GMC 1982 Light Duty Truck Service Manual page 75

IB-32 AIR CONDITIONING
Fig. 1 B-25-Checking Evaporator Inlet and Acuumulator Outlet
Temperatures
after above five m inutes of com pressor operation by the
appearance of slow-moving bubbles (vapor) or a broken
column of refrigerant under the glass. C ontinuous bubbles
may appear in a properly charged system on a cool day. This
is a normal situation. If the sight glass is generally clear and
perform an ce is satisfacto ry , occasional bubbles do not
indicate refrigerant shortage.
If the sight glass con sistently shows foam ing or a
broken liquid column, it should be observed after partially
blocking the air to the condenser. If under this condition the
sight glass clears and th e perfo rm an ce is otherw ise
satisfactory, the charge shall be considered adequate.
In all instances where the indications of refrigerant
shortage continues, additional refrigerant should be added
in 120 ml (1 /4 lb.) increm ents until the sight glass is clear.
An additional charge of 240 ml (1 /2 lb.) should be added as
a reserve after the glass clears. In no case should the system
be overcharged.
COMPRESSOR
C-K SERIES
Rem oval (Fig. IB -3 3 )
1. D ischarge the system.
2. Remove connector attach in g bolt and connector. Cap
or plug open connections at once.
3. Disconnect electrical lead to clutch actuating coil.
4. Loosen brace and pivot bolts and detach belt.
5. Remove the nuts and bolts attaching the compressor
brack ets to the m ounting b racket. Rem ove the
compressor.
6. Before beginning any com pressor disassem bly, drain
and m easure oil in the com pressor. Check for evidence
of contam ination to determ ine if rem ainder of system
requires servicing. Com pressor servicing inform ation is
located in the U nit R epair M anual.
Installation
1. If oil previously drained from the com pressor upon
removal shows no evidence of contam ination, replace a
like am o u n t of fresh
compressor before reinstallation. If it was necessary to
refrig eratio n oil into the
service the entire system
contam ination in the oil removed, install a full charge
of fresh refrigeration oil into the compressor.
2. Position com pressor on the m ounting b rack et and
install all nuts, bolts and lock washers.
3. Install the connector assem bly to the com pressor rear
head, using new " O "
refrigeration oil.
4. Connect the electrical lead to the coil and install and
adjust compressor belt.
5. Evacuate, charge and check the system.
G and M otor Hom e Chassis M odels
Rem oval (Fig, IB -2 6 )
1. Disconnect battery ground cable.
2. Disconnect compressor clutch connector.
3. Purge the system of refrigerant.
4. Release the belt tension at the idler pulley and remove
the bit from the com pressor pulley. On some vehicles it
may be necessary to remove the crankshaft pulley in
order to remove the belt.
5. G Series— Remove the two bolts and two clamps that
hold the engine cover and remove the cover.
6. Remove the air cleaner to aid access to the compressor.
7. Remove fitting and muffler assem bly and cap or plug all
open connections.
8. Remove the nuts and bolts attach in g the compressor to
the bracket.
9. Remove the engine oil tube support bracket bolt and
nut from the compressor, and the com pressor clutch
ground lead.
Before beginning any com pressor disassem bly, drain
and m easure oil in the compressor. C heck for evidence of
contam ination to determ ine if rem ainder of system requires
servicing. C om pressor Servicing inform ation is located in
the Unit R epair M anual.
Installation
1. If the oil drain ed from the com pressor showed no
evidence of contam ination replace the sam e am ount of
fresh refrig eratio n oil into th e com pressor before
reinstallation. If it is necessary to service the entire
system because of excessive contam ination in the oil
removed, install a full charge of fresh refrigeration oil
in the compressor. (R efer to C hecking C om pressor Oil
C harge in the diagnosis section of this service m anual.)
2. Position com pressor on the m ounting b rack et and
install the nuts, bolts, lock washers, and ground wire.
3. Install the connector assem bly to the com pressor rear
head, using new " O "
refrigeration oil.
4. Connect the electrical lead to the coil and install and
adjust com pressor belt, using idler pulley. Refer to
"C om pressor Belt Tension A d ju stm e n t."
5. Evacuate, charge and check the system.
6. Replace air cleaner. On G series, replace the engine
cover.
7. Connect the battery ground cable.
because of excessive
rings coated w ith clean
ring coated w ith clean