Figure 8: Altitude Compensation in Meters Above Sea
Level
Troubleshooting
About this task:
The transmitter is not field repairable.
In the event the unit is not functioning properly, perform
the following to identify the symptoms and determine a
solution; verify that:
1. the unit is mounted properly and the appropriate
output jumper is selected
2. all wiring is correct
3. the power supply voltage level is 20 to 30 VAC or 18
to 30 VDC
Result
Note:
The diagnostic Light Emitting Diodes (LEDs)
shown in the lower right-hand corner of Figure 5
indicate operational status:
• V7 lights up if the self-diagnostics procedure detects an
abnormality.
• V10 pulses to indicate that the device is operational.
If the transmitter does not operate after completing these
steps, replace the unit.
Testing the Relay Module
About this task:
To confirm that the relay is operating correctly, perform
the following procedure:
Important:
To expose the sensing portion of the
probe, loosen the probe retention screw, and remove
the probe from the duct. After testing is complete,
reinstall the probe, and tighten the probe retention
screw.
1. Temporarily shut off power to the unit.
2. Temporarily remove wires connected to the relay
screw terminal.
3. Connect a multimeter to the relay terminals.
4. Read the resistance level to determine whether the
contacts are open or closed.
- If the contacts are closed, replace the unit with
the appropriate relay module, and restart this
procedure.
- If the contacts are open, apply power to the
transmitter.
5. Determine whether the contacts are open or closed.
- If the contacts are closed, the relay is
functioning properly, and no further testing is
necessary.
- If the contacts are open, increase the CO
2
concentration by exhaling near the probe,
looking for a change in the resistance value.
- If no change is noted, confirm that the CO
2
concentration has been raised above the trip
point.
- - Check the transmitter output signal
with a voltmeter to make sure the
signal has risen above the 1,000 ppm
relay trip point.
- - If the output signal has not
reached the trip point, it may be
necessary to further increase the CO
2
concentration.
- If the contacts are open after exceeding
the trip point, replace the unit with the
appropriate module, and restart this
procedure.
6. Disconnect power to the transmitter.
7. Disconnect the multimeter from the relay terminals.
8. Reconnect the wires to the relay screw terminal.
9. Reconnect power to the transmitter.
10. Reposition the cover.
Repair Information
If the CD-Pxx-00-0 Series Duct Mount CO
2
Transmitter fails
to operate within its specifications, replace the unit. For
a replacement transmitter, contact the nearest Johnson
Controls representative.
CD-Pxx-00-0 Series Duct Mount CO
2
Transmitter Installation Guide
4