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Corp. 1244-L9
connector at the nitrogen cylinder. When the system
pressure is reduced to normal, disconnect the hose
from the cylinder.
EVACUATION
1. Connect the gauge set, micron gauge and vacuum
pump as shown in figure 40.
2. The operation time for evacuation varies with the line
set length and capacity of the pump. Allow the pump to
operate until the system has been evacuated down to
300 microns. Allow the pump to continue running for an
additional 15 minutes.
3. Turn off the pump and leave the connections secured
to the 3-way service valve. After five minutes, if the
system fails to hold 500 microns or less, check all
connections for tight fit and repeat the evacuation
procedure.
4. When the desired vacuum is reached, close the low
knob of the manifold valve and stop the vacuum pump.
Unit Start-Up
IMPORTANT
If unit is equipped with a crankcase heater, it should be
energized 24 hours before unit start-up to prevent
compressor damage as a result of slugging.
UNIT START-UP
1. Inspect all factory- and field-installed wiring for loose
connections.
2. Verify that the manifold gauge set is connected as
illustrated in figure 40.
3. Open the 3-way service and two-way shut off valves to
release the refrigerant charge contained in outdoor unit
into the system.
4. Replace the stem caps and tighten to the value listed
in table 5.
5. Check voltage supply at the outdoor unit terminal strip.
The voltage must be within the range listed on the unit's
nameplate. If not, do not start the equipment until you
have consulted with the power company and the
voltage condition has been corrected.
6. Refer to the included user guide to operate the system
using the provided remote control.
7. Visually check for binding of both indoor and outdoor
fans.
Adding Refrigerant for Longer Line Set
IMPORTANT
FV50S PVE is the ONLY acceptable oil for Lennox MS7
and MS8 mini-split systems.
Polyvinylether (PVE) is an innovative refrigerant oil
specially formulated for hydrofluorocarbon (HFC)
refrigeration systems. In addition to providing lubricating
properties, it also has a number of other applied
advantages that help to increase the reliability of the
refrigeration systems where it is applied.
1. Open the low side manifold gauge valve and weigh in
liquid refrigerant. Use table 12 to calculate the correct
weigh-in charge.
2. Close manifold gauge valves.
Table 11. Line Set Length and Adding Refrigerant
System
Size
(kBtu)
Base Charge (outdoor
unit is sufficient for up
to listed length below)
Add Refrigerant
-09
26 feet (8 m)
1 ounces per 40 inches (30
grams per meter)
-12
-18
0.71 ounces per 40 inches
(20 grams per meter)
-24
1 ounces per 40 inches (30
grams per meter)
-30
2 ounces per 40 inches (50
grams per meter)
Checking Large Line Operating Pressures
Connect gauge set to service port as illustrated in figure 40.
1. Indoor temperatures should be between 70F and 86F
(21C and 30C). Outdoor temperatures should be
between 23F to 118F (-5C to 48C).
2. Turn the remote control I FEEL function ON.
3. Set all indoor zone remote controls to lowest setting
61F {16C} in the Cool mode.
4. Turn ON the TURBO function. (Note: Allow 3 minutes
for compressor delay to time out).
5. Allow the system to operate for a minimum of 10
minutes before doing system checks: Indoor air coil
temperature drop (Range of 18 to 24F (10 to 13C).
Refrigerant pressure on big line. (Use pressure
ranges noted in table 12 for general guides. Minor
variations in these pressures may be expected due
to differences in installations).
HEATING
1. Indoor temperatures should be between 61F and 70F
(16C and 21C). Outdoor temperatures should be
between 5F to 80F (-15C to 27C)
2. Set all indoor zone remote controls to highest setting
86F {30C} in the Heat mode.
3. Turn the remote control I FEEL function ON.
4. Turn ON the TURBO function. (Note: Allow 3 minutes
for compressor delay to time out).
5. Allow the system to operate for a minimum of 10
minutes before doing system before checking:
Refrigerant pressure on big line. (Use pressure
ranges noted in table 12 for general guides. Minor
variations in these pressures may be expected due
to differences in installations).
IMPORTANT
If the operating pressures do not fall within the ranges given
in the pressure table:
A. Check the indoor or outdoor unit displays for error
code(s).
B. Refer to troubleshooting procedure diagrams in
Service and Installation manual to verify
component operation.
If no issues are found, follow the weigh-in charging
procedure below to charge the system.
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