Installation Requirements; Gas Leak Check With Soap Water; Air And Moisture; Air Purging Using A Vacuum Pump - Lennox MCA Series Service Manual

Y/G
OUTDOOR
MAIN
PCB
BLUE
U
V
RED
W
BLACK
V
U W
COMPRESSOR
Y/G
CN 17 CN 414
DC-FAN
Y/G
Figure 24. 18K and 24K 208/230VAC Outdoor Unit
Wiring Diagram

13. Installation Requirements

13.1. Gas Leak Check with Soap Water:

Apply soap water or a liquid neutral detergent on the
connections with a soft brush to check for leakage in the pipe
connecting points. If bubbles emerge, the pipes are leaking.

13.2. Air and Moisture

Air and moisture in the refrigerant system cause the following
problems:
• Increases in system pressure
• Increases in operating current
• Decreases in cooling and heating efficiency
• Blocks in capillary tubing caused by moisture in the
refrigerant circuit freezing
• Corrosion of parts in the refrigerant system caused by
water
The indoor units and the pipes between indoor and outdoor
units must be tested for leakages and evacuated to remove
gas and moisture from the system.

13.3. Air Purging using a Vacuum Pump

• Completely tighten the flare nuts on the indoor and
outdoor units. Confirm that both the two-way and three-
way valves are set to the closed position.
• Connect the charge hose with the push pin of the
Handle Lo to the three-way valve gas service port.
• Connect the charge hose of the Handle Hi to the
vacuum pump.
• Fully open the Handle Lo of the manifold valve.
• Turn on the vacuum pump to begin evacuation.
Y/G
BLACK 3
BLUE
S
1 2 3 L1L2
Y/G
CN 6 CN 7 CN 8 CN 2
CN 3
3
• Conduct a 30-minute evacuation. Check whether
the compound meter indicates - 0.1Mpa(14.5Psi). If
the meter does not indicate -0.1Mpa (14.5Psi) after
30 minutes has elapsed, continue evacuation for 20
more minutes. If the pressure does not reach - 0.1Mpa
L1 L2
Y/G (14.5Psi) after 50 minutes has elapsed, check if there
are any leaks.
• Fully close the Handle Lo valve of the manifold valve
and turn off the vacuum pump. After five minutes,
confirm that the gauge needle is not moving.
• Turn the flare nut on the three-way valve 45° counter-
clockwise for 6-7 seconds. Once gas begins to come
out, tighten the flare nut. Make sure the pressure
display on the pressure indicator is higher than
atmospheric pressure. Then remove the charge hose
from the three-way valve.
• Fully open the two-way and three-way valves and
securely tighten the cap on the three-way valve.
13.4. Adding Refrigerant if Pipe Length
Exceeds Charge Less Pipe Length
Connect the charge hose to the charging cylinder and open
the two-way and three-way valves. With the charge hose
you disconnected from the vacuum pump, connect it to the
valve at the bottom of the cylinder.
If the refrigerant is R-410A, place the cylinder bottom-up to
ensure liquid charging is possible.
• Purge the air from the charge hose.
• Open the valve at the bottom of the cylinder and press
the check valve on the charge set (be careful of the
liquid refrigerant).
• Place the charging cylinder onto the electronic scale
and record the weight.
• Turn on the air conditioner in cooling mode.
• Open the valves (Low side) on the charge set. Charge
the system with liquid refrigerant.
• When the electronic scale displays the proper weight
(refer to the table), disconnect the charge hose from
the three-way valve's service port immediately and turn
off the air conditioner before disconnecting the hose.
• Mount the valve stem caps and the service port Use
a torque wrench to tighten the service port cap to a
torque of 18N.m (13.27 ft·lbs).
• Be sure to check for gas leaks.
13.5. Add Refrigerant after Long-Term
System Operation
• Connect the charge hose to the three-way service port
and open the two-way and three-way valve.
• Connect the charge hose to the valve at the bottom
of the cylinder. If the refrigerant is R-410A, place the
cylinder bottom-up to ensure liquid charge.
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