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 procedure outlined below is followed. Always break a vacuum with dry nitrogen.

SYSTEM VACUUM AND CHARGE

Using Vacuum Pump

1.Completely tighten flare nuts A, B, C, D, connect manifold gage charge hose to a charge port of the low side service valve. (See Fig. 15.)

2.Connect charge hose to vacuum pump.

3.Fully open the low side of manifold gage. (See Fig. 16)

4.Start vacuum pump

5.Evacuate using either deep vacuum or triple evacuation method.

6.After evacuation is complete, fully close the low side of manifold gage and stop operation of vacuum pump.

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 0.1 oz. per foot of extra piping up to the maximum allowable length.

8.Disconnect charge hose from charge connection of the low side service valve.

9.Fully open service valves B and A.

10.Securely tighten caps of service valves.

Outdoor Unit

Refrigerant

Indoor Unit

Low Side

C

A

 

 

D

B

High Side

 

Service Valve

 

 

 

 

A07360

Fig. 15 – Service Valve

 

Manifold Gage

 

500 microns

 

 

Low side valve

High side valve

Charge hose

Charge hose

 

 

 

Vacuum pump

Low side valve

A07361

Fig. 16 – 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 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. 17)

5000

 

 

 

 

 

 

 

4500

 

 

 

 

 

 

 

4000

 

 

 

 

 

LEAK IN

3500

 

 

 

 

 

 

 

 

 

 

SYSTEM

3000

 

 

 

 

 

 

 

 

 

 

 

 

2500

 

 

 

 

 

 

 

MICRONS2000

 

 

 

 

 

VACUUM TIGHT

1500

 

 

 

 

 

 

 

 

 

 

TOO WET

1000

 

 

 

 

 

 

 

 

 

 

TIGHT

500

 

 

 

 

 

 

 

 

 

 

DRY SYSTEM

 

 

 

 

 

 

0

1

2

3

4

5

6

7

 

 

 

MINUTES

 

 

 

 

 

 

 

 

 

 

A95424

Fig. 17 – Deep Vacuum Graph

Triple Evacuation Method

The triple evacuation method should only be used when vacuum pump is only capable of pumping down to 28 in. of mercury vacuum and system does not contain any liquid water.

Refer to Fig. 18 and proceed as follows:

1.Pump system down to 28 in. of mercury and allow pump to continue operating for an additional 15 minutes.

2.Close service valves and shut off vacuum pump.

3.Connect a nitrogen cylinder and regulator to system and open until system pressure is 2 psig.

4.Close service valve and allow system to stand for 1 hr. Dur- ing this time, dry nitrogen will be able to diffuse throughout the system absorbing moisture.

5.Repeat this procedure as indicated in Fig. 18. System will then be free of any contaminants and water vapor.

EVACUATE

BREAK VACUUM WITH DRY NITROGEN

WAIT

EVACUATE

BREAK VACUUM WITH DRY NITROGEN

WAIT

EVACUATE

CHECK FOR TIGHT, DRY SYSTEM (IF IT HOLDS DEEP VACUUM)

RELEASE CHARGE INTO SYSTEM

A95425

Fig. 18 – 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.

38/40MVC, MVQ

19

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Carrier 40MVQ, 40MVC, 38MVQ, 38MVC service manual System Evacuation and Charging, Using Vacuum Pump
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