Network Troubleshooting - Amana MVM97 Installation Instructions Manual

1 2 R
1 2 R
1 2 R
System Wiring using Four-Wires
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 con-
secutively 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 communications transmission lines. The outdoor
control in the communicating compatible unit is equipped
with a bank of two DIP switches that provide termina-
tion 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
CTKO* 1 & 2
C
Thermostat
ComfortNet Compatible Furnace
C
Integrated Control Module
ComfortNet Compatible AC/HP
C
Integrated Control Module
position for furnace control board bias and pull up/
pull down DIP switches. Communications is achieved by
the difference between two DC signals. The signals and
transmission lines are referred to as "data 1" and "data
2." Typically, the data 1 line is approximately 2.8 VDC and
the data 2 transmission line is approximately 2.2 VDC. The
voltage difference between data 1 and data 2 must be 0.6
VDC.
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 trou-
bleshoot the network. These tools are: red communica-
tions LED, green receive (Rx) LED, and learn button.
• Red communications LED – Indicates the status of the
network. The following table indicates the LED status
and the corresponding potential problem.
• Green receive LED – Indicates network traffic. The
table below indicates the LED status and the corre-
sponding potential problem.
• Learn button – Used to reset the network. Depress
the button for approximately 2 seconds to reset the
network.