Diagnostics and Troubleshooting
78
UNT-SVX041D-EN
Measuring Output Resistance
To measure the resistance of receiver outputs for zone
temperature and setpoints for all models, and heating
setpoint and fan/system for the WDS:
1. Ensure that the GND-SIGNAL (black) wire and the
GND-POWER (yellow) wire are grounded to the
transformer.
2. Disconnect the ZONE (white) and SETPOINT (RED)
wires from the controller. Disconnect the HEAT
SETPOINT (brown) and FAN/SYSTEM (green) wires
from the controller, if applicable.
3. Measure resistance as follows:
a. All models: Measure between the grounded GND-
SIGNAL (black) wire and either the SETPOINT (red)
or ZONE (white) wire. Compare resistance
measurements to those in table below.
b. WDS only: Measure between the grounded GND-
SIGNAL (black) wire and the FAN/SYSTEM (green)
wire. Compare resistance measurements to those
given in the table below.
Note:
The output circuits are not electrically
powered; consequently, resistance can be
measured without risk of damage to the
volt-ohm meter.
Cleaning the Sensor
You can clean the sensor by applying glass cleaner to a
soft, non-abrasive cloth, and gently wiping the face,
including the buttons and LCD display. Use of a pre-
moistened towelette designed for lens or screen cleaning
is also acceptable.
Avoid inadvertent pressing of the Occupied/Unoccupied
buttons on the keypad on the WDS sensor as this may
result in an unwanted timed override or settings change.
Table 39. Receiver resistance table for all models
Zone or setpoint
temperature
Nominal zone
temperature
output resistance
Nominal setpoint/
heating setpoint
output resistance
55°F (12.8°C)
17.47 k
792
60°F (15.6°C)
15.3 k
695
65°F (18.3°C)
13.49 k
597
70°F (21.1°C)
11.9 k
500
75°F (23.9°C)
10.5 k
403
80°F (26.7°C
9.3 k
305
85°F (29.4°C)
8.25 k
208
Table 40. Receiver resistance table for model WDS
Fan command
Nominal output resistance
High
16,130
Med
13,320
Low
10,770
Auto
2320
Off
4870
NOTICE
Sensor Damage!
Do not spray glass cleaner or any other solution directly
on the sensor as it could damage it.
