Chevrolet 10 Series 1967, Service Manual

Page: 47 / 605

HEATER AND AIR CONDITIONING 1A-19
bulb will result in high low side pressures and poor
cooling. On bulbs located outside the evaporator case
insulation must be properly installed.
The external equalizer line shown in Figure 55 is not
used in the Custom and Chevy II All-Weather systems.
Indications of expansion valve trouble provided by the
Performance Test are as follows:
VALVE STUCK OPEN OR BROKEN POWER
ELEMENT
Noisy Compressor.
No Cooling - Freeze Up.
VALVE STUCK CLOSED OR PLUGGED SCREEN
Very Low Suction Pressure.
No Cooling.
POORLY LOCATED POWER ELEMENT BULB
Normal Pressure.
Poor Cooling.
ENGINE IDLE COMPENSATOR
This additional aid to prevent stalling during prolonged
hot weather periods is included with all air conditioned
vehicles. The idle compensator is a thermostatically
controlled air bleed which supplies additional air to the
idle mixture. On V
- 8
engines, with factory installed air
conditioning systems, the compensator is located within
the carburetor and is accessible when the engine air
cleaner is removed. On all other vehicles the compen­
sator is threaded into a manifold fitting below the car­
buretor. All compensators are factory set and are
non-adjustable. A malfunctioning unit should be replaced.
NOTE: If engine idle is erratic, hold the idle
compensator valve closed with a pencil or
wooden dowel while adjusting the idle mixture
screw(s). Never attempt to bend the bimetal
strip or attempt any valve adjustment.
f r
EXTERNAL
EQUALIZER LINE
F ig . 29 - Expansion V a lv e
EVACUATING AND CHARGING PROCEDURES
AIR CONDITIONING SYSTEM CAPACITY
Refrigerant
Charge Oil Charge
Four-Season System 3 lbs. 4 oz. 10 ozs. 525 viscosity
PURGING THE SYSTEM
In replacing any of the air conditioning components the
system must be completely purged or drained of r e ­
frigerant. The purpose is to lower the pressure inside
the system so that a component part can be safely
removed.
1. With engine stopped install high and low pressure
lines of gauge set to the proper high and low pres­
sure gauge fittings (see "Installing Gauge Set to
Check Operation").
2. With plug removed from the centerline on the gauge
manifold, open the vapor slowly through the center
connection.
CAUTION:
compressor
Do not open valves too much or
oil may be discharged with the
A rag wrapped around the end of
refrigerant.
the center gauge line will prevent the splashing
of oil in the event of accidental rapid discharge.
When the pressure is reduced to below 100 pounds
on the high pressure gauge, open the low pressure
gauge valve and continue discharging until all r e ­
frigerant has been released. Close both gauge valves.
EVACUATING AND CHARGING THE SYSTEM
GENERAL NOTE: In all evacuating procedures
shown below, the specification of 26-28 inches
of Mercury vacuum is used. These figures are
only attainable at or near Sea Level Elevation.
For each 1000 feet above sea level where this
operation is being performed, the specifications
should be lowered by 1 inch. Example: at 5000
ft. elevation, only 21 to 23 inches of vacuum can
normally be obtained.
Whenever the air conditioning system is open for any
reason, it should not be put into operation again until it
has been evacuated to remove air and moisture which
may have entered the system.
The following procedures are based on the use of the
J-8393 Charging Station.
Filling Charging Cylinder
1. Open control valve on refrigerant drum.
2. Open valve on bottom of charging cylinder allowing
refrigerant to enter cylinder.
3. Bleed cylinder valve on top (behind control panel) as
required to allow refrigerant to enter. When re ­
frigerant reaches desired level (see "Air Condition­
ing System Capacities"), close valve at bottom of
CHEVROLET TRUCK SERVICE MANUAL