Lennox 603364-35 Enthalpy Sensor Kit Installation Guide

IMPORTANT: Two kits must be installed if
differential enthalpy sensing is specified. Check packaging for
shipping damage. Contact the carrier immediately if any shipping
damage is found.

Application

Sensors provide input to determine free cooling suitability. The
enthalpy sensor senses both sensible temperature and humidity.
Refer to the table below for usage.

Installation Instructions

No. Of Sensors

1 Sensor: Outdoor Air Is Enabled For Free Cooling When:

OA enthalpy, A7, is less than free cooling set point (single
enthalpy).

OA enthalpy, A7, is less than RA enthalpy, A62 (differential
enthalpy).

Install Sensors

Disconnect all power to the unit.

Remove the unit top back panel and retain screws. If economizer
is already installed, remove the hood.
Install sensors as shown in the provided table.

Frequently Asked Questions (FAQ)

Q: What should I do if I encounter shipping damage?

A: Contact the carrier immediately if any shipping damage is
found to resolve the issue promptly.

Q: Can I use only one sensor for all applications?

A: No, refer to the table for the number of sensors required
based on the unit and kit harness used.

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ECONOMIZERS

506202-03 8/2025 Supersedes 506202-02

ENTHALPY SENSOR KIT

INSTALLATION INSTRUCTIONS FOR ENTHALPY SENSOR KIT (603364-35; 21Z09) USED WITH ECONOMIZERS

Shipping and Packing List
Package 1 of 1 contains:
1- Sensor 2- #6-32 X 7/8″ Screws 1- P104 Wiring harness (used for outdoor air sensing only) 1- P105 Wiring harness (used for return air sensing only) 1- J105 Wiring harness (KG/KC/KH092-300S only) 1- Bracket (LG/LC/LH/LD/KG/KC/KH 078-152 units only) 1- Wire tie 1- #10-16 X 5/8″ SDST screw IMPORTANT – Two kits must be installed if differential enthalpy sensing is specified. Check packaging for shipping damage. Contact the last carrier immediately if any shipping damage is found.

Application
Sensors provide input to determine free cooling suitability. The enthalpy sensor provided in this kit senses both sensible temperature and humidity. See TABLE 1 for usage.
This kit applies to LGM/LCM, LGT/LCT/LHT/LDT, LGH/ LCH, LGX/LCX/LHX, KG/KC/KH, ZG/ZC/ZH, SCH/ SGH/SHH/SDH, QG/QH/QC unit standard performance economizers and, LGM/LCM/LGH/LCH high performance economizers. A separate kit is used for KG/KC/KH, ZG/ ZC/ZH and QG/QH/QC high performance economizers.
Refer to economizer installation instructions. NOTE – Differential sensor applications must use the same two sensors.

No. Of Sensors
1
2

TABLE 1
Outdoor Air Is Enabled For Free Cooling When:
OA enthalpy, A7, is less than free cooling set point (single enthalpy). OA enthalpy, A7, is less than RA enthalpy, A62 (differential enthalpy).*

Install Sensors
NOTE – Install the return air sensor before installing optional power exhaust dampers and gravity exhaust dampers. If gravity exhaust, power exhaust, or hoods are already installed, remove from unit.
1 – Disconnect all power to unit.
2 – Remove unit top back panel and retain screws. If economizer is already installed, remove hood.
3 – Install sensors as shown in TABLE 2.

Sensors
1
2
1
2
1
2 1 2 1 2 2 2

TABLE 2

Unit

Kit Harness

Used:

LG/LC/LH/LD 024-074

P104

KG/KC/KH 024-090

None*

LG/LC/LH/LD 024-074 P104, P105**

KG/KC/KH 024-090 *P105, J105

LG/LC/LH/LD 078-152

P104

KG/KC/KH 090-150

None*

LG/LC/LH/LD 078-152 P104, P105**

KG/KC/KH 090-150 *P105, J105

LG/LC/LH/LD 156-300

P104

KG/KC/KH 156-300

None**

LG/LC/LH/LD 156-300 P104, P105*

KG/KC/KH 156-300 *P105, J105

ZG/ZC/ZH

None*

***ZG/ZC/ZH

QG/QC/QH

None

***QG/QC/QH

N/A

SC/SG/SH/SD 036-060 P104, P105

SC/SG/SH/SD 092-240 P104, P105

Sensor Location
FIGURE 1
FIGURE 2 and
FIGURE 4
FIGURE 3
FIGURE 5 NA
FIGURE 6 NA
FIGURE 10 FIGURE 11

*P104 not used; disconnect S175, reconnect to A7. **J105 provided in unit. ***Differential enthalpy not available with ZG/ZC/ZH/QG/QC/QH units.

