Zn520 Controllers - Trane VUV Installation, Operation And Maintenance Manual

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 45. Receiver resistance table for all models
Nominal zone
Zone or setpoint temperature output
temperature resistance
55°F (12.8°C)
60°F (15.6°C)
65°F (18.3°C)
70°F (21.1°C)
75°F (23.9°C)
80°F (26.7°C
85°F (29.4°C)
b. WDS only: Measure between the grounded GND-
SIGNAL (black) wire and the FAN/SYSTEM (green)
wire. Compare resistance measurements to those
given in Table 46, p.

ZN520 Controllers

LED Activity
Green Status LED The green LED normally indicates whether
the controller is powered on (24 Vac supplied). Refer to
Table 47, p. 103.
Table 47. Green status LED activity for Tracer® ZN520
controllers
Green LED Activity
On continuously
Blinks (one blink)
Blinks (two blinks)
LED blinks (1/4 second on, 1/4 second,
off for 10 seconds)
LED off
(a) The Wink feature allows you to identify a controller. By sending a request from
the Rover service tool, you can request the controller to wink (blink on and off as
a notification that the controller received the signal). The green LED blinks (1/4
second on, 1/4 second off for 10 seconds) during Wink mode.
UV-SVX005G-EN
Table 45, p. 103.
Nominal setpoint/
heating setpoint
output resistance
17.47 kΩ 792 Ω
695 Ω
15.3 kΩ
597 Ω
13.49 kΩ
11.9 kΩ 500 Ω
403 Ω
10.5 kΩ
305 Ω
9.3 kΩ
8.25 kΩ 208 Ω
103.
Description
Power on (normal operation).
The controller is in manual output test
mode.
No diagnostics present.
The controller is in manual output test
mode.
One or more diagnostics are present.
(a)
Wink mode.
Power is off.
Controller failure.
Test button is pressed.
Diagnostics and Troubleshooting
Note: The output circuits are not electrically
powered; consequently, resistance can be
measured without risk of damage to the volt-
ohm meter.
Table 46. Receiver resistance table for model WDS
Fan command
High
Med
Low
Auto
Off
Cleaning the Sensor
NOTICE
Sensor Damage!
Spraying glass cleaner or any other solution directly on
the sensor may damage it.
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.
Yellow Comm LED The yellow comm LED blinks at the rate
the controller receives communication. The yellow LED does
not blink when the controller is transmitting communication
data. Refer to Table 48, p.
Table 48. Yellow comm LED activity for Tracer® ZN520
controllers
LED Activity Description
The controller is not detecting any communication.
Off continuously
(Normal for standalone applications.)
The controller detects communication. (Normal for
LED blinks or flickers communicating applications, including data
sharing.)
Abnormal condition or extremely high traffic on the
LED on continuously
link. High traffic on the link.
Nominal output resistance
16,130 Ω
13,320 Ω
10,770 Ω
2320 Ω
4870 Ω
103.
103