UNIT SENSORS
Sensors connect to the heat pump control through a
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
Page 33
XP17 SERIES
