Container Refrigeration Operation & Service

6-5
T -309
6.7 REFRIGERANT CHARGE
6.7.1 Checking the Refrigerant Charge
NOTE
Toavoiddamagetothe earth’sozonelayer, use
arefrigerant recoverysystemwheneverremov-
ing refrigerant. When working with refriger-
ants you must comply with all local govern-
ment environmental laws. In the U.S. A., refer
to EPA section 608.
a. Connect the gauge manifold to the compressor dis-
chargeandsuctionservicevalves.Forunitsoperating
on a water cooled condenser, change over to air
cooled operation.
b. Bring the container temperature to approximately
1.7_C(35_F)or--17.8_C(0_F).Thensetthecontrol-
lerset point to --25_C(--13_F)to ensurethat thesuc-
tion modulation valve is fully open. (Position of the
suctionmodulatingvalvemaybecheckedatcontrol-
ler function code Cd01.)
c. Partially block the condenser coil inlet air. Increase
theareablockeduntilthecompressordischargepres-
sureisraisedtoapproximately12kg/cm@(175psig).
d. Onunitsequippedwithareceiver,thelevelshouldbe
between the glasses. On units equipped with a water
cooledcondenser, the level should be at the centerof
theglass.Iftherefrigerantlevelisnotcorrect,contin-
uewiththefollowingparagraphstoaddorremovere-
frigerant as required.
6.7.2 Adding Refrigerant to System (Full Charge)
a. Evacuate unit and leave in deep vacuum. (Refer to
paragraph 6.6.)
b. PlacecylinderofR-134aonscaleandconnectcharg-
ing line from cylinder to liquid line valve. Purge
charginglineatliquidlinevalveandthennoteweight
of cylinder and refrigerant.
c. Openliquidvalveoncylinder.Openliquid linevalve
half-wayand allow theliquid refrigerantto flowinto
theunituntilthecorrectweightofrefrigerant(refert o
paragraph
2.2) hasbeenaddedas indicatedby scales.
NOTE
It may be necessary to finish charging unit
through suction service valve in gas form, due
to pressure rise in high side of the system.
(Refer to section paragraph 6.7.3)
d. Backseatmanualliquidlinevalve(toclose offgauge
port). C lose liquid valve on cylinder.
e. Start unit in cooling mode. Run approximately 10
minutes and check the refrigerant charge.
6.7.3 Adding Refrigerant to System (Partial
Charge)
a. Examinethe unit refrigerant system forany evidence
of leaks. Repair as necessary. (Refer to paragraph
6.5.)
b. Maintain the conditions outlined in paragraph 6. 7.1
c. Fully backseat the suction service valve and remove
the service port cap.
d. Connect charging line between suction service valve
port and cylinder of refrigerant R-134a. Open
VAPOR valve.
e. Partially frontseat (turn clockwise) the suction ser-
vicevalveandslowlyaddchargeuntiltherefrigerant
appearsattheproperlevel.Becarefulnottofrontseat
the suction valve fully, if the compressor is operated
in a vacuum internal damage may result.
6.8 COMPRESSOR -- Model RSH105
WARNING
Make sure power to the unit is OFF and
power plug disconnected before replacing
the compressor.
WARNING
Before disassembly of the compressor make
sure to relieve the internal pressure very
carefullyby slightlyloosening thecouplings
to break the seal.
CAUTION
The scroll compressor achieves low suction
pressure very quickly. Do not use the com-
pressor to evacuate the system below zero
psig. Never operate the compr essor with the
suction or discharge service valves closed
(fr ontseated). Internal damage will result
fr om operating the compressor in a deep
vacuum.
6.8.1 Removal and Replacement of Compressor
NOTE
Servicecompressorcontainsanitrogencharge.
Due to the hygroscopic nature of the oil, time
the compressor is left open to the atmosphere
should be minimized as much as possible.
a. Procureareplacementcompressor kit. Alist ofitems
contained in the compressor kit is provided in
Table 6-1.
b. Ifthecompressorisoperational, pump the unit down
(refer to paragraph 6.4).