Carrier 69NT40-541-505 Operation And Service Manual Download Page 97

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7–5

T-368

7.7.1

Checking the Refrigerant Charge

NOTE

To avoid damage to the earth’s ozone layer,
use a refrigerant recovery system whenever
removing refrigerant. When working with
refrigerants you must comply with all local
government environmental laws. In the U.S.,
refer to EPA section 608.

a. Connect the gauge manifold to the compressor

discharge and suction service valves.

b. Bring the container temperature to approxi-

mately 1.7°C (35°F) or -17.8°C (0°F). Set the
controller set point to -25°C (-13°F) to ensure
that the suction modulation valve is at maximum
allowed open position.

c. Partially block the condenser coil inlet air. If cov-

ering the lower portion of the coil is not sufficient,
remove the left hand infill panel and cover the left
side of the coil. Increase the area blocked until
the compressor discharge pressure is raised to
approximately 12.8 bar (185 psig).

d. On the receiver, the level should be between the

glasses. If the refrigerant level is not correct,
continue with the following paragraphs to add or
remove refrigerant as required.

7.7.2

Adding Refrigerant to System (Full
Charge)

a. Evacuate unit and leave in deep vacuum (refer

Section 7.6

b. Place cylinder of R-134a on scale and connect

charging line from cylinder to liquid line valve.
Purge charging line at liquid line valve and then
note weight of cylinder and refrigerant.

c. Open liquid valve on cylinder. Open liquid line

valve half-way and allow the liquid refrigerant to
flow into the unit until the correct weight of refrig-
erant (refer to

Section 3.2

) has been added as

indicated by scales.

NOTE

It may be necessary to finish charging unit
through suction service valve in gas form,
due to pressure rise in high side of the sys-
tem (refer to

Section 7.7.3

d. Backseat manual liquid line valve (to close off

gauge port). Close liquid valve on cylinder.

e. Start unit in cooling mode. Run approximately

10 minutes and check the refrigerant charge.

7.7.3

Adding Refrigerant to System (Partial
Charge)

a. Examine the unit refrigerant system for any evi-

dence of leaks. Repair as necessary (refer to

Section 7.5

b. Maintain the conditions outlined in

Section 7.7.1

c. Fully backseat the suction service valve and

remove the service port cap.

d. Connect charging line between suction service

valve port and cylinder of refrigerant R-134a.
Open VAPOR valve.

e. Partially frontseat (turn clockwise) the suction

service valve and slowly add charge until the
refrigerant appears at the proper level.

7.8

COMPRESSOR

WARNING

Make sure power to the unit is OFF and
power plug disconnected before replac-
ing the compressor.

NOTES

1. The compressor should not operate in a vacuum

greater than 500mm/hg (20 inches/hg).

2. The service replacement compressor is sold

without shutoff valves (but with valve pads), and
without terminal box and cover. Customer
should retain the original terminal box, cover,
and high pressure switch for use on replace-
ment compressor.

3. Check oil level in service replacement compres-

sor (refer to

Section 7.8.6

4. A compressor terminal wiring kit must be

ordered as a separate item when ordering
replacement compressor. Appropriate installa-
tion instructions are included with kit.

5. Refer to

Table 7–4

an d

Table 7–5

for applicable

compressor wear limits and torque values.

6. Refer to