GSX14 Service Manual

SERVICING
130
3. Provide a thermostat demand for low stage auxiliary heat
(W1). Measure the voltage between circuits 1 and 3 at
the on-board electric heat connector. Voltage should
measure 24VAC. Replace control if no voltage is
present.
NOTE: Allow for any built-in time delays before making
voltage measurements. Any electric heater faults that are
present may prevent the heater output from energizing.
Verify that no heater faults are present before making
voltage measurements.
4. Provide a thermostat demand for high stage auxiliary
heat (W1 + W2). Measure the voltage between circuits
1 and 3 at the on-board electric heat connector. Mea-
sure the voltage between circuits 2 and 3 at the on-board
electric heat connector. Voltage should measure 24VAC.
Replace control if no voltage is present.
Communications (Applies only to Systems with Compat-
ible ComfortNet
TM
Outdoor Unit and CTK0*Thermostat)
The integrated air handler control 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. These are described below
a. Red communications LED – Indicates the status of the
network. Refer to the Network Troubleshooting Chart for
the LED status and the corresponding potential problem.
b. Green receive LED – Indicates network traffic. Refer to
the Network Troubleshooting Chart for the LED status
and the corresponding potential problem.
c. Learn button – Used to reset the network. Depress the
button for approximately 2 seconds to reset the network.
Voltages between the two data lines and between each data
line and common may be used to determine if the network
is operating properly.
Do the following to measure the voltages on the communi-
cations data lines.
WARNING
Line Voltage now present.
1. With power on to the unit, measure voltage between
terminal "1" and terminal "C" on control board's ther-
mostat connector. Voltage should be as noted in the
table below.
2. Measure voltage between terminals "2" and "C".
3. Measure voltage between terminals "1" and "2".
4. If voltages are different than stated in the table below,
check thermostat wiring for opens/shorts. Confirm
that the BIAS and TERM dipswitches are in the ON
position.
5. The network troubleshooting chart on the next page
provides additonal communications troubleshooting
information.
Terminals
Nonimal dc
Voltages
1 to C > 2.5 Vdc
2 to C < 2.5 Vdc
1 to 2 > 0.2 Vdc