White Rodgers Furnace 21D83M 843 User Manual

21D83M-843  
Integrated Single Stage  
Furnace Control Replacement Kit  
INSTALLATION INSTRUCTIONS  
FAILURETO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE  
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL  
INJURY AND/OR PROPERTY DAMAGE.  
DESCRIPTION  
The 21D83M-843 kit will replace the following Controls:  
Kit includes:  
1 – 50A66-843 ignition control board  
1 – Wiring harness (9-pin to 12-pin)  
1 – Wiring harness (4-pin to 6-pin)  
1 – Mounting panel  
4 – Stand-off fasteners  
1 – Circuit breaker  
Lennox  
White-Rodgers Page  
Reference  
10M9301 32M8801 50A65-120  
3
4
5
PROCEDURE 1  
Figure 1, Picture  
1, Table 1, Wiring  
Diagram 5001-6973  
12L6901  
56L8401 50A65-121  
24L8501  
63K8901  
97L4801  
50A62-120  
50A62-121  
50A62-820  
PROCEDURE 2  
Figure 1, Picture  
2, Table 2, Wiring  
Diagram 5001-6972  
1 – 4" blue wire  
2 – Wiring diagrams  
The kit includes the 50A66-843 which is an automatic gas  
interruptedignitioncontrolthatemploysamicroprocessor  
to continually monitor, analyze, and control the proper  
operation of the gas burner, inducer, and fan.  
100925-01 30W2501 21D83M-843  
100925-03 69M0801 50A66-122  
17W9201 69M1501 50A66-123  
23W5101 83M00  
PROCEDURE 3  
Thesecontrolsincorporatesystemfaultanalysisforquick  
gas flow shut-off, coupled with automatic ignition retry  
upon sensing a fault correction.  
Follow instructions for replacement of your model num-  
ber under the heading INSTALLATION.  
PRECAUTIONS  
Installation should be done by a qualified heating and air  
conditioning contractor or licensed electrician.  
If in doubt about whether your wiring is millivolt, line, or  
low voltage, have it inspected by a qualified heating and  
air conditioning contractor or licensed electrician.  
Do not exceed the specification ratings.  
WARNING  
Failure to comply with the following warnings  
couldresultinpersonalinjuryorpropertydamage.  
FIRE HAZARD  
• Do not exceed the specified voltage.  
• Replace existing control with exact model  
and dash number.  
• Protect the control from direct contact with  
water (dripping, spraying, rain, etc.).  
• If the control has been in direct contact with  
water, replace the control.  
• Label all wires before disconnection when  
servicing controls. Wiring errors can cause  
improper and dangerous operation.  
• Route and secure wiring away from flame.  
SHOCK HAZARD  
• Disconnect electric power before servicing.  
• Ensure proper earth grounding of appliance.  
!
All wiring must conform to local and national electrical  
codes and ordinances.  
This control is a precision instrument, and should be  
handled carefully. Rough handling or distorting compo-  
nents could cause the control to malfunction.  
Followinginstallationorreplacement,followmanufacturer’s  
recommended installation/service instructions to ensure  
proper operation.  
CAUTION  
!
Donotshortoutterminalsongasvalveorprimary  
control. Short or incorrect wiring may damage  
the thermostat.  
• Ensure proper connection of line neutral and  
line hot wires.  
EXPLOSION HAZARD  
• Shut off main gas to appliance until installa-  
tion is complete.  
PART NO. 37-7337B  
Replaces 37-7337A  
1244  
 
INSTALLATION  
PROCEDURE 1  
WARNING  
!
FIRE HAZARD  
REPLACING 10M9301, 12L6901, 32M8801,  
50A65-120, 50A65-121 or 56L8401  
• Do not exceed the specified voltage.  
• Replace existing control with exact model and  
dash number.  
• Protect the control from direct contact with water  
(dripping, spraying, rain, etc.).  
Mounting panel  
• If the control has been in direct contact with water,  
replace the control.  
• Label all wires before disconnection when servic-  
ingcontrols.Wiringerrorscancauseimproperand  
dangerous operation.  
Circuit breaker  
in series between  
Pin 3 and  
• Route and secure wiring away from flame.  
