Chevrolet Light Duty Truck 1973, Service Manual

Page: 101 / 979

HEATER A N D AIR C O N D I T I O N I N G 1A-75
EVAPORATOR CORE (Fig. 90)
1. Disconnect the battery ground cable and compres­
sor clutch connector.
2. Purge the system of refrigerant.
3. Remove the rear shroud as outlined previously.
4. Disconnect the blower motor leads and ground
7.
9.
10 .
Connect the blower lead wires and ground straps.
Install the rear shroud as outlined previously.
Connect the battery ground cable and the
compressor clutch connector.
Evacuate, charge and check the system.
wire.
5. Disconnect the refrigerant lines at the rear of the
blower-evaporator assembly. Cap or plug open
connections at once.
WARNING:
Before removing the blower-
evaporator unit, support the case to prevent
damage to components.
RESISTOR
See Electrical Components in the Floor Mounted System
Section of this manaul (fig. 80).
BLOWER SWITCH
See Blower Switch in the Floor Mounted System Section
of this manual (fig. 80).
REAR BLOWER RELAY
The rear blower relay is attached to the instrument panel
reinforcement, just left of the steering column (fig. 91).
Replacement
1. Disconnect battery ground cable.
Disconnect relay wiring harness at the relay.
Remove the relay attaching screw and remove the
relay.
To install, reverse Steps 1-3 above. Check system
operation.
2
.
3.
4.
TIE RELAY
See Electrical Components in the Floor Mounted System
Section of this manual (fig. 80).
6. Remove the blower-evaporator to roof panel
attachments and lower the blower-evaporator
assembly. Remove the assembly and place it on a
work bench upside down.
7. Remove the lower to upper case screws and remove
the lower case assembly. Remove the upper shroud
and upper case from the evaporator core.
8. Remove the expansion valve inlet and outlet lines
and cap or plug the open connections at once.
Remove the expansion valve capillary bulbs from
the evaporator outlet line and remove the valves.
9. Remove the plastic pins holding the screen to the
core and remove the screen.
Installation
1. Install the wire screen to the front of the new core
and insert the plastic pins.
2. Install the expansion valve inlet and outlet lines
using new "O" rings coated with clean refrigeration
oil. Install the sensing bulbs to the evaporator outlet
line. Make sure the bulbs have good contact with
the line.
NOTE: Add 3 oz. clean refrigeration oil
when installing a new core.
3. Install the upper case and upper shroud to the core.
4. Install the lower core case and blower assemblies.
5. Install the blower-evaporator to the roof panel.
6. Connect the refrigerant lines to the blower-
evaporator unit using new "O " rings coated with
clean refrigeration oil.
C O M P O N E N T PART REPLACEMENT
DASH M O U N TE D S Y S TE M -M O TO R HO M E CHASSIS
CONDENSER
Replacement
1. Disconnect the battery ground cable.
This system is installed on the vehicle and checked at
assembly. The blower-evaporator is then disconnected
and shipped with the chassis unit to the body supplier.
For this reason, it will only be possible to give basic
replacement procedures on some components.
LIGHT DUTY TRUCK SERVICE MANUAL