Lennox Industries Inc 68M04 Low Ambient Control Kit Instruction Manual

Litho U.S.A.
KITS COMMON TO COOLING AND HEAT PUMP UNITS
LOW AMBIENT CONTROL KIT

68M04 Low Ambient Control Kit

INSTALLATION INSTRUCTIONS FOR LOW AMBIENT CONTROL KIT (68M04) USED WITH VARIABLE SPEED FAN OUTDOOR UNITS
WARNING
Improper installation, adjustment, alteration, service or maintenance can cause personal injury, loss of life, or damage to property.
Installation and service must be performed by a licensed professional installer (or equivalent) or a service agency.
CAUTION
Physical contact with metal edges and corners while applying excessive force or rapid motion can result in personal injury. Be aware of, and use caution when working nearby these areas during installation or while servicing this equipment.
WARNING
Electric Shock Hazard. Can cause injury or death. Unit must be grounded in accordance with national and local codes.
Line voltage is present at all components when unit is not in operation on units with single‐pole contactors. Disconnect all remote electric power supplies before opening access panel. Unit may have multiple power supplies.

Shipping and Packing List

Kit 68M04 contains the the following parts:
1 — Low ambient pressure switch assembly (S11) 1 each — K58 and K159 relays
10 — 20” Lengths of wire (c/w 3/16” female quick connects on one end of each wire)
10 — Wire nuts
4 — #10-16 X 5/8” S.D.S.T. screws
1 — Schrader® depressor tee with seal cap

Additional Parts Required

1. All units will require one field-provided properly sized freezestat (S49) for use with this kit. Order part using table 1.
   Table 1. Freezestat Selection (S49)Tubing Size| Wire Length| Wire Gauge| Lennox Catalog Number| Freezestat Set Points
   ---|---|---|---|---
   Open| Close
   3/8″| 90-13/16″| 18| | 93G35 29°F (-2° C)| 58°F (10°C)
   5/8″| 36-1/2″| 18| | 50A93 36°F (2°C)| 58°F (10°C)
2. Use ONLY expansion valve metering devices on units with low ambient kits. Refer to the heat pump’s Production Specification bulletin to order the required expansion valve for the indoor coil.

Application

NOTE — This kit may be used in expansion valve systems only. It is not suitable for use in systems using either piston-type or capillary tube metering devices.
NOTE — All units reference in this instruction are factory-equipped with a crankcase heater.
NOTE — This kit is suitable only for use in HFC-410A refrigerant applications.
The low ambient control pressure switch S11 cycles the outdoor fan, while allowing continuous compressor operation during a cooling demand. This intermittent outdoor fan operation maintains a minimum pressure differential across the expansion device as the ambient temperature drops, thus reducing capacity losses during low ambient conditions. The freezestat (ordered separately) senses suction line temperature and cycles the compressor off when suction line temperature falls below its setpoint. This kit is designed for use in ambient temperatures that are no lower than 30°F (-1°C) unless otherwise noted in the Product Specification bulletin.

Installation

LOW AMBIENT PRESSURE SWITCH (S11)
The provided low ambient pressure switch is factory set for 450 psig (3100 kPa) cut-in and 240 psig (1600 kPa) cut-out. This switch is not adjustable.
NOTE — Use ONLY expansion valve metering devices on units with low ambient kits.

1. Turn off the electrical power to the unit.

2. Remove compressor compartment access panel, if applicable.

3. Install provided low ambient pressure switch on open port (no valve core) of provided tee fitting (see figure 1 for example).
   NOTE — Pressure switch must be installed on tee first. Then install tee on liquid line service port to avoid refrigerant loss.

4. Install tee fitting on outdoor unit liquid line service port.

5. Install seal cap on tee valve core port and tighten to 6 to 8 ft.-lbs. When a torque wrench is not available, finger tighten and use an appropriately sized wrench to turn an additional 1/6 turn clockwise.

6. Route pressure switch wires to control box and connect using applicable unit wiring diagram.

RELAYS (K58 and K159)
Depending on the specific model unit, one of the provided relays will be used (see figure 1 for relay(s) installation location).

