System Evacuation And Charging - Carrier 40MBDAQ Service Manual

40MBDAQ: 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. The alternate triple
evacuation method may be used if the following procedure is followed.
Always break a vacuum with dry nitrogen.
System Vacuum and Charge
Using Vacuum Pump
1. Completely tighten the flare nuts (A, B, C, D, E). Fully open all
circuits service valves. Connect the manifold gage charge hose to the
charge port of the low side Master service valve to evacuate all
circuits at the same time (see Fig. 10).
2. Connect the charge hose to the vacuum pump.
3. Fully open the low side of the manifold gage (see Fig. 11).
4. Start the vacuum pump.
5. Evacuate using the triple evacuation method.
6. After the evacuation is complete, fully close the low side of the
manifold gage and stop the vacuum pump operation. The factory
charge contained in the outdoor unit is good for up to 25 ft. (8 m) of
line length.
7. Disconnect the charge hose from the charge connection of the low
side service valve.
8. Fully open the service valves (B and A).
9. Securely tighten the service valve caps.
Outdoor Unit
A
B
Service Valve
Fig. 10 — Service Valve
Manifold Gage
500 microns
Low side valve
Charge hose
Low side valve
Fig. 11 — Manifold
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Refrigerant Indoor Unit
Low Side C
D
High Side
High side valve
Charge hose
Vacuum pump
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
ensuring a system is free of air and liquid water (see Fig. 12).
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Fig. 12 — Deep Vacuum Method
Triple Evacuation Method
The triple evacuation method should be used. Refer to Fig. 13 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 the vacuum until the system reaches 2 psig.
4. Close the service valve and allow the system to stand for one hour.
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.
BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG
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BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG
EVACUATE TO 500 MICRONS MINIMUM (HOLD FOR 30 MINUTES)
CHECK FOR TIGHT, DRY SYSTEM
RELEASE CHARGE INTO SYSTEM BY OPENING VALVES COMPLETELY
Fig. 13 — Triple Evacuation Method
Final Tubing Check
IMPORTANT: Check to ensure the factory tubing on both the
indoor and outdoor unit has not shifted during the shipment.
Ensure the tubes are not rubbing against each other or any
sheet metal. Pay close attention to feeder tubes, ensuring the
wire ties on the feeder tubes are secure and tight.
A220979
8
LEAK IN
SYSTEM
VACUUM TIGHT
TOO WET
TIGHT
DRY SYSTEM
1 2 3 4 5 6 7
MINUTES
EVACUATE TO 1500 MICRONS
EVACUATE TO 1000 MICRONS
(IF IT HOLDS DEEP VACUUM)
A220980
A220981