Carrier X4 7300 Operation & Service Manual page 241

11. Open the vacuum pump valve and start the
pump. Evacuate unit to 500 microns. Close the
vacuum pump valve and shut off the pump. Wait
a few minutes to be sure the vacuum holds
below 2000 microns.
12. If vacuum holds below 2000 microns continue to
step 14. If vacuum rises above 2000 microns
continue to step 13.
13. Repeat steps 8 through 11 until the vacuum
stays below 2000 microns.
14. Once the system holds a good vacuum, it is
ready to be charged with refrigerant. Refer to
Section 8.7.2.
b. Evacuation of the Low Side
1. Evacuate only after a low side leak check.
(Refer to Section
2. If possible keep the temperature of the major
components (condenser, evaporator, compres-
sor and receiver) above 60°F (15.6°C) to speed
evaporation of moisture. If the temperature is
lower than 60°F (15.6°C), ice might form before
moisture removal is complete. Heat lamps, heat
guns or alternate sources of heat may be used
to raise system temperature.
3. The recommended method to evacuate the sys-
tem is to connect three evacuation hoses with
vacuum pump and vacuum indicator (see
ure 8.22).
4. Ensure that the operator message panel dis-
plays "RECOVER/LEAK CHK/EVAC MODE"
during the evacuation and dehydration proce-
dures. (Refer to Section
system switches to Charge Mode during the
process, switch it back to the "RECOVER/LEAK
CHK/EVAC MODE".
5. Leave the liquid line service valve and the dis-
charge service valve frontseated and then mid-
seat the suction service valve.
6. Start the vacuum pump. Evacuate unit until the
electronic vacuum gauge indicates 2000
microns. Close the vacuum pump valve and
shut off the pump. Wait a few minutes to be sure
the vacuum holds.
7. Break the vacuum with dry nitrogen through the
liquid line service valve. Raise system pressure
to approximately 2 psig (0.1 bar). Ensure that
the control system does not switch to the
8.7.3)
5.2.5.) If the control
Charge Mode. If this occurs, switch it back to the
"RECOVER/LEAK CHK/EVAC MODE" (Refer to
Section 5.2.5.
8. Purge nitrogen from the low side of the system
at the suction service valve.
9. Open the vacuum pump valve and start the
pump. Evacuate unit to 500 microns. Close the
vacuum pump valve and shut off the pump. Wait
a few minutes to be sure the vacuum holds
below 2000 microns.
10. If vacuum holds below 2000 microns continue to
step 12. If vacuum rises above 2000 microns
continue to step 11.
11. Repeat steps 6 through 9 until the vacuum stays
below 2000 microns.
12. Once the system holds a good vacuum, open
the compressor discharge service valve and the
liquid line service valve.
13. Start unit and check the refrigerant charge.
Refer to Section
c. Evacuation of the Compressor
1. Evacuate only after a compressor leak check.
Refer to Section
2. Ensure the unit will not start automatically by dis-
abling any two way communication and placing
Fig-
the STOP/RUN-OFF switch in the OFF position.
3. If possible keep the temperature of the com-
pressor above 60°F (15.6°C) to speed evapora-
tion of moisture. If the temperature is lower than
60°F (15.6°C), ice might form before moisture
removal is complete. Heat lamps, heat guns or
alternate sources of heat may be used to raise
compressor temperature.
4. Connect evacuation equipment to the compres-
sor suction and discharge service valves. See
Figure 8.22.
5. Start the vacuum pump. Evacuate compressor
to 500 microns. Close the vacuum pump valve
and shut off the pump. Wait a few minutes to be
sure the vacuum holds. This checks for residual
moisture and/or leaks.
6. Once the compressor holds a good vacuum,
open the compressor suction and discharge ser-
vice valve to allow refrigerant to enter the com-
pressor.
7. Start unit and check the refrigerant charge.
Refer to Section
8–27
8.7.2.
8.7.3.
8.7.2.
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