Lennox XC21 Series Unit Information page 33

COIL TEMPERATURE SENSOR
This model does not use a coil temperature sensor. The
cable assembly attached to the main control's E30
connection has a 10K resister installed between pins 5 and
6 as illustrated in figure 19.
Ambient Air
Temperature
Sensor
High Discharge Line
Temperature Sensor
Figure 19. 10k Resistor Location
TESTING AMBIENT (RT13) AND HIGH DISCHARGE
LINE TEMPERATURE (RT28) SENSORS
Sensors connect through a field-replaceable harness
Sensor Temperature Range °F (°C)
Outdoor
−40ºF to 140ºF (−40ºC to 60ºC)
(Ambient)
Discharge −35ºF to 310ºF (−37ºC to 154ºC)
Note: Sensor resistance decreases as sensed temperature increases (see tables 7 and 8.
E33 JUMPER (TEST) PINS
PLACING THE JUMPER ON THE E33 JUMPER PINS (SEE PAGE 26 FOR LOCATION OF E33 JUMPER PINS) ALLOWS THE TECHNICIAN TO
S
CLEAR COMPRESSOR ANTI−SHORT CYCLE DELAY.
S
CLEAR FIVE−STRIKE FAULT LOCKOUTS
S
SET THE UNIT CAPACITY CODE (PROCEDURE PROVIDED ON PAGE 41).
PLACE A JUMPER ON
ONE SECOND
JUMPER OFF POSITION.
CLEARS ANY SHORT CYCLE LOCKOUT AND FIVE STRIKE
FAULT LOCKOUT FUNCTION, IF APPLICABLE. NO OTHER
FUNCTIONS WILL BE EXECUTED AND UNIT WILL CONTINUE
IN THE MODE IT WAS OPERATING.
NOTES:
1 PLACING A JUMPER ON THE E33 PINS WILL NOT RESET (REBOOT) THE MAIN CONTROL (A175). THE ONLY WAY TO RESET THE OUTDOOR UNIT IS TO
CYCLE THE 24VAC POWER TO THE OUTDOOR UNIT'S MAIN CONTROL.
2 IF THE JUMPER REMAINS ON THE E33 PINS FOR LONGER THAN FIVE SECONDS, THE MAIN CONTROL WILL IGNORE THE JUMPER ON E33 PINS AND
REVERT TO NORMAL OPERATION.
10K resistor
Table 6. Sensor Temperature / Resistance Range
HIGH / LOW PRESSURE SWITCHES AND HIGH DISCHARGE TEMPERATURE SENSOR.
Y1 Active
1
THE E33 PINS FOR LONGER THAN
2
. THEN REMOVE JUMPER AND PLACE IN
Figure 20. Multi−Function E33 Jumper (Test) Pin
Page 33
assembly that plugs directly into the main control. Through
these sensors, the main control can monitor outdoor
ambient and discharge line temperature fault conditions.
As the detected temperature changes, the resistance
across the sensor changes. Tables 7 and 8 lists 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 6.
When a sensor indicates a resistance value that is not
within the range as listed in table 6, then the following
condition may be present:
S
Sensor detects an out−of−range outdoor ambient air
temperature condition and will display LED alert code
on the main control.
S
The sensor is operating normally when the ambient air
temperature at the sensor is below or above the main
control's expected ohm values. The main control will
indicate the sensor as faulty, however under this
scenario, the sensor is not actually faulty.
S
Once the outdoor ambient air temperature has
returned to within the sensor's normal operating range,
the LED alert code will automatically stop.
Resistance values range (ohms)
280,000 to 3750
41,000 to 103
FACTORY DEFAULT
JUMPER SETTING
Pins/ Wire
Color
3 and 4 (Black)
1 and 2 (Yellow)
JUMPER
JUMPER
OFF
ON
XC21