Transformer (TH)  
SHOCK HAZARD  
• Disconnect electric power before servicing.  
• Ensure proper earth grounding of appliance.  
• Ensure proper connection of line neutral and line  
Optional 4" blue  
wire to connect to  
Transformer (TH)  
hot wires.  
EXPLOSION HAZARD  
• Shut off main gas to appliance until installation is  
complete.  
Photo 1  
1. Disconnect all electrical power and shut off the gas  
supply to the furnace.  
2. Remove the access panel.  
3. Disconnect wiring and remove existing ignition  
control board from the control box.  
4. Install provided circuit breaker in unit control box  
or secure circuit breaker to a wire harness using  
wire ties.  
CAUTION  
Do not short out terminals on gas valve or primary  
control. Short or incorrect wiring may damage the  
thermostat.  
!
MOUNTING PANEL  
5. Position the provided mounting panel with the  
arrow on the front of the panel pointing up. Position  
the replacement 50A66-843 ignition control board  
over the holes marked "A" in figure 1. Insert the  
replacement control stand-off fasteners into the  
holes in the mounting panel.  
TheMountingPanelisrequiredinProcedure1andProce-  
dure 2.It will become part of the installation for Procedure  
1. It will be used as a template for locations to drill holes  
in Procedure 2, Step 4A and 4B. It will become part of  
the installation in Procedure 2, Step 4C.  
6. Insert the four provided stand-off fasteners into the  
back of the mounting panel in the holes marked "B"  
in figure 1. Insert the replacement control board  
assembly into the existing holes in the control box  
or blower panel.  
7. Insert provided circuit breaker in series between the  
blue transformer wire connecting position 3 on the  
12-pin connector to the transformer (TH), optional 4"  
blue wire provided for transformers that have a quick-  
connect terminal.  
B
A
B
A
C
C
Arrow on  
front of panel  
8. Connect the remaining 120 VAC hot and neutral wires  
and the flame sense wire to the replacement control  
per table 1, page 4.  
9. Affix wiring diagram 5001-6973 adjacent to the  
existing unit wiring diagram.  
B
B
C
C
A
A
10. Replace the access panel.  
Figure 1 – Mounting Panel  
11. Restore the electrical power and gas supply. Refer  
to the furnace installation instructions for start-up  
and check-out procedures.  
3
 
INSTALLATION  
over the marks. Use the mounting panel  
as a template to drill 3/16" holes through  
each of the holes marked "A". Install the  
replacement control in the freshly drilled holes  
inthebloweraccesspanel.Usealuminumtape  
to seal the unused holes.  
TABLE 1  
Type  
Existing  
Replacement  
Control Board  
COOL  
Control Board  
COOL-H  
HEAT-H  
PARK (2)  
EAC-H  
HEAT  
PARK (2)  
EAC  
LINE  
XFMR  
B. When replacing original 63K8901 board in  
downflow applications – Look at the existing  
control board holes as if the unit were installed  
in the upflow position. Make a mark 5/8"  
ABOVE each of the existing mounting holes.  
Position the provided mounting panel so that  
the holes marked "C" in figure 1, page 3 are  
over the marks. Use the mounting panel as a  
template to drill 3/16" holes through each of  
the holes marked "A". Install the replacement  
control in the freshly drilled holes in the blower  
access panel. Use aluminum tape to seal the  
unused holes.  
C. All other units – Position the provided  
mounting panel so that the arrow on the  
front of the panel is pointing up. Position the  
replacement 50A66-843 ignition control board  
over the holes marked "A" in figure 1, page 3.  
Insert the replacement control stand-off  
fasteners into the holes in the mounting panel.  
80UHG, 90UGF, G23, G26, GHR26, G32,  
GHR32, G40, G41, G50, G51, G60 and G61  
units – Insert the four provided stand-off  
fasteners into the back of the mounting panel in  
the holes marked "B" in figure 1. 80MGF, G24M  
and G27M units – Insert the four provided  
stand-off fasteners into the back of the mounting  
panel into the holes marked "C" in figure 1.  
Insert the replacement control board assembly  
into the existing holes in the control box or  
blower panel.  
