Chevrolet 1980 Light Duty Truck Service Manual page 68

1B-22 AIR CO N D ITIO N IN G
REAR BLOWER
RESISTOR
c ! St <
— 2 LT BLUfcLK-872
— 2 Y E L/ LK-851—
b
— 2 ORN/ LK-852—
b
(WQ-C60-
W K
SPECIFIC C O M P O N E N T DIAG NOSIS
The following is a description of the type of symptom
each refrigerant component will evidence if a defect occurs:
COMPRESSOR
A compressor defect will appear in one of four ways:
Noise, seizure, leakage, or low discharge pressure.
NOTICE: Resonant compressor noises are not cause
for alarm; however, irregular noise or rattles may
indicate broken parts or excessive clearances due to
wear. To check seizure, de-energize the magnetic
clutch and check to see if drive plate can be rotated.
If rotation is impossible, compressor is seized (See
"False Compressor Seizure"). To check for a leak, refer
to leak testing. Low discharge pressure may be due to
a faulty internal seal of the compressor, or a restriction
in the compressor.
Low discharge pressure may also be due to an
insufficient refrigerant charge or a restriction elsewhere
in the system. These possibilities should be checked
prior to servicing the compressor. If the compressor is
inoperative, but is not seized, check to see if current
is being supplied to the magnetic clutch coil terminals.
-12004752 GROM MET
•917542-
- 2 LT BLl/BLK-872 —
I t r i l - r r i
-2LTBLIVBLK-
H4I I M I - 2 YEL/BLK-851 —
- 2 YEL/B LK -
|.»i - 2 ORNfcLK-852A
\ . V r i
-2 ORfVBLK-
I.M H.l
-30RfVB LK-852B
- 2 BR N-50
ill
-2 B R N -50
r— 3 BRlVW HT-850
I 2004893
FUSE BLOCK
Fig. 1B-17—Overhead Systems Wiring Diagrams-AII
REAR A/C SWITCH
8917583- -8917 580 W
> — 30«N feLK -852B - 5 O RfVBLK-852— 1
8917583-
-2 B R N -5 0 -
2BRN INST PNLHARN.
FUSED 25AMP
CONDENSER
A condenser may be defective in two ways: it may leak,
or it may be restricted. A condenser restriction will result
in excessive compressor discharge pressure. If a partial
restriction is present, sometimes ice or frost will form
immediately after the restriction as the refrigerant expands
after passing through the restriction. If air flow through the
condenser or radiator is blocked, high discharge pressures
will result. During normal condenser operation, the outlet
pipe will be slightly cooler than the inlet pipe.
RECEIVER-DEHYDRATOR - M O TO R HOM E
CHASSIS
A defective receiver-dehydrator may be due to a
restriction inside the body of the unit. A restriction at the
inlet to the receiver-dehydrator will cause high head
pressures. Outlet tube restrictions will be indicated by low
head pressures and little or no cooling. An excessively cold
receiver-dehydrator outlet may be indicative of a restriction.
EXPANSIO N VALVE
A malfunction of the expansion valve will be caused
by one of the following conditions: valve stuck open, valve
stuck closed, broken power element, a restricted screen or
an improperly located or installed power element bult. The
first three conditions require valve replacement. The last
two may be corrected by replacing the valve inlet screen and
by properly installing the power element bulb.
J B
-b
f n
U J
REAR BLOWER
MOTOR
SHEET
METAL
GRD
LIG H T T R U CK S E R V IC E M AN UAL