Thermostat User Manual

6-6 l
Troubleshooting
Shut Down Alarms (continued)
Problem
A3 Process Heater High
Temperature – The snap switch
in the process heater tube
opens due to excessive temper-
ature.
A10 RTD Integrity – If a
RTD is faulty.
A39 EEProm Write Error.
Possible cause
There is an air flow blockage or loose
hoses.
The isolation contactor failed in the
closed position.
The heater solid state relays (SSRs)
failed.
No air flow or the airflow is reversed.
The connection in the electrical enclo-
sure for the RTD is loose.
The connection of the RTD plug on the
control board is loose.
One of the RTDs has failed.
The RTD is enabled but wired incorrect-
ly.
Internal control board problem.
Solution
Remove the blockage.
Tighten any loose hoses.
Replace the isolation contactor.
Replace the failed heater solid state
relays (SSRs).
Turn on the blower.
Reverse the connection points of the
hoses.
Check the operation of the differential
pressure switch.
Check the RTD plug connection and
tighten if needed.
Check the plug connection and tighten if
needed.
Replace the RTD.
Move the wires to the proper terminals
(see the wiring diagrams supplied with
the unit).
Replace the control board.