7
MANUAL FAN ON MODE
If the thermostat fan switch is moved to the ON position, the
circulator fan (low heat speed) and the electronic air cleaner
(optional) are energized. When the fan switch is returned to
the AUTO position, the circulator and electronic air cleaner are
de-energized.
TWINNING INTERFACE
The 50M58 is equipped with a single wire twinning interface.
If twinning is used, either control will process a call for heat,
cool or fan as described previously. However, after the heat- or
cool-on delay time expires, both units will energize the circulator
blowers at the same time. Likewise, after the heat- or cool-off
delay time expires, both units will de-energize the circulator at
the same time. This allows for the proper air flow to be obtained.
In a twinned application, the controls are able to communicate
no matter how the transformers are phased.
To enable twinning, connect the TWIN screw terminals on the
50M58 controls of the furnaces to be twinned to each other
using a single wire (14-22 AWG).
SYSTEM LOCKOUT AND DIAGNOSTIC FEATURES
SYSTEM LOCKOUT
When system lockout occurs, the gas valve is de-energized and
the low speed inducer blower and the low heat speed circula-
tor are energized. The electronic air cleaner (optional) will also
energize at this time. The diagnostic indicator light will flash to
indicate the system status.
To reset the control after system lockout,
do one of the
following:
1. Interrupt the call for heat at the thermostat for at least one
second but less than 20 seconds (if flame is sensed with
the gas valve de-energized, interrupting the call for heat at
the thermostat will not reset the control).
2. Interrupt the 24 VAC power at the control for at least 20
seconds. You may also need to reset the flame rollout sensor
switch.
3. After one hour in lockout, the control will automatically reset
itself.
LAST FAULT MODE
To retrieve fault codes, push and release the "LAST ERROR"
button for more than 1/5 second and less than 5 seconds. (Control
will indicate this period by solid GREEN for 1/5 to 5 seconds).
The LED will flash up to five stored fault codes, beginning with
the most recent. If there are no fault codes in memory, the LED
will flash two green flashes. The control will flash the most re-
cent error first and the oldest error last (last in first out). There
shall be 2 seconds between codes. Solid LED error codes will
not be displayed.
FAULT CODE RESET
To clear the fault code memory, push and hold the "LAST ER-
ROR" button for more than 5 seconds and less than 10 seconds.
(Control will indicate this period by RAPID GREEN FLASH for 5
seconds to 10 seconds.) The LED will flash three green flashes
when the memory has been cleared.
DIAGNOSTIC FEATURES
The 50M58 control continuously monitors its own operation and
the operation of the system. If a failure occurs, the red LED on the
control will flash a failure code.
If the failure is internal to the
control, the light will stay on. In this case, the entire control
should be replaced, as the control is not field-repairable.
If the sensed failure is in the system (external to control), the
LED will flash in the following flash-pause sequences to indicate
failure status (each flash will last approximately 0.25 seconds,
and each pause will last approximately 2 seconds.)
During a second-stage error condition, the red LED when in
lockout will flash groups of double pulses. The red LED will flash
on for approximately 1/15 second then off for 1/15 second then
on for 1/15 second, then off for 3/10 second. The pause between
groups of flashes is approximately 2 seconds.
The diagnostics will indicate the specific fault through the
following codes:
COOL MODE
In a typical system, a call for cool is initiated by closing the ther-
mostat contacts Y or YLO and G. The circulator motor speed is
selected by Dip Switch S2 (refer to option switch S2 positions
table on page 6) for the thermostat input that is energized. Once
the control receives a call for cool, a 5 second cool on delay
time is activated. This allows the compressor to energize prior
to the indoor circulator being energized. After the thermostat is
satisfied, the compressor is de-energized and the control starts
a 45 second circulator off delay. After the cool off delay period
expired the indoor circulator is de-energized.
If a call for cool (YLO or Y) is received without a G input the
control will energize the indoor circulator motor as per DIP
switch 2 setting but will display an Amber 4 flash to alert that
the thermostat G input is not present.
OPERATION
