Introduction and Overview
This manual provides installation and setup instructions for the Lennox Low Global Warming Potential (GWP) Refrigerant Detection System (RDS) Non-Communicating Control Board (24 Volt Only). The RDS ensures safe operation of Lennox residential HVAC systems equipped with R-454B refrigerant.
The RDS connects to the refrigerant detection sensor, the indoor unit, the outdoor unit, and the thermostat to control the HVAC system if refrigerant is detected. It functions with standard 24VAC or Lennox-communicating control interfaces.
Twinning of furnaces is not permitted with the Refrigerant Detection System Kit.
The RDS activates the blower if refrigerant levels within the cabinet reach 12% of the lower flammability limit (LFL). The UL standard is 25% of the LFL.
Power to all ignition sources within the HVAC system is automatically shut down until the RDS detects safe refrigerant levels. It restores power after concentrations are safe, and the HVAC system resumes normal operation.
Safety Information
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 licensed professional HVAC installer or service agency.
WARNING: All systems charged with at least 4 lbs of R-454B refrigerant are required to have a refrigerant detection system installed to prevent the build-up of R-454B refrigerant in enclosed spaces. A system may be required for systems with less than 4 lbs. Contact Lennox Technical Support for more information. Installing a residential HVAC system with R-454B refrigerant without a detection system may lead to a fire hazard in the event of a refrigerant leak.
WARNING: The Lennox® RDS Non-Communicating Control Board has been tested with Lennox® coils only. Do not use a non-Lennox refrigerant detection system controller or sensor with Lennox® coils. Do not use the control board with non-OEM coils or air handlers.
WARNING: Improper installation of the RDS Non-Communicating Control Board may lead to unreliable equipment operation and unreliable refrigerant detection. Consider sensor mounting location carefully; refer to respective Lennox air handler, coil, and/or sensor kit installation guides.
CAUTION: It is the responsibility of the licensed installer or service agency to obtain appropriate training and/or certifications to service A2L-classified HVAC systems with R-454B refrigerants.
CAUTION: Unit must remain powered except during service.
Certifications
- CSA C22.2 No. 60335-2-40:22; Fourth ed.
- UL 60355-2-40; Fourth ed.
Shipping and Packing List
| Qty | Description | Cat. No. |
|---|---|---|
| 1 | Lennox® Low GWP Refrigerant Detection System | 27A02 |
| 2 | Mounting Hardware - #6-18 1" Phillips Drive pan head with dry wall anchor | N/A |
This kit is sold separately from the refrigerant detection sensor. The sensor is included as part of a Lennox sensor kit, R-454B-only coil, or R-454B-only air handler.
Operating Environment Specifications
The Low GWP Refrigerant Detection Kit is designed to withstand the following conditions:
| Condition | Temperature Range |
|---|---|
| Normal Operation | -40°F - 185°F (40°C - 85°C) |
| Shipping/Storage | -40°F - 185°F (40°C - 85°C) |
| Condition | Functional Range |
|---|---|
| Humidity | 10% to 90% non-condensing at 104°F (40°C) |
Product Features
- Detects unsafe levels of R-454B refrigerant and prevents refrigerant from reaching the lower flammability limit, should a leak occur in the indoor coil.
- Multicolor LED (light-emitting diode) communicates the state of the RDS Non-Communicating Control Board.
- Test/Reset button to verify the functionality of the RDS Non-Communicating Control Board.
- Composite case with mounting hardware for drywall installation.
- Supports a maximum of two refrigerant detection sensors.
- Supports standard 24VAC control split HVAC equipment (Single-Stage, Two-Stage, Variable Speed, Heat Pump, AC, Gas Furnace, Air Handler); refer to "Thermostat Compatibility".
- Compliant with UL-60355-2-40 & CSA.
- Compatible with OEM approved sensor.
A refrigerant detection system must be installed on an outdoor unit that requires R-454B refrigerant. Some indoor units may already feature refrigerant detection control functionality and may not require this kit; contact Technical Support for more information.
Dimensions
The RDS Non-Communicating Control Board has the following dimensions:
- Top View: 7-7/16 in. (189 mm)
- Side View: 7-7/16 in. (189 mm) height, 2-1/2 in. (127 mm) depth.
