Chevrolet 70 1969 Series, Shop Manual

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C A B A N D BO DY M O U N T IN G S 1-67
T E S T R E A D I N G S
Ambient Air in Degrees F. (In Auxiliary
Fan Air Blast 2" Ahead of Condenser).
70 80 90 100 110
Air Quality Arid Humid Arid Humid Arid Humid Arid Humid Arid Humid
Average Compressor Head
P re ssu re -P S 1 125/155 150/180 160/190 180/210 197/227 213/243 225/255 250/280 270/300 290/320
Average Suction Throttling Valve
Pressure—PSI
20/23 21/24 20/23 22/25 21/24 25/28 24/27
29/32
28/31 36/39
Center Outlet Temperature Degree F. 41/44 48/52
44/48 53/57
48/52 58/62 52/57 62/68 58/65 68/75
Shown in the above table are the average readings expected in arid or dry air, and in humid or moist air with maximum allowable tolerance
shown.
Humid air is considered 2 0 -9 0 % R.H. Nozzle
Arid air is considered 5—20% R.H. Nozzle
Figure 11 — Operational Test Data Chart
provide an internal pressure at slightly above
atmospheric pressure.
A SSEM B LY
1. All precautions should be taken to prevent
damage to fittings or connections. Even minute
damage to a connection could cause it to leak.
2. Any fittings getting grease or dirt on them
should be wiped clean with a cloth dampened with
alcohol. Do not use chlorinated solvents such as
trichloroethylene for a cleaning agent, as they are
contaminants. If dirt, grease or moisture gets in­
side the hoses and cannot be removed, the hose
should be replaced.
3. Sealing caps should be removed from sub-
assemblies just prior to making connections for
final assembly.
4. Use a small amount of clean refrigeration
oil (525 or 1000 viscosity) on all tube and hose
joints, and dip the O-ring gasket (when used) in
this oil before assembling the joint, as this oil will
help in making a leak-proof joint.
5. Do not connect the receiver-dehydrator as­
sembly until all other sealed sub-assemblies have
been connected. This is necessary to insure opti­
m um dehydration and maximum moisture protec­
tion of the refrigeration system.
C A U T IO N - LIQUID IN D IC A T O R (SIGHT GLASS)
Under normal conditions, the receiver-dehy­
drator will show clear with about 3 pounds of re­
frigerant in the system. However, the air condi­
tioner will not produce its best performance until
3-1/4 pounds of refrigerant are in the system. Do
not overcharge with refrigerant, as this will result
in extremely high head pressures and the com ­
pressor safety valve will "blow."
PERFORMANCE TESTING
In order to determine if an air conditioning
system is operating properly and efficiently, it must
be performance tested. The first step to diagnosing
a system that has been malfunctioning should be a
complete performance test (see fig. 11).
Correct pressures indicate that the required
charge of refrigerant is in the system and that it
is functioning properly.
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L