FREEZESTAT (S49)
The freezestat (ordered separately) will open and close at the non-adjustable set points listed in table 1.
Installation Method 1 — (Non-Communicating Unit)

1. A freezestat, sized per table 1 and ordered separately, must be installed. Install the freezestat on one of the copper lines between the last hairpins and the suction manifold (see figure 2) of the indoor coil.
2. The freezestat senses the line temperature and cycles the compressor off when the line temperature fails below its setpoint. The freezestat will open and closed as listed in table 1.
3. Connect freezestat (S49) wires as exampled in the applicable unit wiring diagrams.

CAUTION
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS AND PROCEDURES
Electrostatic discharge can affect electronic components. Take care during unit installation and service to protect the unit’s electronic controls. Precautions will help to avoid control exposure to electrostatic discharge by putting the unit, the control and the technician at the same electrostatic potential. Touch hand and all tools on an unpainted unit surface before performing any service procedure to neutralize electrostatic charge.
Installation Method 2 — (Communicating Unit)
This installation method is applicable to the models listed below.

1. A freezestat, sized per table 1 and ordered separately, must be installed. Install the freezestat near last bend (tube) of the indoor coil before the suction manifold (see figure 2).
2. The freezestat senses the line temperature and cycles the compressor off when the line temperature fails below its setpoint. The freezestat will open and closed as listed in table 1.
3. Connect freezestat (S49) wires as exampled in the applicable unit wiring diagrams and figure 3.

Wire Connections

Complete the wiring connections per the appropriate wiring diagram (figures 6 through 14).

Operational Checkout

COOLING MODE

• Set the room thermostat to call for cooling.
• The unit will receive a Y signal from the room thermostat through the field mounted freeze thermostat.
• The compressor will cycle ON.
• The outdoor fan will be OFF until the liquid line pressure reaches the ON setting (450 psig – 3100kPa) of the low ambient pressure switch.
• The low ambient pressure switch S11 contacts will close, and the K159 relay coil will be energized.
• K159-1 relay contacts will close, and the outdoor fan motor will cycle ON.

NOTE — The outdoor fan motor will be cycled by the low ambient and K159 relay. During a call for cooling when the liquid line pressure rises above 450 psig (3100 kPa), the outdoor fan will cycle ON. When the liquid line pressure falls below 240 psig (1600 kPa), the outdoor fan will cycle OFF.

• Set the room thermostat to call for cooling.
• The defrost control in the unit will receive a Y and O signal from the room thermostat.
• The O signal will energize the reversing valve and the K58 relay coil. Contact K58-1 will open.
• The Y signal will go through the freezestat to Y1 on the defrost control.
• The signal will go into defrost control to the HI-PS terminals, out to the high pressure switch and discharge thermostat, then back to the other HI-PS terminal.
• The signal will come back out of the defrost control on the Y terminal, which will energize the compressor contactor coil. The compressor will cycle ON.
• The outdoor fan motor will be OFF until the liquid line pressure reaches the setting of the low ambient pressure switch (450 psig – 3100kPa).
• The low ambient pressure switch will close and K159 relay coil will be energized.
• K159-1 contacts will close and the outdoor fan motor will cycle ON.

NOTE — The outdoor fan motor will be cycled by the low ambient and K159 relay. During a call for cooling when the liquid line pressure rises above 450 psig (3100 kPa), the outdoor fan will cycle ON. When the liquid line pressure falls below 240 psig (1600 kPa), the outdoor fan will cycle OFF.
HEATING MODE

• Set the room thermostat to call for heating.
• The defrost control in the unit will receive a Y signal from the room thermostat.
• The O signal from the room thermostat is not energized, so the K58 relay coil will not be energized. Contact K58-1 will remain closed.
• The Y signal will go through the freezestat to Y1 on the defrost control.
• The signal will go into defrost control to the HI-PS terminals, out to the high pressure switch and discharge thermostat and back to the other HI-PS terminal.
• The signal will come back out of the defrost control on the Y terminal which will energize the compressor contactor coil. The compressor will cycle ON.
• The K58-1 relay contacts (which are normally closed) will prevent the low ambient pressure switch from interrupting the outdoor fan motor operation during the heating mode.

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