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6-5
T -309
6.7 R EFRIGERANT CHARGE
6.7.1 Checking the Refrigerant Charge
NOTE
To avoid damage to the earth’s ozone layer, use
a refrigerant recovery system whenever remov-
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-
chargeandsuction service valves.For units operating
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). Thenset thecontrol-
ler set point to --25_C(--13_F) to ensure that the suc-
tion modulation valve is fully open. (Position of the
suction modulating valve may be checked at control-
ler function code Cd01.)
c. Partially block the condenser coil inlet air. Increase
the area blocked until the compressor discharge pres-
sure is raised to approximately 12 kg/cm@ (175 psig).
d. On units equipped with a receiver, the level should be
between the glasses. On units equipped with a water
cooled condenser, the level should be at the center of
the glass. If the refrigerant level is not correct, contin-
ue with the following paragraphs to addor removere-
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. Place cylinder of R-134a on scale and connect charg-
ing line from cylinder to liquid line valve. Purge
charging line at liquid line valve andthen note weight
of cylinder and refrigerant.
c. Open liquid valve on cylinder. Open liquid line valve
half-way and allow the liquid refrigerant to flow into
the unit until the correct weight ofrefrigerant (refer to
paragraph
2.2) has been added as indicated by 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. Backseat manual liquid line valve (to close off gauge
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. Examine the unit refrigerant system for any 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-
vice valve and slowly add charge until the refrigerant
appears at the properlevel . Be careful not to frontseat
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 p ressure very
carefully by slightly loosening the couplings
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 compr essor in a deep
vacuum.
6.8.1 Removal and Replacement of Compressor
NOTE
Service compressor contains a nitrogen charge.
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. Procure a replacement compressor kit. A list of items
contained in the compressor kit is provided in
Table 6-1.
b. If the compressor is operational, pump the unit down
(refer to paragraph 6.4).