L1  
120 VAC  
LINE-H  
XFMR-H  
HUM-H  
NONE  
LINE-N  
HUM-N  
EAC-N  
XFMR-N  
CIR-N  
E33  
HUM  
FAN  
Neutral  
120 VAC  
(5)  
Neutral  
120 VAC  
Flame Sense  
FS  
PROCEDURE 2  
REPLACING 24L8501, 50A62-120, 50A62-121,  
50A62-820, 56L8301, 63K8901 or 97L4801  
Mounting panel  
Wiring harness  
(4-pin to 6-pin)  
GND  
Transformer  
Circuit breaker  
in series between  
5. Insert provided circuit breaker in series between  
the blue wire on Pin 3 of the wiring harness (9-pin  
to 12-pin) and the blue transformer wire. Optional  
4" blue wire provided for transformers that have a  
quick-connect terminal.  
Wiring harness  
Pin 3 and Trans-  
(9-pin to 12-pin)  
former (TH)  
Optional 4" blue  
wire to connect to  
Transformer (TH)  
6. Connect the provided 9-pin to 12-pin wiring  
harness to the unit 9-pin connector.  
Photo 2  
7. Connect the provided 4-pin to 6-pin wiring harness  
to the unit 6-pin connector.  
1. Disconnect all electrical power and shut off the gas  
supply to the furnace.  
8. Connect the yellow wire from position 6 on the 12-  
pin connector to the yellow transformer wire.  
9. Connect GND wire to equipment ground.  
10. Connect the remaining 120 VAC hot and neutral  
wires and the flame sense wire to the replacement  
control per table 2, page 5 .  
11. Affix wiring diagram 5001-6972 adjacent to the  
existing unit wiring diagram  
12. Replace the access panel.  
2. Remove the access panel.  
3. Disconnect wiring and remove existing ignition  
control board from the control box.  
4. A. When replacing original 63K8901 board  
in upflow or horizontal applications or  
downflow applications – Look at the existing  
control board holes as if the unit were installed  
in the upflow position. Make a mark 1" to the  
right of each of the existing mounting holes.  
Position the provided mounting panel so that  
13. Restore the electrical power and gas supply. Refer  
to the furnace installation instructions for start-up  
and check-out procedures.  
the holes marked "C" in figure 1, page 3 are  
4
 
INSTALLATION  
PROCEDURE 3  
TABLE 2  
Type  
Existing  
Control Board  
Replacement  
Control Board  
REPLACING 100925-01, 100925-02,  
ACB COOL  
ACB HEAT  
PARK M1  
PARK M2  
ACC  
COOL  
HEAT  
PARK  
PARK  
EAC  
100925-03, 17W9201, 23W5101,  
30W2501, 50A66-122, 50A66-123,  
69M0801 or 69M1501  
1. Disconnect all electric power and shut off gas  
supply to the furnace.  
2. Remove the access panel  
3. Disconnect wiring and remove existing ignition  
control board.  
4. Insert the replacement board into existing holes.  
5. Reconnect wiring.  
L1  
120 VAC  
120 VAC HOT  
120 VAC TX  
HTG ACC  
ACB LOW  
LINE  
XFMR  
HUM  
FAN  
Neutral  
120 VAC  
Neutral 120 VAC  
Return (5)  
Neutral  
120 VAC (5)  
6. Replace access panel.  
Flame Sense  
E33  
FS  
7. Restore the electrical power and gas supply. Refer  
to the furnace installation instructions for start-up  
and check-out procedures.  
OPERATION  
goes into retry mode. For the second attempt to ignite  
gas within the same call for heat, the control increases  
the ignitor temperature to the value it was on the third  
previous successful ignition. After ignition is successful,  
the control sets the ignition temperature at this value for  
the next 255 calls for heat, after which the control repeats  
the adaptive algorithm. The control is constantly making  
adjustments to the ignitor temperature to compensate for  
changes in the line voltage.  
OPTION SWITCHES  
The option switches on the 50A66-843 control are used  
to determine the length of the heat delay-to-fan-off and  
cool-delay-to-fan-off periods. The following table shows  
the time periods that will result from the various switch  
positions.  
