Installation Guide

49
DIAGNOSTICS
Accessing the furnace’s diagnostics menu provides ready access to the last ten faults detected by the furnace. Faults are stored
most recent to least recent. Any consecutively repeated fault is stored a maximum of three times. Example: A clogged return air
filter causes the furnace limit to trip repeatedly. The control will only store this fault the first three consecutive times the fault
occurs.
NOTE: It is highly recommended that the fault history be cleared when performing maintenance or servicing the furnace.
NETWORK TROUBLESHOOTING
The indoor control is equipped with a bank of three DIP switches that provide biasing and termination functions for the commu-
nications transmission lines. The outdoor control in the communicating compatible unit is equipped with a bank of two DIP
switches that provide termination functions for the communications transmission lines. Communications errors will result if
these switches are not correctly set. Note that the ON position is the correct position for all bias and pull up/pull down DIP
switches.
The ComfortNet™ system is a fully communicating system, and thus, constitutes a network. Occasionally the need to troubleshoot
the network may arise. The furnace control board has some on-board tools that may be used to troubleshoot the network. These
tools are: red communications LED, green receive (Rx) LED, and learn button.
• Red communications LED – Indicates the status of the network. The table below indicates the LED status and the
corresponding potential problem.
• Green receive LED – Indicates network traffic. The table below indicates the LED status and the corresponding potential
problem.
• Learn button – Used to reset the network. Depress the button for approximately 2 seconds to reset the network.
SYSTEM TROUBLESHOOTING
NOTE: Refer to the instructions accompanying the ComfortNet compatible outdoor AC/HP unit for troubleshooting information.
Refer to the Troubleshooting Codes for a listing of possible furnace error codes, possible causes and corrective actions.
FAULT RECALL SEQUENCE
• Only allowed in standby mode while display is showing ON.
• Hold fault recall push-button for 2-5 seconds (until display is blank) and then release.
• Display will then be blank for 2 seconds before displaying faults stored in history.
• All faults are displayed one time, from most recent to least recent.
• A Maximum of 3 consecutive faults of the same type will be logged.
• Each error is displayed for 2 seconds, with a blank screen for 1 second in between.
• When all errors have been displayed, the display returns to ON.
LED LED Status Indication Possible Causes Corrective Action(s) Notes & Cautions
Off • Normal condition • None • None • None
• Control power up
• Learn button depressed
Rapid Flashing • Normal network traffic • Control is “talking” on
network as expected
• None • None
• Data 1 and data 2 wires reversed
at furnace, thermostat or
communicating compatible
outdoor AC/HP
•Check communications
wiring (data 1/ data 2
wires).
•Turn power OFF prior to
repair.
• Short between data 1 and
data 2 wires.
•Check wire connections at
terminal block
• Verify wires at terminal
blocks are securely twisted
together prior to inserting
into terminal block.
• Short between data 1 or
data 2 wires and R
(24VAC) or C (24VAC
common).
•Check data 1/ data 2
voltages.
•Verify data 1 and data
voltages as described above
Red
Communications
LED
2 Flashes • Out-of-box reset • None • None
Green
Receive
LED
On Solid • Data 1/ Data 2 miss-
wire