AD-1252 Thermal Dispersion Probe Airflow Measuring System Installation Instructions
21
The LCD screen indicates a large
negative FPM and then cycles to a
large positive FPM value (applies to
older metal boxes only).
Multiple probes are trying to
communicate with the electronic
controller at the same time.
The probes are not communicating with
the transmitter.
Cycle power to the control transmitter.
Check the flashing lights. Only one
yellow light should flash at a time and
the lights must flash in sequence.
If the transmitter box is metal, remove
the bottom end plate and wrap electrical
tape across the bottom. Replace the
end plate so that it is insulated from the
RJ45 connector.
The RJ45 connector is shorting to the
bottom cover.
1. Remove the bottom cover of the
electronic controller.
2. Apply electrical tape around the
RJ45 connector.
The LCD screen goes blank or the
electronic controller communicates
with one probe and ignores the
others.
The transformer VA rating is too low.
Replace the existing transformer with a
transformer with the proper VA rating.
We recommend a dedicated
transformer for each air measurement
station.
•
4 probes with 4 sensors each -
65 VA minimum
•
3 probes with 4 sensors each -
48 VA minimum
•
2 probes with 4 sensors each -
35 VA minimum
•
1 probe with 4 sensors - 17 VA
minimum
Maximum VA is seen when there is no
flow or a very low flow. As flow
increases, VA decreases.
The output data varies and is not
consistent.
The dampers are not sequenced
properly.
Correct the sequence of operation.
The transmitter locks up, and
resetting the transmitter starts the
operation.
RF interference from local high output
transmitters (ambulance/police) is at
fault.
Shorten the CAT5e communications
cable and if it is not shielded, use
shielded cable or place in a conduit.
Minimize any cable loops or coils.
Erratic readings appear on the LCD.
Interference is at fault.
Ground the shield of the RJ45 probe
connectors at the bottom of the control
transmitter to the (-) 4 to 20 mA
temperature terminal at the top of the
control transmitter box. This solution
applies to units built prior to February
2011. In extreme cases, it may be
necessary to mount the control
transmitter in a grounded steel
enclosure.
Readings displayed are incorrect;
the mA output does not match the
LCD display.
Firmware version 8.2 does not display
values greater than 32,000 CFM.
Change the display to FPM or update
the firmware to version 8.3 or greater.
Degrees Fahrenheit is in lowercase
letters (degrees fahrenheit) on the
LCD screen.
A sensor error is at fault.
Cycle through sensors to determine
which sensor is not communicating.
Every green LED light is on and only
one or two probes are connected.
The LCD screen operates with no
probes connected.
When probes are connected, the
LCD screen is blank.
Bad capacitors (C1 and C2) are at fault.
Return the transmitter for repair.
Table 7: AD-1252 System Troubleshooting (Part 3 of 3)
Problem
Possible Cause
Corrective Action