OPTION SWITCH POSITIONS  
HEAT delay-  
to-fan-off:  
Set switch  
The 80 VAC Silicon Nitride ignitor manufactured by  
White-Rodgers must be used. These ignitors are spe-  
cially designed to operate with the 50A66-843's adap-  
tive ignition routine to ensure the most efficient ignitor  
temperature.  
#1  
#2  
60 sec.  
90 sec.*  
120 sec.  
180 sec.  
Off  
Off  
On  
On  
Off  
On  
Off  
On  
At the end of the ignitor warm-up time, both valves in the  
gas valve are opened. Flame must be detected within 4  
seconds.  
COOL delay-  
to-fan-off:  
Set switch  
#3  
2 sec.  
45 sec.*  
Off  
On  
If flame is detected, the delay-to-fan-on period begins.  
After the delay-to-fan-on period ends, the circulator fan is  
energized at heat speed. If there is an optional electronic  
air cleaner on the system, the electronic air cleaner and  
the humidifier are energized. When the thermostat is  
satisfied, the gas valve is de-energized. After proof of  
flameloss, theinducerblowerremainsenergizedtopurge  
the system for 5 seconds and the delay-to-fan-off period  
begins. When the purge is complete, the inducer blower  
andhumidifierarede-energized.Afterthedelay-to-fan-off  
period ends, the circulator fan and electronic air cleaner  
*Factory Setting  
HEAT MODE  
In a typical system, a call for heat is initiated by closing the  
thermostat contacts. This starts the 50A66-843 control’s  
heating sequence.The inducer blower and humidifier are  
energized. After a 15-second pre-purge period, the 768A  
Silicon Nitride ignitor is powered.  
This controller has an adaptive algorithm that reduces are de-energized.  
ignitor temperature to slightly greater than the minimum  
If flame is not detected, both valves are de-energized,  
temperature required to ignite gas in each particular  
application. The control measures the line voltage and  
determines an initial ignitor temperature setting based  
on the measurement. After each successful ignition, the  
control lowers the ignitor temperature slightly for the next  
ignition attempt.The control continues to lower the ignitor  
temperature until ignition does not occur, and the control  
the ignitor is turned off, and the 50A66-843 control goes  
into theretrysequence.Theretrysequence provides a  
15-secondwaitfollowinganunsuccessfulignitionattempt  
(flame not detected).After this wait, the ignition sequence  
is restarted. If this ignition attempt is unsuccessful, three  
more retries will be made before the control goes into  
system lockout.  
5
 
OPERATION  
If flame is detected, then lost, the 50A66-843 control will  
repeat the initial ignition sequence for a total of three  
"recycles". After three unsuccessful "recycle" attempts,  
the control will go into system lockout.  
COOL MODE  
In a typical system, a call for cool is initiated by closing  
the thermostat contacts. This energizes the 50A66-843  
control's cooling sequence.The compressor is energized  
and the delay-to-fan-on period begins. After the delay-  
to-fan-on periods ends, the circulator fan is energized at  
cool speed. The electronic air cleaner (optional) is also  
energized. After the thermostat is satisfied, the compres-  
sorisde-energizedandthedelay-to-fan-offperiodbegins.  
After the delay-to-fan-off period ends, the circulator fan  
and electronic air cleaner (optional) are de-energized.  
If flame is established for more than 10 seconds after igni-  
tion,the50A66-843controllerwillcleartheignitionattempt  
(or retry) counter. If flame is lost after 10 seconds, it will  
restart the ignition sequence.This can occur a maximum  
of four times before system lockout.  
A momentary loss of gas supply, ame blowout, or a  
shorted or open condition in the flame probe circuit will be  
sensed within 2 seconds. The gas valve will de-energize  
andthecontrolwillrestarttheignitionsequence.Recycles  
will begin and the burner will operate normally if the gas  
supply returns, or the fault condition is corrected, before  
the last ignition attempt. Otherwise, the control will go  
into system lockout.  
MANUAL FAN ON MODE  
If the thermostat fan switch is moved to the ON position,  
the circulator fan (heat speed) and optional electronic air  
cleaner are energized. When the fan switch is returned  
to the AUTO position, the circulator fan and electronic air  
cleaner (optional) are de-energized.  