Page 1

WARNING

To prevent serious injury or death:

Lock-out/tag-out before performing mainte-

nance.

If system power is required (e.g., smoke

detector maintenance), disable power to blower,

remove fan belt where applicable, and ensure all

controllers and thermostats are set to the “OFF” po-

sition before performing maintenance.

Always keep hands, hair, clothing, jewelry,

tools, etc., away from moving parts.

WARNING
Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal injury or loss of life. Installation and service must be performed by a qualified installer, service agency or the gas supplier

INSTALL SENSORS LG/LC/LH/LD/KG/KC/KH 024-090 UNITS

A7 OUTDOOR AIR SENSOR

P104 HARNESS (LGH/LCH ONLY)

P105 HARNESS

A62 RETURN AIR SENSOR

INSTALL SENSORS – LG/LC/LH/LD/KG/KC/KH 078-152 UNITS

A7 OUTDOOR AIR SENSOR

P104 HARNESS (LGH/LCH ONLY)

A62 RETURN AIR SENSOR

P105 HARNESS

FIGURE 2

FIGURE 1

Page 2

CAUTION
As with any mechanical equipment, contact with sharp sheet metal edges can result in personal injury. Take care while handling this equipment and wear gloves and protective clothing.

INSTALL SENSORS

P104 HARNESS (LGH/LCH
ONLY)

156-300S UNITS
A7 OUTDOOR AIR SENSOR

J104

DIVISION PANEL

J105 JACK
A6 ENTHALPY CONTROL

P105 HARNESS

A62 RETURN
SOR

INSTALL SENSOR – ZG/ZC/ZH 036-150 UNITS 1- Remove factory-installed S175 outdoor air sensible
sensor and bracket.*
DOWNFLOW
*036-060 SHOWN; 092-150 SIMILAR
2- Disconnect wiring to S175 and reconnect to A7 enthalpy sensor.
3- Install A7 enthalpy sensor using S175 bracket holes. Secure with screws provided in kit.
Note – All contents of kit may be discarded except for the sensor and screws. Harnesses
are not used in this application.
S175
HORIZONTAL

FIGURE 3
INSTALL A62 BRACKET – LG/LC/LH/LD/KG/KC/KH 078-152 UNITS
A7 OUTDOOR AIR SENSOR

DIVISION PANEL

BRACKET

A62 RETURN AIR ENTHALPY SENSOR
FIGURE 4

FIGURE 5
Wire A7 Sensor
NOTE – S175 is factory-installed and wired in KG/KC/ KH/ZG/ZC/ZH/LGX/LCX/LHX 024-300S economizers. Kit P104 harness is not used. When replacing S175 with an A7 enthalpy sensor, wire A7 with disconnected S175 wires.
1 – Connect P104 harness plug to unit J104. See FIGURE 1 for 024-090 units, FIGURE 2 for 078-152 units, and FIGURE 3 for 156-300S units. On SC/SG/ SH/SD see FIGURE 10 for 036-060, FIGURE 11 for 092-240.
NOTE – Wiring to sensor is shown on D or D1 economizer wiring section. D or D1 is located on the compressor access panel or packaged with economizer.
2 – Connect the wires on the other end of the harness to A7 terminals S and + as marked on the wires. Make sure polarity is correct.
Page 3

INSTALL SENSOR – QG/QC/QH 036-150 UNITS

4 – Turn A6 control setpoint dial completely clockwise to position “D”. See FIGURE 7.

Sensor Location

Prodigy 2.0 M3 Unit Controller Configuration
Configure the Unit Controller for the enthalpy sensor using the following menu:
Go to SETUP / INSTALL and navigage through the various setup questions until Configuration ID 1 appears. Position two needs to be set to either S for economizer – single enthalpy or D for economizer – dual enthalpy.

