Lennox International Inc Dave Lennox Signature Collection XP17 System HEAT PUMPS Unit Sensors

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UNIT SENSORS

Sensors connect to the heat pump control through a field-replaceable harness assembly that plugs into the control. Through the sensors, the heat pump control detects outdoor ambient and coil temperature fault conditions. As the detected temperature changes, the resistance across the sensor changes. table 13 shows how the resistance varies as the temperature changes for both type of sensors. Sensor resistance values can be checked by ohming across pins shown in table 12.

NOTE , be

aware that a sensor showing a resistance value that is not within the range shown in table 12, may be performing as designed. However, if a shorted or open circuit is detected, then the sensor may be faulty and the sensor harness will need to be replaced.

Ambient Temperature Sensor (RT13)

See table 12 for sensor range. If the ambient sensor is detected as being open, shorted or out of the temperature range of the sensor, the heat pump control will not perform demand defrost operation. The heat pump control will revert to time/temperature defrost operation and will display the appropriate alert code. Heating and cooling operation will be allowed in this fault condition.

Coil Temperature Sensor (RT21)

See table 12 for sensor range. If the defrost coil sensor is open, shorted or out of the temperature range of the sensor, the heat pump control will not perform demand or time/temperature defrost operation and will display the appropriate fault code. Heating and cooling operation will be allowed in this fault condition.

High Discharge Line Temperature Sensor

This model does not use a high discharge line temperature sensor. The cable assembly attached to the heat pump control’s E30 connection has a 10K resister installed between pins 1 and 2 as illustrated in figure 24. No alerts or alarms would be generated if resistor is damage.

COIL TEMPERATURE

 

SENSOR

 

AMBIENT AIR

10K RESISTOR

TEMPERATURE SENSOR

 

Figure 24. 10k Resistor Location

Table 12. Sensor Temperature / Resistance Range

Sensor

Temperature

Resistance values

Pins/Wire

Range °F (°C)

range (ohms)

Color

 

 

 

 

 

Outdoor

 

 

3 and 4

(Ambient)

−40 (−40) to 140

 

(Black)

 

280,000 to 3750

 

 

(60)

5 and 6

 

 

Coil

 

 

 

 

(Brown)

 

 

 

 

 

 

 

NOTE Sensor resistance decreases as sensed temperature

increases (see table 13).

 

 

 

 

 

 

W Input Fault or Miswire

In case of a W input fault or possible miswire, the system will function as listed in the sequence of operation in figure 30.

Shift Delay (E37)

The heat pump control has a field−selectable function to reduce occasional sounds that may occur while the unit is cycling in and out of the defrost mode. When a jumper is installed on the DELAY pins (E37), the compressor will be cycled off for 30 seconds going in and out of the defrost mode. Units are shipped with jumper installed on DELAY pins.

*30

 

SECOND DELAY

FACTORY DEFAULT OR WHEN

JUMPER IS MISSING

 

 

30

0 SECOND DELAY

0

Figure 25. Shift Delay Settings

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XP17 SERIES

Image 33
Contents Table of Contents GeneralHeat Pumps Side View Access View Unit Dimensions −− Inches mmModel Number Identification Base with Elongated LegsControl BOX Typical Unit Parts ArrangementUsing Manifold Gauge Set Operating Service ValvesShipping and Packing List Operating Ball Type Service Valve Operating Angle Type Service ValveTo Access Service Port Reinstall Stem Cap1DISCONNECT Power Recovering Refrigerant from Existing SystemRecovering Refrigerant 2CONNECT Manifold Gauge SETUnit Placement Placement, Slab Mounting and Stabilizing Unit Detail a Outside Unit PlacementRemoving and Installing Panels Stabilizing Unit on Uneven SurfacesRoof Mounting Louvered Panel Removal Louvered Panel InstallationDetail C Detail D Detail aRefrigerant Line SET New or Replacement Line SetRefrigerant Line SET Alling Horizontal Runs Refrigerant Line SET From Vertical to HorizontalBrazing Connections 2CAP and Core Removal 1PIPING Panel Removal and Preparing Line SETFlow Nitrogen Wrap Service ValvesBraze Line SET 7PREPARATION for Next StepFlushing Line Set and Indoor Coil Flushing Line Set and Indoor CoilIndoor Expansion Valve Installation Installing Indoor Expansion ValveSensing Bulb Installation Equalizer Line InstallationLeak Test Leak Test Line Set and Indoor CoilS S S S Evacuating Line Set and Indoor Coil2INSTALL Thermostat Size Circuit and Install DisconnectElectrical 24VAC Transformer3A. Route Control Wires Ting Route Control Wires Ting4ROUTE High Voltage and Ground Wires Typical XP17 Wiring Heat Pump Control AGE Heat Pump Control A175 Jumpers and TerminalsHeat Pump Control A175 Jumper and Terminal Descriptions Flat metal jumper Field Control WiringFurnace Control Servicing Units Delivered Void of Charge Connections for Testing and ChargingUnit Start−Up System RefrigerantHeating Mode Indoor Airflow Check Cooling Mode Indoor Airflow CheckAdding or Removing Refrigerant Airflowindoor CoilSubcooling Charging Method Using HFC−410A Weigh In MethodAir Handler / Coil Match ups and Targeted Subcooling Values Psig Operating and Temperature PressuresDefrost System System OperationsUnit Sensors Resistor Location Sensor Temperature / Resistance RangeYES Defrost Calibration Sequence of OperationsS S Test Pin E33 FunctionsOr below Low Pressure S87 Switch OperationHigh Pressure Switch S4 Sequence of Operation Input Fault or Miswire Degrees Resistance Fahrenheit 136.3 2680 DS11 and DS14 ATUS, Fault Lockout LED Codes System Status, Fault and Lockout LED CodesResetting Fault and Lockout LED Codes DS15 and DS13 Ault Lockout LED CodesModerate Device Alert Status225ºF 107ºC Lockout Vice removed or Clears after Troubleshooting Field Configuration and TestingFAN Motor B4 Test Procedure FAN Motor Control A177 OPERATION,Fan Motor Control Stage LED Indicator Codes Fan Motor Control Error/Fault LED CodesFan Motor Control RPM, LED Code and DC Voltage Output Fan Motor Control Flash and Pause DurationsTOP Grille Adjustment TOP Grille or FAN Motor Mount Adjustment for FAN ClearanceFAN Motor Position Adjustment Demand BeginsFAN Motor Control A177 PULSE−WIDTH Modulation PWM Testing for External Power to Fan Motor Control Start StripTerminal FinishSnow Guard Top Cover MaintenanceHomeowner SunSource Home Energy System Cooling Mode XP17 Start−Up and Performance ChecklistHeating Mode START−UP Checks