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Crusader
MC-8
MAINTENANCE
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MANUAL
AIR IN SYSTEM
If
air or non-condensible gases are present, they
usually move toward the receiver. The discharge
pressure will rise above the pressure corresponding
to the condensing temperature. To check this the
system must be allowed to stand idle for several
hours to cool down to the temperature of the
surrounding air. Check the temperature at the con-
denser and receiver. Check the pressure at the com-
pressor discharge. This pressure should be within 3
psi. of the saturation pressure corresponding with the
surrounding temperature.
EVACUATING SYSTEM
I.
Dump charge by opening the purge cock on the
receiver tank. Close the cock.
2.
Open both receiver valves by turning "out".
3.
Place the two compressor valves, suction and
discharge, in a neutral position by turning each
one six turns "in" from the "out" position.
4.
Remove the caps from the two 90° adapters on
the suction and discharge valves and connect two
hoses to the vacuum hose.
5.
Start the vacuum pump. Open the large shut-off
valve and close the small vacuum gauge valve.
6.
The pressure will drop to approximately 29"
vacuum fairly quickly. The dial gauge only gives
a general idea on the absolute system pressure.
Open the smaller valve to read the Jas. P. Marsh
vacuum gauge. It will be necessary to leave it open
several minutes to get a true reading.
Do not
leave it open except when checking the
pressure otherwise the water in the gauge will boil
off.
CAUTION: Before evacuating, make sure there is
water in the gauge.
If
low, add distilled water.
A plugged dehydrator is indicated by differences in
temperatures on either side of the dehydrator.
7.
Normally, it will take about an hour for the
pressure to come down to a point where the
thermometer reads 32°F. A damp system will
take longer. Evacuation must be taken down to at
least 32°. Note that water in the gauge will freeze
below 32°. Any readings below this will not be
accurate.
8.
Backseat the compressor valves by turning "out"
all the way.
9.
Shut down the vacuum pump.
I 0. Remove the hoses.
I I. Reinstall the caps at the suction valve take-off
points.
CHARGING SYSTEM
When a system has been opened or if there is any
question about the air or moisture in the system,
EVACUATE the system. Charging of an evacuated
system may be accomplished by forcing liquid Freon
12 or Freon 500 directly into the receiver tank.
This
may
be
accomplished
by
placing
the
refrigerant tank upside down on a s~ale_ (bathr~om
type) with valving at the ?Ottom and liquid charg1_ng.
This ensures that only liquid enters the reservoir.
l.
Backseat the two compressor shut-off valves
("out").
2.
Install the test gauges at the shut-off valves
noting that the 400 psi. gauge is connected to the
discharge.
3.
Turn in the two shut-off valves 3 to 4 turns.
4.
Open the lower receiver valve by turning all the
way "out".
5.
Backseat the upper receiver valve by turning all
the way "out".
6.
Remove the cover cap from the service fitting in
the top receiver valve.
7.
Attach a charging hose to the Freon tank. Open
the tank valve slightly permitting Freon to escape
thus purging the hose of air.
8.
Connect the charging hose
to
the service fitting.
9.
Open the Freon tank valve.
IO. Turn in the upper receiver valve several turns.
The Freon will now enter the system.
I I. The proper charge of Freon is 21 pounds. When
the
scale
indicates
this
amount
of charge,
backseat the receiver valve and close the Freon
tank valve.
12. Disconnect the charging hose. Replace the cover
caps.
13. The system is now ready for operation.
LUBRICATION
Too much oil in the system is just as harmful as
too little. To ensure proper lubrication, the level
should be maintained within certain limits.
When operating at normal loads, the l_evel at the
glass in the compressor should be approximately I /2
full. After standing, it may show 2/3 full. Some
variation to these levels is permissible, particularly
when operating.
After standing idle for any length of time, t_he com-
pressor will normally pump crankcase 011 into _the
system and approximately 20 minutes of running time
may be required to bring it back to the crankcase.
After the unit has run at least one-half hour, the
crankcase temperature should be warm to touch.
If
cool, this indicates the expansion valv~ ad-
justment is passing too much liquid or there
1s
_ex-
cessive oil in the system. Oil level is always lower in a
cool crankcase due to cooling evaporating refrigerant
causing oil to foam and be carried out into the
system.
ADDING OIL
1) Check supply of refrigerant in system. Lack. of
refrigerant will cause the glass to show in-
sufficient oil.
2)
Pump the system down and reduce compressor
pressure to approximately 2 psi. Stop the com-
pressor.
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