- Front View: 6-3/4 in. (171.5 mm) width and height.
- Rear View: 3-5/8 in. (92.1 mm) width and height.
- Bottom View: 1-3/8 in. (34.9 mm) height from mounting surface, 1-1/8 in. (28.6 mm) depth from mounting surface.
Installation
Sensor Part Number Verification
Verify the refrigerant detection system sensor's part number, found on the sensor/cable, prior to installation. The part number is 107648-01.
All sensors paired to a single RDS Non-Communicating Control Board must share the same part number (107648-01) to ensure proper function.
Mounting Methods
Some mounting surfaces may be difficult to access after installation. Wire the RDS Non-Communicating Control Board prior to mounting in a confined space.
For drywall/closet installations, use the included drywall hardware. For attic/crawlspace/basement installations, use the included and field-provided hardware.
Mounting Location
The RDS Non-Communicating Control Board can be mounted to the indoor unit, plenum, a stud, or joist in an attic, crawlspace, or other unfinished area within 48 inches of the refrigerant sensor cable grommet on the coil or air handler. Drywall anchors and screws are provided for installation in finished areas, such as closets.
Mount the control board in a clean, dry environment away from dust, water, and other contaminants.
Mounting the control board farther than 48 inches from the sensor may prevent reliable operation due to cable strain and water seepage on cable connections.
- Do not place the RDS Non-Communicating Control Board in the secondary drain pan.
- Use the provided screws to mount the control board.
- Tighten the screws to a snug fit.
Do not over-tighten the screws, as this may strip the hardware and apply excessive stress on the enclosure.
Refrigerant Detection System Sensor
(Sold separately)
The RDS sensor must be mounted as specified in its accompanying manual. Incorrect mounting or location may result in refrigerant detection failure.
Condensate Safety Switch (Float Switch)
If a condensate safety switch is required, it must be wired between the room thermostat and the Refrigerant Detection System. The float switch's normally closed contacts can interrupt the "R" or "Y" wire between the thermostat and the RDS Non-Communicating Control Board. This ensures the control board remains powered continuously and operates normally.
Do not wire the condensate safety switch or other field-installed safety switches between the indoor unit transformer and the RDS Non-Communicating Control Board. The control board must remain powered at all times.
Refrigerant Detection System Sensors
The Lennox Refrigerant Detection System requires a Lennox RDS sensor located in the indoor coil. See table below.
| Indoor Unit Model | RDS Control Board Sensor Catalog Number | Description |
|---|---|---|
| • CK40CT Upflow • CK40HT Horizontal • CK40DT Downflow "Revision 01" Coils • CBK45UHPT • CBK45UHET • CBK45UHVT • CK47UHET "Revision 01" Air Handlers | 26Z69 | Refrigerant Detection System Coil Sensor Kit |
| • CK40CT Upflow, • CK40HT Horizontal, • CK40DT Downflow "Revision 71" Coils | 27J27 | Refrigerant Detection System Air Handler Sensor Kit |
| All Lennox R-454B Coils & Air Handlers | Factory Installed | RDS Sensor is Factory Installed in "Revision 71" Coils |
| All Lennox R-454B Coils & Air Handlers | 27V53 | Coil Sensor Repair Kit (Replacement Sensor only, without mounting bracket & components provided in the Sensor Kit) |
Routing the Sensor Cable
Figure 3 illustrates how to best route the sensor cable from the RDS Non-Communicating Control Board to the sensor within the indoor unit for Upflow, Downflow, and Horizontal orientations. Refer to the respective sensor kit, air handler, or coil installation guide for details on mounting the sensor itself.
Diagram Description (Figure 3): Shows three diagrams illustrating sensor cable routing for different indoor unit orientations: Upflow, Downflow, and Horizontal. Each diagram shows the RDS unit, the coil, and the sensor cable being routed from the control board to the coil area, with a "drip loop" and a "sensor cable drill out" point indicated.
WARNING: Do not strap the RDS Non-Communicating Control Board to existing tubing or other electrical cables.
Connecting the RDS Sensor
Ensure the cable is properly connected into the number one (1) sensor plug. The Molex plug clip should lock into the Molex connection point for a secured connection, as shown in Figure 4. Verify the connection is free of dust, debris, and moisture.
