Lenox P506640-01 installation instructions Emergency Heat Amber Light, Defrost System Overview

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Defrost System

This section addresses:

SEmergency Heat

SDefrost System Overview

SDefrost Control Connections, Jumper Settings and Features

SOperational Mode Overview (Calibration, Normal and Defrost)

SDefrost Cycle Actuation

EMERGENCY HEAT (AMBER LIGHT)

An emergency heat function is designed into some room thermostats. This feature is applicable when isolation of the outdoor unit is required, or when auxiliary electric heat is staged by outdoor thermostats. When the room thermostat is placed in the emergency heat position, the outdoor unit control circuit is isolated from power and field-provided relays bypass the outdoor thermostats. An amber indicating light simultaneously comes on to remind the homeowner that he is operating in the emergency heat mode.

Emergency heat is usually used during an outdoor unit shutdown, but it should also be used following a power outage if power has been off for over an hour and the outdoor temperature is below 50°F (10°C). System should be left in the emergency heat mode at least six hours to allow the crankcase heater sufficient time to prevent compressor slugging.

DEFROST SYSTEM OVERVIEW

The control monitors ambient temperature, outdoor coil temperature, and total run time to determine when a defrost cycle is required. The coil temperature probe is designed with a spring clip to allow mounting to the outside coil tubing. The location of the coil sensor is important for proper defrost operation.

NOTE − The demand defrost control accurately measures the performance of the system as frost accumulates on the outdoor coil. This typically will translate into longer running time between defrost cycles as more frost accumulates on the outdoor coil before the demand defrost control initiates defrost cycles.

DEFROST CONTROL CONNECTIONS, JUMPERS SETTINGS AND FEATURES

Pressure Switch 5−Strike Lockout

The internal control logic of the demand defrost control counts the pressure switch trips only while the Y1 (Input) line is active. If a pressure switch opens and closes four times during a Y1 (Input), the control logic will reset the pressure switch trip counter to zero at the end of the Y1 (Input). If the pressure switch opens for a fifth time during the current Y1 (Input), the control will enter a lockout condition.

The 5−strike pressure switch lockout condition can be reset by cycling OFF the 24−volt power to the demand defrost control or by shorting the TEST pins between 1 to 2 seconds. All timer functions (run times) will also be reset.

If a pressure switch opens while the Y1 Out line is engaged, a 5−minute short cycle will occur after the switch closes.

Demand Defrost Control Pressure Switch

Connections

The unit’s automatic reset pressure switches (LO PS − S87 and HI PS − S4) are factory−wired into the demand defrost control on the LO−PS and HI−PS terminals, respectively.

Demand Defrost Control Sensors

Sensors connect to the demand defrost control through a field-replaceable harness assembly that plugs into the demand defrost control as illustrated in figure 1. Through the sensors, the demand defrost control detects outdoor ambient, coil, and discharge temperature fault conditions. As the detected temperature changes, the resistance across the sensor changes.

Testing Demand Defrost Control Sensors

Sensor resistance values can be checked by ohming across pins shown in table 11.

Table 11. Sensor Temperature /Resistance Range

 

 

 

Pins/W

 

Temperature

Resistance values

ire

Sensor

Range °F (°C)

range (ohms)

Color

 

 

 

 

Outdoor

−35 (−37) to 120 (48)

280,000 to 3750

3 & 4

 

 

 

(Black)

 

 

 

 

Coil

−35 (−37) to 120 (48)

280,000 to 3750

5 & 6

 

 

 

(Brown)

 

 

 

 

Discharge (if

24 (−4) to 350 (176)

41,000 to 103

1 & 2

applicable)

 

 

(Yellow)

 

 

 

 

Note: Sensor resistance increases as sensed temperature decreases.

Tables 12 and 13 shows how the resistance varies as the temperature changes for various types of sensors.

NOTE − When checking the ohms across a sensor, be aware that a sensor showing a resistance value that is not within the range shown in table 11, 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.

Defrost Temperature Termination Jumper

Settings (P1)

The demand defrost control selections are: 50, 70, 90, and 100°F (10, 21, 32 and 38°C). The shunt termination pin is factory set at 50°F (10°C). If temperature shunt is not installed, default termination temperature is 90°F (32°C).

Test Pins (P1) Function

Placing the jumper on the field test pins (P1) allows the technician to:

SClear short cycle lockout

SClear five−strike fault lockout

SCycle the unit in and out of defrost mode

SPlace the unit in defrost mode to clear the coil See figure 27 for flowchart of test pin (P1) operations.

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Contents Shipping and Packing List Table of ContentsGeneral Side View Unit Dimensions − inches mmModel Number Identification XP16−024 Base Section XP16 Base with LegsCaps and Fasteners Torque Requirements Typical Unit Parts ArrangementDetail a Using Manifold Gauge SET Operating Gauge Set and Service ValvesOperating Service Valves To Access Service Port Operating Ball−Type Service Valve3RECOVERING Refrigerant Recovering Refrigerant from Existing System1DISCONNECT Power Method Method 2 LimitationsNew Outdoor Unit Placement Detail a Outside Unit Placement Placement, Slab Mounting and Stabilizing UnitLouvered Panel Installation Removing and Installing PanelsLouvered Panel Removal Line Set Requirements NEW or Replacement Line SET InstallationUsing Existing Line SET Adding Polyol Ester OIL RequirementsRefrigerant Line SET From Vertical to Horizontal Refrigerant Line SET Alling Horizontal RunsBrazing Connections Brazing Procedures 1CUT and Debur6BRAZE Line SET Wrap Service ValvesFlow Nitrogen 7PREPARATION for Next Step2CONNECT Gauges and Equipment for Flushing Procedure Sensing Bulb Installation Installing New Indoor Metering DeviceIndoor Expansion Valve Installation Equalizer Line InstallationTest for Leaks Evacuating Line Set and Indoor Coil S S SElectrical Connections Size Circuit and Install Disconnect2INSTALL Thermostat 24VAC Transformer4HIGH Voltage Power Supply Connections LOW Voltage ConnectionsTypical Field Wiring Typical Unit Wiring Diagram −024, −036 and −048 Only Typical Unit Wiring Diagram −060 Only Unit Start−Up Unit START−UPConnect Manifold Gauge SET and Weigh in Charge Leak CHECK, Repair and EvacuateCalculating System Charge for Outdoor Unit Void of Charge Connections for Optimizing System Charge Indoor UnitAdjusting Indoor Airflow Optimizing ProcedureOptimizing System Refrigerant Charge LIQº SATºSCº = XP16−048−230 XP16−036−230XP16−060−230 Temperature Pressures Normal Operating PressuresSystem Operation Unit ComponentsTest DelayDS2 Green LED FAN TWO Connectors 24VACSlow Demand Defrost Control A108 Diagnostic LedsDS2 DS1 OFFSECOND−STAGE Operation Emergency Heat Amber Light Defrost Control CONNECTIONS, Jumpers Settings and FeaturesDefrost System Defrost System OverviewOperational Mode Overview Compressor Delay Mode P5Defrost Cycle Actuation Defrost Demand Mode Thirty 30 Minute TimeTemperature Mode TIME/TEMPERATURE Mode HOW did Defrost TERMINATE?Degrees Resistance Fahrenheit 136.3 2680 High Discharge Sensor RT28 Temperature / Resistance Range Test Pin P1 Functions S STwo−Stage Modulation Compressors Checks MaintenanceProcedure Tools RequiredHomeowner Outdoor Unit FAN Motor TemperatureCompressor PressuresXP16 Start−Up and Performance Cooling ModeStart UP Checks
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