White Rodgers 1F85-277 Guía para resolver problemas descargar pdf (Pagina 58)

INTEGRATED

FURNACE CONTROLS

21M51U-843

OPERATION

TWINNING INTERFACE

The 50M51 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

50M51 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 sen-

sor 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 recent 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 50M51 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 fol-

lowing codes:

COOL MODE

In a typical single stage cooling system (Y connection), a call for

cool is initiated by closing the thermostat contacts. This energizes

the compressor and the electronic air cleaner (optional).

The circulator will be energized at cool speed after the COOL

delay-to-fan-on period. After the thermostat is satisﬁed, the

compressor is de-energized and the COOL delay-to-fan-off

period begins. After the COOL delay-to-fan-off period ends, the

circulator and the electronic air cleaner are de-energized.

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.

TECHNICAL HELP

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