GMC 1976 ZEO 6083 Maintenance Manual page 87

1- 70 AIR CONDITIONING SYSTEM
EVAPORATOR AND HEATER
CORE ASSEMBLY
REPLACEMENT (FIGURE 15)
1 . Purge system .
2 . Disconnect air conditioning lines from
evaporator .
3 . Disconnect heater hoses from heater core .
4. Disconnect all vacuum lines, wires and cables
connected to the box assembly .
5 . Remove windshield washer reservoir.
6. Remove coolant recovery reservoir and
bracket .
7 . Disconnect windshield wiper arms .
8 . Remove attaching bolts and remove through
front access door .
9 . To install, reverse steps 1 through 8 .
EVAPORATOR CORE AND
EXPANSION VALVE
REPLACEMENT (FIGURE 15)
CAUTION : When repair or replacement of
the evaporator core or expansion valve is
necessary, be sure to remove both as the
method ofattaching the sensing tube to the
evaporator outlet line will cause it to be da-
maged if you try to remove only one item.
1 . Purge the system of refrigerant .
2. Remove all attaching items to the evaporator
and heater core assembly necessary to remove the
assembly front cover.
3. Remove assembly front cover exposing
evaporator core, expansion valve, thermostat switch,
heater core and selector door .
9$NOT After removing all the cover screws, be sure
to remove the cover retaining clip .
4 . Remove evaporator inlet and outlet hoses.
5. Carefully remove thermostatic switch probe
from front of evaporator held by plastic clips. Do not
bend this tube excessively.
6. Remove four attaching screws and gently pull
out evaporator core .
7. When core and expansion valve are removed
the expansion valve may easily be removed without
damaging the sensing tube .
8. To install, reverse steps 1-7 .
The vacuum tank is mounted to the right side of
the evaporator and heater core assembly (See figure
15).
REPLACEMENT
1 . Disconnect the vacuum lines at the tank .
2. Remove the tank to dash panel screws and
remove the tank .
3 . To install, reverse Steps 1 and 2 above.
BLOWER MOTOR RESISTOR
The blower motor resistor is located opposite the
blower side of the blower-evaporator case (figure 15).
REPLACEMENT
1. Disconnect battery ground cables and the wir-
ing harness at the resistor .
2. Remove the resistor to case attaching screws
and remove the resistor.
VACUUM TANK
3. Place the new resistor in position and install
the attaching screws .
4. Connect the resistor wiring harness battery
cables .
THERMOSTATIC SWITCH (FIGURE
15)
The thermostatic switch is mounted to the
blower side of the blower-evaporator case . The
switch sensing capillary extends across the evapora-
tor core .
REPLACEMENT
1 . Disconnect the battery ground cables .