Chevrolet 1977 light duty truck Service Manual page 77

Overhead System (G Models)
(R efrigerant Charge — 5 lbs.-4 o z.)
T em p eratu re o f
Air E ntering 70° 80°
C ondenser
Engine rpm
C om pressor
5 0 - 1 6 0 -
Head Pressure*
2 00 210
S uction
13 1 3-
Pressure* 19 21
D ischarge A ir
3 8 3 8 -
T em p, at R ight
44 44
F ro n t U pper
R ear systejn tem p era tu res a t cen ter o u tle t
O u tlet*
ru n 5 - 1 0
N O T E: The oil may
considered normal.
To further check the compressor oil charge, should
the above test show insufficient oil, it is necessary to
remove the compressor from the vehicle, drain and
m easure the oil as outlined under "C hecking Compressor
Oil C h arg e."
C hecking Com pressor Oil Charge
1. Run the system for
engine rpm with controls set for m axim um cooling and
high blower speed.
2. T urn off engine, discharge the system, remove
compressor from vehicle, place it in a horizontal position
with the drain plug downward. Remove the drain plug
and, tipping the compressor back and forth and rotating
the compressor shaft, d rain the oil into a clean container,
m easure and discard the oil.
3. Add new refrigeration oil to the compressor as
follows.
a. If the quantity drained was 4 fluid oz. or
more, add the same am ou nt of new refrigeration oil to
the replacem ent compressor.
b. If the quantity drained was less than 4 fluid
oz., add 6 fluid oz. of new refrigeration oil to the
replacem ent compressor.
c. If a new service compressor is being installed,
drain all oil from it an d replace only the am ount
specified in Steps 3a and 3b above.
d. If a field repaired
installed, add one additional fluid oz. to the compressor.
90° 100° 110° 120°
2000
2 0 0 - 2 2 5 - 2 5 0 - 2 8 0 -
250 275 300 320
1 6 - 1 9 - 23 2 6 -
24 27 31 34
3 9 - 4 5 - 5 0 - 54 -
47 53 58 62
higher th an fro n t system .
app e a r foamy. This
10 minutes at 500-600
compressor is being
Dash M ounted U n it (M o to r Hom e Chassis)
(R efrig eran t Charge — 3 lb s.-4 oz.)
T em p eratu re o f
Air E nterin g
70°
C ondenser
Engine rpm
C om pressor
1 1 0 -
Head Pressure* 120
S u ctio n
Pressure psi*
D ischarge A ir
4 0-
T em p eratu re* 45
* Ju st p rio r to com pressor clu tch disengagem ent.
is 4. In the event that it is not possible to idle the
compressor as outlined in Step 1 to effect oil return to it,
proceed as follows:
a. Remove the compressor, drain, measure and
discard the oil.
b. If the am ount drained is more than 1-1/2
fluid oz. and the system shows no signs of a m ajor leak,
add the same am ount to the replacement compressor.
c. If the am ount drained is less than 1-1/2 fluid
oz. and the system appears to have lost an excessive
am ount o f oil, add 6 fluid oz. of clean refrigeration oil to
replacement compressor,
compressor.
If the oil
material, replace the receiver-dehydrator (expan­
sion tube on C-K models) and flush or replace all
com ponent parts as necessary. A dd
specified volume o f new refrigeraton oil to the
replacement compressor.
5. Add additional oil in the following amounts for
any system components being replaced.
Evaporator C o r e ................................... 3 fluid oz.
C o n d e n s e r.... :......................................... 1 fluid oz.
R eceiv er-D eh y d rato r........................... 1 fluid oz.
A ccu m u la to r........................................... 1 fluid oz.
When adding oil to the compressor,
C A U TIO N :
it will be necessary to tilt the rear end o f the
compressor up so that the oil will not run out o f
the suction and discharge prots. Do not set the
compressor on the shaft end.
80° 90° 100° 110°
2000
13 5 - 1 60- 19 0 - 220-
145 170 200 230
6 7 9 10 10
41 - 4 1 -
4 2 - 44-
46 46 47 49
7 fluid oz. to a
contains chips or other
120°
260-
270
13
4 4-
49
repaired
foreign
the full