Controller Location
1- Install sensor in the location shown above.
2- Plug the red and black wires from the controllers “SO” and “SO+” terminals into the sensors + and – terminals.
3- Discard unused harnesses.
FIGURE 6
Wire A62 Sensor-LG/LC/LH/LD/KG/KC/KH/ SC/SG/SH/SD
NOTE – Discard J105 harness provided in kit when installing LG/LC/LH/LD & SC/SG/SH/SD units.
1 – Connect P105 harness plug to unit J105. See FIGURE 1 for 024-090 units, FIGURE 2 for 078-152 units, and FIGURE 3 for 156-300S units. On SC/SG/ SH/SD see FIGURE 10 for 036-060, FIGURE 11 for 092-240.
On KG/KC/KH units refer to Wire A6 section in this instruction to install J105. NOTE – Wiring to sensor is shown on D or D1 economizer wiring section. D or D1 is located on the compressor access panel or packaged with economizer. 2 – Connect the wires on the other end of the harness to A62 terminals S and + as marked on the wires. Make sure polarity is correct.
3 – Reinstall gravity exhaust damper, power exhaust, and outdoor air hood when applicable.
Wire A6 Control – KG/KC/KH Units Only
1 – Install J105 harness jack in panel as shown in FIGURE 8 for 024-090 units, FIGURE 9 for KG/KC/KH 090-150 units and FIGURE 3 for 180-300S units.
2 – Remove resistor between A6 enthalpy control terminals SR+ and SR. See FIGURE 7.
3 – Connect the two leads from the wire harness to SR+ and SR terminals on the A6 control. Note the labeling on the wires for correct wiring.

Prodigy M4 Unit Controller Configuration
Configure the unit through the mobile app. Go to SETUP / RTU Menu > Setup Install and navigate through the various setup questions until Configuration ID 1 appears. Position two needs to be set to either S for economizer single enthalpy or D for economizer – dual enthalpy NOTE – Refer to M4 Setup Guide provided with the unit for more info
Operation
Refer to Unit Controller manual for start-up and operation.
A6 CONTROL – KG/KC/KH APPLICATIONS ONLY
EXH Set
2V 10V
EXH

Min Pos Open

REMOVE RESISTOR 2V BETWEEN SR+ AND SR
DCV

SR+ SR

2V Free Cool
B
A

DCV Max
10V
DCV Set
10VROTATE FREE COOL SETPOINT DIAL TO D
C
D

FIGURE 7

Page 4

WIRE A6 ENTHALPY CONTROL KG/KC/KH/LGX/LCX/LHX 024-090 UNITS ONLY

REUSE S175 HARNESS

A7 OUTDOOR AIR SENSOR

PANEL

A62 RETURN AIR SENSOR
P105 HARNESS

A6 ENTHALPY CONTROL

P105 JACK
P105 HARNESS

J105 JACK
A62 RETURN AIR SENSOR

FIGURE 8

WIRE A6 ENTHALPY CONTROL KG/KC/KH 090-150 UNITS ONLY
ROUTE J105 HARNESS THROUGH GROMMET
A6 ENTHALPY CONTROL

P104 HARNESS
J104 J105

S*H 036-060
P104 HARNESS A7 OUTDOOR AIR SENSOR J105
FIGURE 10 S*H 092-240
A7 OUTDOOR AIR SENSOR
A62 RETURN AIR SENSOR P105 HARNESS
FIGURE 11

J105 JACK

FIGURE 9

Page 5

Documents / Resources

Lennox 603364-35 Enthalpy Sensor Kit [pdf] Installation Guide
603364-35, 21Z09, 603364-35 Enthalpy Sensor Kit, 603364-35, Enthalpy Sensor Kit, Sensor Kit, Kit

References

User Manual

Lennox 603364-35 Enthalpy Sensor Kit Installation Guide

603364-35 Enthalpy Sensor Kit

Specifications

Product Usage Instructions

Shipping and Packing List

Application

Installation Instructions

No. Of Sensors

Install Sensors

Frequently Asked Questions (FAQ)

Q: What should I do if I encounter shipping damage?

Q: Can I use only one sensor for all applications?

Documents / Resources

References

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