Lennox AC13 -018 Installation Instructions Manual Download Page 15

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Page 15

AC13 SERIES

high pressure gauge to

liquid

line service valve

2. Connect micron gauge.
3. Connect the vacuum pump (with vacuum gauge) to

the center port of the manifold gauge set.

4. Open both manifold valves and start the vacuum

pump.

5. Evacuate the line set and indoor unit to an

absolute

pressure

of 23,000 microns (29.01 inches of

mercury).

NOTE − During the early stages of evacuation, it is
desirable to close the manifold gauge valve at least once to
determine if there is a rapid rise in sure indicates a
relatively large leak. If this occurs,

repeat the leak testing

procedure

NOTE − The term

absolute pressure

means the total

actual pressure within a given volume or system, above
the absolute zero of pressure. Absolute pressure in a
vacuum is equal to atmospheric pressure minus vacuum
pressure.

6. When the absolute pressure reaches 23,000 microns

(29.01 inches of mercury), close the manifold gauge
valves, turn off the vacuum pump and disconnect the
manifold gauge center port hose from vacuum pump.
Attach the manifold center port hose to a dry nitrogen
cylinder with pressure regulator set to 150 psig (1034
kPa) and purge the hose. Open the manifold gauge
valves to break the vacuum in the line set and indoor
unit. Close the manifold gauge valves.

7. Shut off the dry nitrogen cylinder and remove the

manifold gauge hose from the cylinder. Open the
manifold gauge valves to release the dry nitrogen from
the line set and indoor unit.

8. Reconnect the manifold gauge to the vacuum pump,

turn the pump on, and continue to evacuate the line set
and indoor unit until the absolute pressure does not
rise above 500 microns (29.9 inches of mercury) within
a 20−minute period after shutting off the vacuum pump
and closing the manifold gauge valves.

9. When the absolute pressure requirement above has

been met, disconnect the manifold hose from the
vacuum pump and connect it to an upright cylinder of
HCFC−22 refrigerant. Open the manifold gauge valve
1 to 2 psig in order to release the vacuum in the line set
and indoor unit.

10. Close manifold gauge valves and shut off the

HCFC−22 cylinder and remove the manifold gauge
set

Servicing Unit Delivered Void of Charge

If the system is void of refrigerant, clean the system using
the procedure described below.

1. Use nitrogen to pressurize the system and check for

leaks. Repair all leaks.

2. Evacuate the system to remove as much of the

moisture as possible.

3. Use nitrogen to break the vacuum and install a liquid

line filter drier in the system.

4. Evacuate the system again. Then, weigh the

appropriate amount of HCFC−22 refrigerant as listed
on unit nameplate into the system.

5. Monitor the system to determine the amount of

moisture remaining in the oil. It may be necessary to
replace the filter drier several times to achieve the
required dryness level.

If system dryness is not

verified, the compressor will fail in the future.

Electrical Connections

In the U.S.A., wiring must conform with current local codes
and the current National Electric Code (NEC). In Canada,
wiring must conform with current local codes and the current
Canadian Electrical Code (CEC).

Refer to the furnace or blower coil installation instructions
for additional wiring application diagrams and refer to unit
nameplate for minimum circuit ampacity and maximum
over−current protection size.

NOTE − To facilitate conduit, a hole is in the bottom of the
control box. Connect conduit to the control box using a
proper conduit fitting.

NOTE − Units are approved for use only with copper
conductors.

NOTE − 24V, Class II circuit connections are made in the
low voltage junction box. See figure 30 for field wiring
diagram.

NOTE − For proper voltages, select thermostat wire gauge
per the following chart:

Table 3. Wire Run Lengths

Wire run length

AWG #

Insulation type

less than 100’ (30m)

color−coded, temperature
rating 35

C minimum

more than 100’ (30m)