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full out
(counter clockwise)
the
gauge adaptor fitting is closed, allow-
ing the cap to be removed and line to
be
attached.
Turning the stem (clock-
wise) opens the gauge
port.
To shut
the valve off to or from the compres-
sor,
the stems must be full in (clock
wise)
.
On compressors equipped with Dill
core valve
ports,
the compressor can
be shut-off from the system by clamp-
ing off the suction and discharge
hoses.
The compressor mounts horizon-
tally to the left (8 cyl.) and 250 2V
to right. 250 1 V compressor is
mounted vertically on the right.
(d) MAGNETIC CLUTCH
Fig.
24
The compressor drive clutch allows
the system to
be
"on" or "off" as
desired and also provides positive
temperature control when combined
with a thermostatic
switch.
The basic
parts of the clutch are the field drive
assembly.
(F
ield
coil,
bearing,
slip
ring
and
pulley),
clutch plate
as-
sembly and brush bracket
assembly.
The magnetic clutch is employed
also to allow the compressor pulley to
free wheel when the air conditioner
is not being used,
therefore,
the com-
pressor is not operating needlessly.
Therefore, during the winter or off
season it is not necessary to remove
the belt from the compressor
pulley.
PART 16-2- AIR CONDITIONING
The compressor clutch has a ball-
bearing which is pressed into the field
coil assembly and located with a snap
ring. The clutch plate assembly is
pressed into the bearing and held by a
snap ring, and the hub is then secured
to the tapered compressor shaft with
a locking bolt. This permits the clutch
pulley to free wheel when the field
coil is not
energised.
When the evaporator air and tem-
perature switches are turned
on,
cur-
rent is allowed to flow to the field
coil energising the
electro-magnet;
this causes the clutch plate to be held
in contact with the field coil and
compressor
pulley,
thus the
compres-
·sor is being driven through the clutch
plate.
In the off position of the evap-
orator air switch the electro-magnet
is not energised and the clutch plate
does not contact the field coil
as-
sembly and therefore does not drive
the
compressor.
(e) CONDENSOR
Like the evaporator, the condensor
is of fin and tube construction.
Discharge gas from the compressor
is pumped to the
condensor,
mounted
ahead of the car
radiator.
Air passing
over the condensor first removes the
heat of compression from the gas,
then condenses it to a liquid
state.
Temperature of the air through the
EJ
DIAGNOSIS AND TESTING
GAUGES INDICATE LOW HEAD
PRESSURE:
1. Defective compressor valves.
Replace valve plate.
2. Blown or defective gasket.
Replace
gaskets.
GAUGES INDICATE LOW
SUCTION PRESSURE:
1.
Insufficient
refrigerant.
If bubbles or frothing are appar-
ent in sight glass, add freon until
condition is
corrected.
2.
Restriction at drier or in lines
usually indicated by frosting at
point of restriction or lines being
cool on side of restriction away
from
compressor.
Replace faulty part or remove re-
striction.
3. Expansion valve faulty
.
6.
Moisture freezing in expansion
valve.
Expansion valve and manifolding
will be frosted while coil tubes will
show little or no frost. Install new
drier, evacuate system and re-
charge.
7.
Sticking of expansion valve caused
by corrosion.
8. Clogged drier indicated by frost
forming on drier.
9.
Low air supply to evaporator.
GAUGES INDICATE HIGH
SUCTION PRESSURE:
1.
Expansion
valve
faulty
.
2.
Leaking or broken compressor
valves.
Repair or replace valves with valve
kit.
3. Compressor drive belt
slipping.
Adjust for proper
tension.
4. Magnetic clutch
slipping.
Check electrical circuit for proper
voltage to
clutch.
5.
Expansion valve not
closing.
Evaporator coil flooding, causing
suction line to frost.
6. Suction service
valve strainer
clogged.
Remove, clean and replace.
OVERHEATING OF ENGINE:
1. Loose Fan Belt.
2.
Collapsing or obstructed radiator
16-9
condensor must be lower than the
saturation temperature of the dis-
charge
gas.
Air temperature and
quantity determine the condensing
temperature and
pressure.
The top fitting of the condensor is
to be used as the inlet fitting from the
compressor. The lower fitting is for
the liquid line returning freon to the
receiver.
Servicing the condensor coil con-
sists mainly of removing bugs, dirt
and other foreign matter would tend
to restrict airflow across the con-
densor.
(f)
RECEIVER-DRIER-SIGHT
GLASS
The receiver is a cylindrical hous-
ing incorporating inlet and outlet
ports filters, drier and
sight-glass.
It functions as a reservoir for the
liquid refrigerant from the conden-
sor providing sufficient charge for all
variations of weather. The drier
serves as a moisture trap and filters
minute substances which may travel
through the refrigerant
circuit.
The
sight
glass
aids
in
determining
whether system is fully charged or
not. In fully charged systems the
sight glass will appear clear and
when undercharged it will continue
bubbling or frothing when the system
is
operated.
hoses.
3. Faulty pressure cap on
radiator.
4. Radiator plugged or exceedingly
dirty.
5. Inoperative thermostat-
replace.
6. Bugs or dirt clogging fins of con-
denser or radiator- clean off.
7. Excess freon charge- purge
over-
charge.
COMPRESSOR DRIVE BELT
TROUBLES:
1. Tension of drive belt -
tension
new belts at 100-140 lbs. and belts
that are worn in at 90-110
lbs.
2.
Drive belt slipping but correctly
tensioned.
Caused by overcharge of refriger-
ant,
obstruction to cooling by con-
denser or air in system resulting
in high head
pressures.
3.
Belt life affected by incorrect pul-
ley alignment, broken or buckled
pulleys, or excessive oil on belt or
fracture of cords due to forcing
belt in place.
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