System Evacuation And Charging; Using Vacuum Pump; Deep Vacuum Method; Triple Evacuation Method - Midea DLCERAA12AAJ Service Manual

SYSTEM EVACUATION AND
CHARGING
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Never use the system compressor as a vacuum pump.
Refrigerant tubes and indoor coil should be evacuated using the
recommended deep vacuum method of 500 microns. Always break a
vacuum with dry nitrogen.
System Vacuum and Charge

Using Vacuum Pump

1. Completely tighten all flare nuts and connect manifold gage
charge hose to a charge port of the low side service valve (see
Fig. 12).
2. Connect the charge hose to the vacuum pump.
3. Fully open the low side of manifold gage (see Fig. 13).
4. Start the vacuum pump
5. Evacuate using the triple evacuation method.
6. After evacuation is complete, fully close the low side of mani-
fold gage and stop the vacuum pump operation.
7. The factory charge contained in the outdoor unit is good for up
to 25 ft. (8 m) of line length. For refrigerant lines longer than
25 ft. (8 m), add refrigerant as specified in the ADDITIONAL
REFRIGERANT CHARGE table in this document.
8. Disconnect the charge hose from the charge connection of the
low side service valve.
9. Fully open service valves B and A.
10. Securely tighten the service valves caps.
Refrigerant
Outdoor Unit
A
B
Service Valve
Fig. 12 - Service Valve
Manifold Gage
500 microns
Low side valve
Charge hose
Low side valve
Fig. 13 - Manifold
16
Indoor Unit
Low Side C
D
High Side
High side valve
Charge hose
Vacuum pump
Specifications subject to change without notice.

Deep Vacuum Method

The deep vacuum method requires a vacuum pump capable of pulling a
vacuum of 500 microns and a vacuum gage capable of accurately
measuring this vacuum depth. The deep vacuum method is the most
positive way of assuring a system is free of air and liquid water (see Fig.
14).
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0 1 2
MINUTES
Fig. 14 - Deep Vacuum Graph

Triple Evacuation Method

The triple evacuation method should be used. Refer to Fig. 15 and
proceed as follows:
1. Pump the system down to 1500 microns and allow the pump to
continue operating for an additional 15 minutes.
2. Close the service valves and shut off the vacuum pump.
3. Connect a dry nitrogen cylinder and regulator to the system and
break vacuum until the system reaches 2 psig.
4. Close the service valve and allow the system to stand for 1hr.
During this time, the dry nitrogen can diffuse throughout the
system absorbing moisture.
5. Pump the system down to 1000 microns.
6. Break the vacuum with dry nitrogen (2 psig).
7. Pump the system down to 500 microns.
8. Perform the hold test for 30 minutes.
EVACUATE TO 1500 MICRONS
BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG
EVACUATE TO 1000 MICRONS
BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG
EVACUATE TO 500 MICRONS MINIMUM (HOLD FOR 30 MINUTES)
CHECK FOR TIGHT, DRY SYSTEM
(IF IT HOLDS DEEP VACUUM)
RELEASE CHARGE INTO SYSTEM BY OPENING VALVES COMPLETELY
Fig. 15 - Triple Evacuation Method
Final Tubing Check
IMPORTANT: Check to be certain factory tubing on both indoor
and outdoor unit has not shifted during shipment. Ensure tubes are
not rubbing against each other or any sheet metal. Pay close
attention to feeder tubes, making sure wire ties on feeder tubes are
secure and tight.
LEAK IN
SYSTEM
VACUUM TIGHT
TOO WET
TIGHT
DRY SYSTEM
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