Chevrolet 10 1971 Series Chassis Service Manual page 55

EVAPORATOR CORE (Fig. 52)
Removal
1. Disconnect the battery ground cable.
2. Purge the system of refrigerant.
3. Remove the rear duct as outlined previously.
4. Disconnect the blower motor leads, ground wire,
thermostatic switch and relay connections and the
thermostatic switch sensing line.
5. Disconnect the refrigerant lines at the rear of the
blower-evaporator assembly.
6. Remove the blower-evaporator to roof panel attach­
ments and lower the blower-evaporator assembly far
enough to disconnect the resistor wiring harness.
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 tape 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 core and
insert the plastic pins.
2. Install the expansion valve inlet, outlet and external
lines using new "O" rings coated with clean refrig­
eration oil. Install the sensing bulbs to the evapora­
tor outlet line as shown in Figure 51, make sure the
bulbs have good contact with the line.
Add 3 oz. clean refrigeration oil when
NOTE:
installing a new core.
3. Install the upper case and upper shroud to the core.
Install the thermostatic switch sensing capillary into
the plastic clips at the front of the core.
4. Install the lower core case and blower assemblies.
5. Install the blower-evaporator to the roof panel, first
connecting the resistor wires.
6. Connect the refrigerant lines to the blower-evaporator
Fig. 5 2 — Evaporator Core Installation
C O R E M O U N T IN G
BO LTS
L O W E R C O R E C A S E
HEATER AND AIR CONDITIONING 1A-37
unit using new "O" rings coated with clean refrigera­
tion oil.
7. Connect the blower lead wires, ground strap, thermo­
static switch and relay harnesses.
8. Install the rear duct as outlined previously.
9. Connect the battery ground cable.
10. Evacuate, charge and performance test the system.
MUFFLER A N D CONNECTOR BLOCK
Removal (Fig. 53)
1. Purge the system.
2. Remove hoses at the compressor inlet and muffler
outlet pipes. Cap the connections.
Remove muffler outlet pipe clamp.
3.
Remove bolt retaining connector block to compressor
4 .
and remove the connector and muffler assembly. Cap
the compressor ports if not immediately remounting
muffler assembly.
Installation
1. Assemble the connector block to the compressor
using new "O" ring seals wetted with clean refrigera­
tion oil.
2. Secure the muffler outlet pipe in the pipe clamp.
Connect the refrigerant hoses to the compressor in­
3.
let and muffler outlet pipes.
Evacuate and recharge the system.
4 .
ANTI-DIESELING RELAY
This relay is mounted to the instrument panel, just to
the left of the heater control. Its purpose is to actuate
the compressor clutch when the ignition switch is turned
off.
Replacement (Fig. 54)
1. Disconnect the electrical connector at the relay.
2. Remove the relay to instrument panel attaching
screw and remove the relay.
Place the new relay in position (tang in hole in
3.
instrument panel) and install the mounting screw.
Connect the wiring harness.
4 .
Fig. 5 3 — Compressor Connector Block and M uffler
10-30 CHEVROLET TRUCK SERVICE MANUAL