Diagram Description (Figure 4): A close-up view of the RDS Non-Communicating Control Board showing the "SENSOR" connection point. An arrow points to the Molex plug clip, indicating where the sensor cable connects. The image displays the electronic components on the board.
Secondary Sensor
Additional Line Set Joints
If additional joints are present outside of the line set sleeve, the system installation must comply with one of the options listed. Refer to Refrigerant Detection Sensor Kit Installation Instructions Form# (508467-01).
Multiple Systems Installed in Same Space
For any Low GWP refrigerant system with additional joints not covered by line set joint sleeves, each system in the same space must have a refrigerant detection sensor installed below the level of the burners.
If a secondary refrigerant sensor is required, it must be mounted as follows:
- Upflow Applications: Mounted on an unused side furnace return air connection at least nine (9) inches above the floor and within nine (9) inches from the front of the furnace.
- Horizontal Applications: Mounted on the lower section of the side return furnace air connection, within nine (9) inches of both the blower deck and front of furnace.
- Downflow Applications: Mounted on one side of the evaporator coil nine (9) inches above the floor and within nine (9) inches from the front of the coil.
Connect the refrigerant sensor to the second sensor input on the RDS Control. Refer to the instructions provided with the RDS sensor or the RDS controller to enable the second sensor (see "DIP Switch Settings" on page 12).
DIP Switch Settings
Default Switch DIP Settings
The default DIP switch settings are:
- DIP Switch 1 → OFF
- DIP Switch 2 → OFF
The default setting requires the RDS Control Board to have two (2) sensors installed.
The sensor settings must be adjusted according to the number of sensors installed. If a second sensor is not installed (in Sensor 2 plug), DIP Switch 2 must be turned to the ON position.
Non-Default Configurations
Adjust the DIP switch settings to match the sensor configuration. Failure to do so will cause faults upon powering-up.
| Configuration | DIP1 | DIP2 |
|---|---|---|
| One (1) sensor, connected to SENSOR 1 plug | OFF | ON |
| Two (2) sensors, connected to SENSOR 1 plug and SENSOR 2 plug | OFF | OFF |
Configurations other than those shown in "Table 1. DIP Switch Settings" will cause a service fault.
Each DIP switch corresponds to a sensor position (e.g., DIP switch 1 to sensor 1; DIP switch 2 to sensor 2). The default factory switch positions are set to OFF. The RDS Non-Communicating Control Board software reads the OFF position as an active sensor. A sensor should be present for the corresponding sensor connector. Setting the DIP switch to ON disables the sensor position.
Refer to 508467-01 (Installation Instructions for Refrigerant Leak Detection Sensor Kit - Indoor Coils) to determine whether more than one (1) Refrigerant Detector Sensor is required.
Modes of Operation
The modes of operation for the RDS Non-Communicating Control Board are Initializing, Normal, Refrigerant Detected, Sensor Not Connected, and Fault.
Initializing
The RDS Non-Communicating Control Board is establishing connection with the refrigerant detection sensor and completing an initial five (5) minute purge sequence.
Normal
The HVAC system is functioning normally. The RDS Non-Communicating Control Board has not detected refrigerant.
Refrigerant Detected
When the RDS Non-Communicating Control Board detects refrigerant:
- The control board shuts off the (R) input (24VAC power) to the thermostat, de-energizing the outdoor unit compressor and heat sources (gas/electric strip heat). No heating or cooling demands will be met.
- The control board activates the blower (high speed). The blower purges refrigerant from the cabinet, plenum, and ductwork. After determining refrigerant levels are below the UL standard threshold, the blower continues for an additional seven (7) minutes.
- After the blower sequence, the HVAC system resumes normal operation.
The HVAC system may not maintain a cooling or heating setpoint if the RDS detects excessive R454B. Unaddressed refrigerant may cause the system to shut down on a low refrigerant pressure limit condition.
Sensor Not Connected
If no sensors are connected, the LED will flash red four (4) times, indicating a service fault (sensor communication issue). Heat/Cool operation is still permissible, and the blower motor runs continuously at high speed.
Fault
When a fault is detected, the indoor unit blower engages and remains engaged at a constant output until the fault is cleared.
