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Is LED status light on?
Is LED status light blinking rapidly
without a pause?
Is LED status light blinking ON/OFF slowly
with a combination of short and long flashes?
Determine status code. The status code is a
2 digit number with the first digit determined
by the number of short flashes and the second
digit by the number of long flashes?
Go to section below for the status code that
was flashed.
Is there 115V at L1 and L2?
Is there 24V at SEC-1 and SEC-2?
Replace furnace control.
Check for correct line voltage polarity. If
units are twinned, check for proper low-
voltage (24V) transformer phasing.
To recall status code briefly remove and reconnect one RED wire from the
draft safeguard switch to display stored status code. On RED LED control do
not remove power or blower access panel before initiating status code recall.
You can also recall the previous status code by momentarily shorting the
TEST/TWIN terminal to Com24V terminal until the LED goes out. LED will
flash the status code of the previous fault or status code #11 (1 short and 1
long flash) if there was no previous fault. After the control repeats the code
4 times, the control will start the component test sequence. Once indicated
the control will turn ON at HI HEAT speed. The inducer will run for the entire
component test. The HSI, blower motor LO HEAT speed, HI HEAT speed, and
COOL speed will run for 10 – 15 seconds each. Gas valve and humidifier will
not be turned on. When the blower motor is turned OFF the inducer will be
switched to low-speed for 10 seconds.
Was there a previous status code other
than #11?
Is door switch closed?
Is there 115V going to switch?
Replace door switch.
Replace transformer.
Does the control respond to W/W1, W2, Y1,
Y/Y2, and G (24V) thermostat signals?
Run system through a low-heat, high-heat,
or cooling cycle to check operation. Status
codes are erased after 72 hours. On RED
LED boards stored status codes can also be
erased whenever (115V or 24V) is interrupted.
Replace furnace control.
Is door switch closed?
Is circuit breaker closed?
Check for continuity in wire from circuit
breaker to furnace.
Close circuit breaker and go back to START.
Check room thermostat or
interconnecting cable.
Is 24V present at W/W1, W2, Y1, Y/Y2 or G
thermostat terminals on the furnace control?
Disconnect all the thermostat wires from the
furnace control.
Does the problem repeat when using a
jumper wire?
The thermostat is not compatible with the
furnace control. Either install a ballast resistor,
connect the Com24V thermostat terminal to
the thermostat, or replace the thermostat.
NO
YES
YES
NO
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
YES
NO
NO
NO
YES
YES
NO
NO
START
NO
TROUBLESHOOTING GUIDE
A02107A
Fig. 62 -- Troubleshooting Guide 2-- Speed
312A