If the control has gone into system lockout, it may be pos-  
sible to reset the control by a momentary power interrup-  
tionoftensecondsorlonger.RefertoPRECAUTIONARY,  
SYSTEM LOCKOUT, AND DIAGNOSTIC FEATURES.  
SYSTEM LOCKOUT AND DIAGNOSTIC FEATURES  
2. Interrupt the 24 VAC power at the control for at least  
SYSTEM LOCKOUT FEATURES  
ten seconds. You may also need to reset the flame  
rollout sensor switch.  
Whensystemlockoutoccurs,thegasvalveisde-energized.  
The circulator blower is energized at heat speed for some  
faults, and if flame is sensed, the inducer blower is en-  
ergized. The diagnostic indicator light will flash or glow  
continuously to indicate system status. (System lockout  
will never override the precautionary features.)  
3. Afteronehourinlockout,thecontrolwillautomatically  
reset itself.  
DIAGNOSTIC FEATURES  
To reset the control after system lockout, do one of  
the following:  
The 50A66-843 control continuously monitors its own  
operation and the operation of the system. If a failure oc-  
curs, the DS 1 (red) and DS 2 (green) LEDs will indicate  
a failure code as shown on next page.  
1. Interrupt the call for heat at the thermostat for at least  
onesecond,butlessthan20seconds(ifameissensed  
with the gas valve de-energized, interrupting the call  
for heat at the thermostat will not reset the control).  
6
 
TROUBLESHOOTING  
DIAGNOSTIC TABLE  
DS 1 (Red)  
DS 2 (Green)  
Error/Condition  
Comments/Troubleshooting  
Simultaneous  
Simultaneous slow  
Normal operation  
No fault  
slow flash  
flash  
Simultaneous  
fast flash  
Simultaneous  
fast flash  
Normal operation with call Normal operation  
for heat  
Slow flash  
On  
Open limit switch  
Verify continuity through rollout switch circuit  
Off  
Slow flash  
Pressure switch stuck  
closed/open  
Pressure switch stuck closed. Check switch func-  
tion, verify inducer is turning off.  
Pressure switch stuck open. Check pressure switch  
function and tubing. Verify inducer is turning on and  
pulling sufficient vacuum to engage switch.  
Alternate  
slow flash  
Alternate slow flash External lockout (retries)  
Failure to sense flame is often caused by carbon  
deposits on the flame sensor, a disconnected or  
shorted flame sensor lead or a poorly grounded  
furnace. Carbon deposits can be cleaned with em-  
ery cloth. Verify sensor is not contacting the burner  
and is located in a good position to sense flame.  
Check sensor lead for shorting and verify furnace  
is grounded properly.  
Slow flash  
Off  
Flame sensed with gas  
valve de-energized  
Verify the gas is operating and shutting down prop-  
erly. Flame in burner assembly should extinguish  
promptly at the end of the cycle. Check orifices and  
gas pressure.  
On  
On  
Slow flash  
Open rollout switch  
Verify continuity through rollout switch circuit.  
On  
Module – internal fault  
condition  
Module contacts for gas valve not operating or  
processor fault. Reset control, if condition persists,  
replace module.  
Slow flash  
Fast flash  
Low flame sense current  
Low flame sense current is often caused by carbon  
deposits on the flame sensor, a poorly grounded  
furnace or a mis-aligned flame sense probe.  
Carbon deposits can be cleaned with emery cloth.  
Check or improve furnace and module ground.  
Verify sensor is located in or very near flame as  
specified by the appliance manufacturer.  
Fast flash  
Slow flash  
Grounding or reversed  
polarity  
Verify the control and furnace are properly ground-  
ed. Check and reverse polarity (primary) if incorrect.  
Alternate fast  
flash  
Alternate fast flash  
Module ignitor contact  
failure  
Fault code indicates the module ignitor contacts  
are not functioning properly. Replace module.  
7
 
White-Rodgers is a business  
of Emerson Electric Co.  
The Emerson logo is a  
trademark and service mark  
of Emerson Electric Co.  
 

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