Diagnostic Codes
The RDS Non-Communicating Control Board is equipped with a multicolor LED (Light-Emitting Diode) that signals its state. See Table 2 for diagnostic codes.
| State | LED Diagnostic Code | Action |
|---|---|---|
| Initializing | Flashing green¹ | Not Applicable |
| Monitoring | Solid green with blue flash² | Not Applicable |
| Mitigating (Refrigerant Detected) | Flashing blue | Check coil tubes for refrigerant. Repair the issue and restart the equipment. |
| Fault/Service | Solid blue, interrupted by issue flash code | Refer to Table 7 for troubleshooting steps. |
¹ A rapid flash indicates the RDS Non-Communicating Control Board is in the process of sensor enumeration.
² A blue flash indicates a purge has previously occurred.
Red LED Diagnostic Codes
Red diagnostic codes indicate a specific RDS Non-Communicating Control Board issue. Yellow diagnostic codes indicate the sensor's position (if applicable).
| Red Flash | Applies to Individual Sensor(s) | Issue | Action |
|---|---|---|---|
| 1 | Yes | Sensor indicates fault | Replace the sensor (Cat. # 26Z69) |
| 2 | No | Spare Code - Unused | Not Applicable |
| 3 | Yes | Incompatible sensor type | Replace with a compatible sensor (Cat. # 26Z69) • Verify sensor DIP switch settings are correct. • Verify sensor connection is secure. • Ensure connection is clean and free of debris. |
| 4 | Yes | Sensor communications issue | • Check wiring connections. • Ensure the indoor unit is wired to the "Blue INDOOR" terminal strip. • Verify the Room Thermostat is wired to the "Black TSTAT" terminal strip. |
| 5 | No | Indoor unit wiring connected incorrectly to the "Black TSTAT" terminal strip on the RDS Non-Communicating Control Board | • Check wiring connections. • Ensure the indoor unit is wired to the "Blue INDOOR" terminal strip. • Verify the Room Thermostat is wired to the "Black TSTAT" terminal strip. |
| 6 | No | Invalid configuration of sensor count | Verify the DIP switch setting is correct and matches the number of sensors being used. |
Test Button Functionality
The RDS Non-Communicating Control Board is equipped with a Test/Reset button. The Test button can be used to complete several functions, depending on the mode of operation.
| Mode of Operation | Press the Test Button to... |
|---|---|
| Normal | • Trigger a refrigerant detection response. • Verify all equipment is wired correctly into the RDS Non-Communicating Control Board (after installation). |
| Refrigerant Detected | Reset the RDS Non-Communicating Control Board to a normal mode of operation after refrigerant has been detected and purged from the HVAC system. |
| Fault | Reset the RDS Non-Communicating Control Board after troubleshooting and resolving a fault condition. If the fault is not resolved, the RDS Non-Communicating Control Board will enter the Fault mode again. |
Test Button - Additional Functions
Table 5 lists additional functions of the Test Button during different operational states.
| State | Press | Action |
|---|---|---|
| Initializing | Short | Skips remaining pre-purge after sensors are recognized by the RDS Non-Communicating Control Board. |
| Initializing | Long | Reset control. |
| Monitoring | Short | Clear purge-counter if prior mitigation has occurred; Test mitigation. |
| Monitoring | Long | Reset control. |
| Mitigating | Short | If testing mitigation, end test. |
| Servicing | Short | Reevaluate fault condition - if cleared, return to monitoring; otherwise, update indicator. |
| Servicing | Long | Reset control. |
| Fault | Short | Reevaluate fault condition - if cleared, return to monitoring; otherwise, update indicator. |
| Fault | Long | Reset control. |
Thermostat Compatibility
Thermostats that preserve memory settings are compatible with the RDS Non-Communicating Control Board. Examples include:
- Battery-powered thermostats
- Analog thermostats
- Smart thermostats
- Late-model programmable thermostats
Early-generation digital and programmable thermostats may not retain the operation mode and temperature setpoints after a power outage.
The following scenarios are likely to occur when home occupants are not available to adjust thermostat setpoints as the system recovers from refrigerant detection and resumes normal operation:
- Heating could be lost during a cold night.
- Cooling could be lost during a hot day.
- The thermostat could reset to an incorrect temperature setpoint.
Compatibility Verification
Complete the following process to determine thermostat compatibility:
- Change the thermostat's current setpoint and operating mode.
