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14 RED FLASHES: If the secondary voltage drops below
approximately 19 VAC, the control continues to energize
any relays that are already energized, but does not
energize any additional relays until the voltage level
increases.
15 RED FLASHES: If the secondary voltage drops below
approximately 16 VAC, the control immediately de-
energizes the relay outputs and does not energize
any relays until the voltage level increases above
approximately 20 VAC.
4 AMBER FLASHES: The control is receiving a Y signal
from the thermostat without a G signal. The furnace
operates normally in both heating and cooling, but this
status code is displayed in order to alert the user that
there is a wiring problem. Verify that the G wire from the
thermostat is connected correctly.
SOFT LOCKOUT: This control includes a soft lockout that
resets automatically after 1 h. This provides protection to
an unoccupied structure if a temporary condition exists
causing a furnace malfunction. An example of this is a
temporary interruption in gas supply that would prevent
the furnace from lighting. The control keeps trying to
light each hour and resumes normal operation if the gas
supply is restored.
HARD LOCKOUT: Some fault conditions result in a hard
lockout, which requires power to the control to be turned
off and then back on to reset the control. The control does
not automatically restart.
IGNITION CONTROL FLAME SENSE LEVELS
Normal flame sense current is
approximately 3.7 microamps DC (μa)
Low flame signal warning starts at 1.5 microamps.
Low flame signal control lockout point is
0.1 microamps DC (μa)
Installation Manual: RL18 Single-Stage Standard ECM Residential Gas Furnaces (Non-condensing Multi-position Standard
Diagnostic fault code storage and
retrieval
The control in this furnace is equipped with memory that
stores up to five error codes to allow a service technician
to diagnose problems more easily. This memory is
retained even if power to the furnace is lost. This feature
must only be used by a qualified service technician.
If more than five error codes have occurred, only the five
most recent are retained. The furnace control board has
a button, labeled LAST ERROR, that is used to retrieve
error codes. This function only works if there are no
active thermostat signals. Any call for heating, cooling, or
continuous fan must be terminated before attempting to
retrieve error codes.
To retrieve the error codes, push and release LAST ERROR
button. The LED on the control then flashes the error
codes that are in memory, starting with the most recent.
There is a 2 s pause between each flash code. After the
error codes have all been displayed, the LED resumes the
normal slow green flash after a 5 s pause. To repeat the
series of error codes, push the button again.
If there are no error codes in memory, the LED flashes
two green flashes. To clear the memory, push the LAST
ERROR button and hold it for more than 5 s. The LED
flashes three green flashes when the memory has been
cleared, then resumes the normal slow green flash after a
5 s pause.
Johnson Controls Ducted Systems
37
Low NOx)
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