Carrier 69NT40-561-201, Руководство по эксплуатации и обслуживанию, Страница: 85 / 117

6 − 4 T-364
c. Test the evacuation setup for leaks by backseating
the unit service valves and drawing a deep vacuum
with the vacuum pump and gauge valves open. Shut
off the pump and check to see if the vacuum holds.
Repair leaks if necessary.
d. Midseat the refrigerant system service valves.
e. Open the vacuum pump and electronic vacuum
gauge valves, if they are not already open. Start the
vacuum pump. Evacuate unit until the electronic vac-
uum gauge indicates 2000 microns. Close the elec-
tronic vacuum gauge and vacuum pump valves. Shut
off the vacuum pump. Wait a few minutes to be sure
the vacuum holds.
f. Break the vacuum with either clean dry refrigerant 134a
or dry nitrogen. Raise system pressure to roughly 0.14
bar (2 psig), monitoring it with the compound gauge.
g. If R134a was used, remove refrigerant using a refrig-
erant recovery system. If nitrogen was used, relieve
the pressure.
h. Repeat steps e. and f. one time.
i. Remove the copper tubing and change the filter drier.
Evacuate unit to 500 microns. Close the electronic
vacuum gauge and vacuum pump valves. Shut off the
vacuum pump. Wait five minutes to see if vacuum
holds. This procedure checks for residual moisture
and/or leaks.
j. With a vacuum still in the unit, the refrigerant charge
may be drawn into the system from a refrigerant con-
tainer on weight scales.
6.6.4 Partial System
a. If refrigerant charge has been removed from the low
side only, evacuate the low side by connecting the
evacuation set-up at the compressor suction valve
and the liquid service valve but leave the service
valves frontseated until evacuation is completed.
b. Once evacuation has been completed and the pump
has been isolated, fully backseat the service valves to
isolate the service connections and then continue
with checking and, if required, adding refrigerant in
accordance with normal procedures.
6.7 REFRIGERANT CHARGE
WARNING
EXPLOSION HAZARD Failure to follow this
WARNING can result in death, serious
personal injury and / or property damage.
Never use air or gases containing oxygen
(O2) for leak testing or operating the
product.
Charge only with R
− 134a: Refrigerant must
conform to AHRI Standard 700
specification.
6.7.1 Checking the Refrigerant Charge
NOTE
Use a refrigerant recovery system whenever
removing refrigerant. When working with refrig-
erants 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-
charge and suction service valves.
b. Bring the container temperature to approximately
0 C (32 F) or below. Then set the controller set point
to -25 C (-13 F).
c. Partially block the condenser coil inlet air. If covering the
lower portion of the coil is not sufficient, remove the left
hand infill panel and cover the left side of the coil. In-
crease the area blocked until the compressor discharge
pressure is raised to approximately 12.8 bar (185 psig).
d. The refrigerant level should be between the glasses
on the receiver. If the refrigerant level is not correct,
continue with the following paragraphs to add or re-
move refrigerant as required.
6.7.2 Adding Refrigerant to System (Full Charge)
a. Evacuate unit and leave in deep vacuum. (Refer to
paragraph 6.6.1.)
b. Place cylinder of R-134a on scale and connect charg-
ing line from cylinder to liquid line valve. Purge charg-
ing line at liquid line valve and then note weight of cyl-
inder 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 of refrigerant (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.
d. Backseat manual liquid line valve (to close off gauge
port). Close liquid valve on cylinder.
e. Start unit in cooling mode. Run for 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 service
valve and slowly add charge until the refrigerant
appears at the proper level. Be careful not to frontseat
the suction valve fully, if the compressor is operated in
a vacuum, internal damage may result.