Auto-Zone Control Systems Auto-Zone Basic Systems Installation & Operation (Version 02C) - Manual (Page 122)

Section 4 Auto-Zone Basic
4-20 Start-Up and Troubleshooting
Zone Sensor reading incorrectly
• Is the sensor near a source of heat or a cold draft? Location is a common problem.
The sensor should be mounted on an inside wall away from heat sources and in a
location with adequate room air circulation.
• Is the voltage reading correct? Is the resistance reading correct? Check Table 4-2
in this section.
• Is wiring correct? Check for errors.
Check the Room Sensor
• To meter the Room Sensor:
With the sensor connected to the Zone Controller board, read the voltage on the
sensor terminals. If the voltage does not match the TEMPERATURE/
RESISTANCE chart, unplug the two-position room sensor terminal block. Using
your meter, check the resistance of the unplugged terminal block. Use the sup-
plied TEMPERATURE/RESISTANCE chart to see if the sensor is within a rea-
sonable range. Readings that are much too high or too low generally indicate wir-
ing problems.
• To meter the Slide Adjust (optional):
Unplug the four-position AUX terminal block. Use your ohmmeter to check the
resistance between the GND wire on the two-position room sensor terminal block
and the AUX1 terminal on the unplugged terminal block.
The resistance for various positions of the slider on the sensor should be as follows:
Full UP position 15K
Ω (± 500 Ω)
MID position 12.5K
Ω (± 500 Ω)
Full DN position 10K
Ω (± 500 Ω)