- Power cycle the breaker to the furnace.
- Note whether the thermostat maintained its setpoints and operating mode.
- If the thermostat maintained settings, it is compatible.
- If the thermostat did not maintain setpoint and/or operating mode, it is not compatible. Recommend replacing with a compatible thermostat.
Wait five (5) minutes before supplying power to the furnace breaker.
Additional Applications
In zoned applications, all dampers will remain open when the RDS Non-Communicating Control Board is in Fault or Refrigerant Detected mode. Normal heating and cooling demands are permissible, but the blower will remain engaged until the fault condition is addressed.
Zone HVAC System
If the RDS Non-Communicating Control Board is installed in a zone HVAC system, it will open all zone dampers if refrigerant is detected.
Proper wiring of the zone panel to the RDS Non-Communicating Control Board is required for all zone dampers to open.
After the purge sequence is complete, the zone system will resume normal operation.
External Alarm
(For applications with external alarms wired directly to the RDS Non-Communicating Control Board.)
The RDS Non-Communicating Control Board triggers the external alarm system when it enters Refrigerant Detected mode. For alarm notifications, it provides a dry relay contact rated 3A at 30 VAC/DC.
Start Up Test Procedure
The RDS Non-Communicating Control Board is equipped with a Test/Reset button (see "Test Button Functionality" on page 14). After mounting and wiring, restore power to the HVAC system. The system will run through a five (5) minute purge sequence. After the purge sequence, proceed to testing cooling and heating demand.
Cooling Demand
- Prompt a cooling demand at the thermostat.
- Press the Test button on the RDS Non-Communicating Control Board. The system executes a refrigerant detection response.
- Observe the sequence:
- The LED indicator flashes the sequence for refrigerant detection (flashing blue).
- The blower powers up.
- The outdoor compressor powers down.
- Press the Test button to terminate the simulated Refrigerant Detected mode upon test completion.
Heating Demand
- Prompt a heating demand at the thermostat.
- Press the Test button on the RDS Non-Communicating Control Board. The system executes a refrigerant detection response.
- Observe the sequence:
- The LED indicator flashes the sequence for refrigerant detection (flashing blue).
- The blower powers up.
- The gas burners power down.
- The outdoor compressor powers down.
- Press the Test button to terminate the simulated Refrigerant Detected mode upon test completion.
Installation is complete after both sequences are successfully completed.
Wiring Diagrams
Lennox provides wires for the sensor cable. Field-supplied wires are required for the RDS installation. The RDS supports OEM and non-OEM split gas furnace and air handler installations. Wiring diagrams are provided for common split furnace system configurations.
Two Stage Heat Pump with Two Stage Furnace Wiring Diagram
Diagram Description: Illustrates wiring between a Thermostat, the RDS Control Board (labeled "RDS Field Kit - 24 Volt Cat # (27A02)"), an RDS Sensor, a Two Stage Heat Pump, and a Two Stage Gas Furnace. It shows terminal connections for each component, including optional float switch wiring and terminal block designations (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit). Notes specify requirements for Dual Fuel applications.
Single Stage Heat Pump with Air Handler Wiring Diagram
Diagram Description: Shows wiring connections for a Single Stage Heat Pump system. It includes a Thermostat, the RDS Control Board, an RDS Sensor, and an Air Handler. Terminal blocks are designated (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit). Optional float switch wiring is also depicted.
Single Stage Outdoor Unit with Single Stage Furnace/Air Handler Wiring Diagram
Diagram Description: Depicts wiring for a Single Stage Outdoor Unit connected to a Single Stage Furnace/Air Handler. It shows connections from a Thermostat, the RDS Control Board, and the Outdoor Unit to the Indoor Unit. Terminal block designations are provided (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit), along with notes for Communicating Thermostat and Indoor Unit terminal blocks.
Single Stage Furnace/Air Handler with Variable Capacity Non-Communicating Outdoor Unit Wiring Diagram
Diagram Description: Illustrates wiring for a system with a Single Stage Furnace/Air Handler and a Variable Capacity Non-Communicating Outdoor Unit. It includes a Thermostat, the RDS Control Board, and the Variable Capacity Outdoor Unit. Terminal block designations are provided (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit). Notes indicate optional DS terminal wiring for De-Humidification Mode and the installation of a jumper between Y1 and Y2.
