Carrier 38MPRAQ18AA3 - SYSTEM EVACUATION AND CHARGING; Deep Vacuum Method; Triple Vacuum Method

14 Specifications subject to change without notice. SG-38MPRA-02
SYSTEM EVACUATION AND
CHARGING
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
NOTE: DO NOT open the service valves until unit
evacuation procedure is complete.
Using Vacuum Pump
1. Completely tighten all the flare nuts and connect the manifold gage
charge hose to a charge port of the low side service valve (see Fig.
9).
2. Connect the charge hose to the vacuum pump.
3. Fully open the low side of the manifold gage (see Fig. 10).
4. Start the vacuum pump.
5. Evacuate using the triple evacuation method.
6. After the evacuation is complete, fully close the low side of
manifold 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 Charge Table” on
page 13.
8. Disconnect the charge hose from the charge connection of the low
side service valve.
9. Fully open the service valves; B and A.
10. Securely tighten the service valve caps.
Fig. 9 — Service Valve
Fig. 10 — Manifold
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 the vacuum depth. The deep vacuum method is the most
positive way of assuring a system is free of air and liquid water (see
Fig. 11).
Fig. 11 — Deep Vacuum Graph
Triple Vacuum Method
The triple evacuation method should be used. Refer to Fig. 12 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 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.
Fig. 12 —Triple Evacuation Method
Final Tubing Check
IMPORTANT: Ensure that the factory tubing, on both the
indoor and outdoor units, has not shifted during shipment.
Ensure tubes are not rubbing against each other or any
sheet metal. Pay close attention to feeder tubes to ensure
the wire ties on the feeder tubes are secure and tight.
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.
CAUTION
O
utdoor Unit
Indoor Unit
Refrigerant
Service Valve
Gas Side
Liquid Side
A
B
C
D
Manifold Gage
500 microns
Low side valve
High side valve (remains closed)
Charge hose
Vacuum pump
Unit service valve
(requires 5/16" to 1/4"
Schrader adapter for
evacuation/charging)
Low Side Hose
500
MINUTES
01234567
1000
1500
LEAK IN
SYSTEM
VACUUM
TIGHT
TOO WET
TIGHT
DRY SYSTEM
2000
MICRONS
2500
3000
3500
4000
4500
5000
CHECK FOR TIGHT, DRY SYSTEM
(IF IT HOLDS DEEP VACUUM)
EVACUATE TO 1500 MICRONS
EVACUATE TO 500 MICRONS MINIMUM (HOLD FOR 30 MINUTES)
RELEASE
CHARGE INTO SYSTEM BY OPENING
VALVES COMPLETELY
BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG
EVACUATE TO 1000 MICRONS
BREAK VACUUM WITH DRY NITROGEN TO 2 PSIG