Chevrolet Light Duty Truck 1973 Service Manual page 83

replaced it may be necessary to remove and
replace the throttle cable during the belt
replacement. If so check throttle cable
adjustment upon completion. It may also be
necessary to remove the crankshaft pulley to
install a new compressor belt.
COMPRESSOR FAILURE
If the compressor has failed mechanically to the extent
that metal chips and shavings are found in it, the system
should be checked for foreign material and cleaned as
described under Foreign M aterial in the System.
FALSE COMPRESSOR SEIZURE
Slipping or broken air conditioning drive belts and/or
scored clutch surfaces may be experienced on initial start
up of an air conditioning compressor after an extended
period of storage or non-operation of the compressor.
This would indicate a seized compressor; however, an
overhaul or replacement of the compressor may not be
necessary.
During extended periods of non-operation, changes in
temperature cause the refrigerant in the air conditioning
compressor to expand and contract. During this
movement, lubricating oil carried by the refrigerant
tends to migrate from highly polished surfaces in the
compressor such as the ball seats and wobble plate.
W ithout lubricating oil at these polished surfaces, they
"w ring" together and appear to be seized.
Before the time and expense of an overhaul is invested,
use the following check to determine if the compressor is
actually seized. With a wrench on the compressor shaft
lock nut or Spanner Wrench J-9403 on ihe clutch drive
plate, "rock" the shaft in the opposite direction of
normal rotation. After the compressor is broken loose,
"rock" the shaft back and forth. This should be sufficient
to return lubricating oil to the "wrung" surfaces and
allow the compressor shaft to be turned by hand. Once
the compressor turns freely, rotate the compressor at
least three complete turns. Start the engine and operate
the compressor for a minimum of one minute.
This procedure will not affect a compressor that is
actually seized but should be attem pted before
overhauling a compressor known to be idle for a month
or longer.
COLLISION PROCEDURE-ALL SYSTEMS
Whenever a vehicle equipped with an air conditioning
unit is involved in a collision or wreck, it should be
inspected as soon as possible. The extent of damage to
any or all of the component parts and the length of time
the system has been exposed to the atmosphere will
determine the replacement of parts and processing that
will be required. The greater the length of time of
exposure to the atmosphere, the greater will have been
the chances for air, moisture and dirt to have entered
and damaged the system. Every case may be entirely
HEATER AND AIR C O N D IT IO N IN G
different so it is not possible to establish a hard and fast
procedure to follow each time. Good judgment must be
used to determine what steps should be taken in each
specific case.
The following procedure is presented as a guide for use
when inspecting a damaged vehicle equipped with air
conditioning.
1. Remove the drive belt.
2. Visually inspect the condenser, accumulator,
receiver-dehydrator, compressor, mounting brack­
ets, conditioning unit, all connecting lines, and all
controls to determine the extent and nature of the
damage.
a. No repairs, such as soldering, welding or
brazing, should be attempted on the condenser
because of its construction. If the vapor passages
in the horizontal tubes or return bends or
manifolds have been damaged in any way, the
condenser should be replaced with a new one.
b. The accumulator or receiver-dehydrator should
be replaced if there is any evidence of its
having sustained either internal damage or a
fracture at any of the lines or welded joints or if
the system has been exposed to the atmosphere
for an undetermined period of time.
c. Examine the compressor for any visible external
damage.
d. The evaporator should be examined for damage
and, if necessary, removed or replaced or the
entire unit processed where damaged or exposed
to the atmosphere.
e. All connecting lines and flexible hoses should be
examined throughout their entire length for
damage. If damaged in any manner, replace
with new lines.
f. Check all controls and connecting wires for
damage and replace with new parts where
needed.
g. Check the clutch pulley for proper operation
and freedom from damage.
3. Install Charging Station.
4. Purge the system.
5. Remove the compressor from mounting and
remove the oil test fitting.
6. Pour out the oil into a clean glass container and
examine it for any foreign substance such as dirt,
water, metal particles, etc. If any of these are
present, the compressor, expansion tube, and
accumulator or receiver-dehydrator should be
replaced and the other system components should
be flushed with liquid refrigerant.
7. If the oil is clean and free of any harmful
substance, replace oil with Frigidaire 525 Viscosity
Oil, or equivalent.
NOTE: If the system components have been
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LIGHT DUTY TRUCK SERVICE MANUAL