Two Stage Furnace/Air Handler with Variable Capacity Non-Communicating Outdoor Unit Wiring Diagram
Diagram Description: Shows wiring for a system with a Two Stage Furnace/Air Handler and a Variable Capacity Non-Communicating Outdoor Unit. It includes a Thermostat, the RDS Control Board, and the Variable Capacity Outdoor Unit. Terminal block designations are provided (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit). Notes mention optional DS terminal wiring for De-Humidification Mode and refer to indoor unit installation instructions for Two Stage unit configuration.
Non-Communicating Zoning with Single Stage Indoor Unit and Single Stage Outdoor Unit Wiring Diagram
Diagram Description: Depicts a zoning system with a Single Stage Indoor Unit and Single Stage Outdoor Unit. It shows connections from a Thermostat, the RDS Control Board, and the Outdoor Unit to a Zone Control Panel, which then controls multiple Dampers (Damper 1, Damper 2). Terminal block designations are provided (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit). A note specifies that for Non-Lennox Dampers, the relay must be wired as "Powered Open."
Non-Communicating Zoning (LZSV) with Variable Speed Indoor Unit and Two Stage Outdoor Unit Wiring Diagram
Diagram Description: Illustrates a zoning system (LZSV) with a Variable Speed Indoor Unit and a Two Stage Outdoor Unit. It shows multiple Thermostats (Zone 1-4), the LZSV Zoning System, the RDS Control Board, and the Variable Speed Indoor Unit. Connections are shown from a 24 Volt Transformer to the system. Terminal block designations are provided (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit). A note specifies that for Non-Lennox Dampers, the relay must be wired as "Powered Open."
Non-Communicating Zoning (LZSV) with Variable Speed Indoor Unit and Two Stage Heat Pump Wiring Diagram
Diagram Description: Depicts a zoning system (LZSV) with a Variable Speed Indoor Unit and a Two Stage Heat Pump. It shows multiple Thermostats (Zone 1-4), the LZSV Zoning System, the RDS Control Board, and the Variable Speed Indoor Unit. Connections are shown from a 24 Volt Transformer to the system. Terminal block designations are provided (BLACK for Thermostat/Outdoor Unit, BLUE for Indoor Unit). A Defrost Tempering Kit is also shown, with a note indicating its requirement for Dual Fuel Application. A note specifies that for Non-Lennox Dampers, the relay must be wired as "Powered Open."
Diagnostic Codes and Troubleshooting
| State | LED Diagnostic Code | Action Required |
|---|---|---|
| Initializing | Flashing green | None |
| Monitoring | Solid green. If a prior mitigation occurred, a blue flash interrupts the solid green LED. | None |
| Mitigating (Refrigerant Detected) | Flashing blue | Check coil tubes for refrigerant. Repair the issue and restart the equipment. |
| Fault/Service | Solid blue, interrupted by issue diagnostic code | Refer to Table 7 for troubleshooting steps. |
| Red Flash | Applies to Individual Sensor(s) | Issue | Action Required |
|---|---|---|---|
| 1 | Yes | Sensor indicates fault | Replace the sensor (See "Refrigerant Detection System Sensors" on page 8.) |
| 2 | No | Spare Code - Unused | Not Applicable |
| 3 | Yes | Incompatible sensor type | Replace the sensor (See "Refrigerant Detection System Sensors" on page 8.) • Verify sensor DIP switch settings are correct. • Verify sensor connection is secure. • Ensure connection is clean and free of debris. |
| 4 | Yes | Sensor communications issue | • Check wiring connections. • Ensure the indoor unit is wired to the "Blue INDOOR" terminal strip. • Verify the Room Thermostat is wired to the "Black TSTAT" terminal strip. |
| 5 | No | Indoor unit wiring incorrectly connected to the "Black TSTAT" terminal strip on the RDS control. | • Check wiring connections. • Ensure the indoor unit is wired to the "Blue INDOOR" terminal strip. • Verify the Room Thermostat is wired to the "Black TSTAT" terminal strip. |
| 6 | No | Invalid configuration of sensor count | Verify the DIP switch setting is correct and matches the number of sensors being used. |
