
Disconnect the expansion valve equalizer line con-
nection and the evaporator oil bleed line from the
POA.
5.
Disconnect the evaporator outlet to POA inlet
connector.
6. Remove the POA bracket to evaporator case attach-
ing bolts. Then carefully move the valve and its
outlet hose away from the evaporator case.
Fig.
75-Cable Removal-All Weather
CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-58
Fig.
77-Underdash Wiring-All Weather
positioned on the low pressure line, tightly clamped and
has the insulation in place. Make certain the liquid inlet
screen between valve and receiver- dehydrator line is not
clogged. After checking the screen and the location and
mounting of the thermo-bulb, proceed with replacement of
the valve assembly. A malfunctioning valve may result
from a stuck open or shut needle caused by corrosion^ or
a discharged power element caused by a broken capillary
line or tip.
Four-Season System Chevrolet, Chevelle,
Corvette, and Camaro
Replacement
1.
Purge the system and, on Chevelle models, drop
the right fender skirt.
2.
Remove the expansion valve power element bulb
from the low pressure line and the equalizing line
from the POA valve.
3.
Remove the low and high pressure connectors from
the valve, in that order. Remove the screw and
bracket attaching the expansion valve to the blower
case and remove the valve.
4.
Before replacing the valve, check to be certain the
inlet screen, is not clogged. If the screen is plugged,
replace it and check valve operation. If screen is
clear or if valve still malfunctions after screen re-
placement proceed with the valve replacement.
5. Install the new valve by connecting the lines. Clamp
the power element bulb of the new valve to the top of
the low pressure line and the equalizing line to the
suction throttling valve.
NOTE:
Be sure to replace the insulation around
the power element bulb and that the power ele-
ment makes good physical contact with the suc-
tion line.
6. Evacuate and charge the system.
CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-60
Fig.
81-P.O.A. Installation (Camaro)
NOTCH IN SUPPORT
TO ENGAGE SLOT !N VALVE
WHEN VALVE IS ROTATED
TO ANGLE AS SHOWN
Fig.
82-P.O.A. Installation (Chevelle)
Fig.
83—P.O.A. Installation (Corvette)
3.
Remove the electrical connector at the switch to be
replaced.
4.
Remove the switch knob. Remove the switch retain-
ing screws
and:
switch.
Installation
1.
Insert replacement switch into face plate and attach.
2.
Install the switch knob and connect the wiring
connector.
3.
If the thermostatic switch is being replaced, the
capillary tube should be formed to the same shape as
the unit removed.
4.
Attach the capillary to the core (fin sensing type)
and replace the face plate and attaching screws.
CHEVROLET CHASSIS SERVICE MANUAL