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21D83M-843

Integrated Single Stage 

Furnace Control Replacement Kit

FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE 
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL 
INJURY AND/OR PROPERTY DAMAGE.

 

 DESCRIPTION

 

 PRECAUTIONS

INSTALLATION INSTRUCTIONS

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
1 – 4" blue wire
2 – Wiring diagrams 

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.
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.
Following installation or replacement, follow manufacturer’s 
recommended installation/service instructions to ensure 
proper operation.

WARNING

!

Failure to comply with the following warnings 

could result in personal injury or property damage.

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.
•  Ensure proper connection of line neutral and 

line hot wires.

EXPLOSION HAZARD

•  Shut off main gas to appliance until installa-

tion is complete.

CAUTION

!

Do not short out terminals on gas valve or primary 

control. Short or incorrect wiring may damage 

the thermostat.

The kit includes the 50A66-843 which is an automatic gas 

interrupted ignition control that employs a microprocessor 

to continually monitor, analyze, and control the proper 

operation of the gas burner, inducer, and fan.
These controls incorporate system fault analysis for quick 

gas flow shut-off, coupled with automatic ignition retry 

upon sensing a fault correction. 

Lennox

White-Rodgers Page

Reference

10M9301 

12L6901

32M8801 

56L8401

50A65-120 

50A65-121

3

PROCEDURE 1

Figure 1, Picture 

1, Table 1, Wiring 

Diagram 5001-6973

24L8501 

63K8901 

97L4801   

50A62-120 

50A62-121 

50A62-820

4

PROCEDURE 2

Figure 1, Picture 

2, Table 2, Wiring 

Diagram 5001-6972

100925-01 

100925-03

17W9201 

23W5101 

30W2501 

69M0801 

69M1501 

83M00 

21D83M-843 

50A66-122 

50A66-123

5

PROCEDURE 3

The 21D83M-843 kit will replace the following Controls:

Follow instructions for replacement of your model num-
ber under the heading 

INSTALLATION.

PART NO. 37-7337C

Replaces 37-7337B

1515

white-rodgers.com

emersonclimate.com

Summary of Contents for White-Rodgers 21D83M-843

Page 1: ...act 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 Ensure proper connection of ...

Page 2: ...idual products of combustion between the failed trial for ignition and the retry period 15 Post Purge The period of time intended to allow for the dissipation of any unburned gas or residual products of combustion at the end of a furnace burner operating cycle Post purge begins at the loss of flame sense 5 Lockout Time ANSI standard rated module timing 250 Heat Delay To Fan On The period of time b...

Page 3: ...cement 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 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 provi...

Page 4: ...ue transformer wire Optional 4 blue wire provided for transformers that have a quick connect terminal 6 Connect the provided 9 pin to 12 pin wiring harness to the unit 9 pin connector 7 Connect the provided 4 pin to 6 pin wiring harness to the unit 6 pin connector 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...

Page 5: ...te with the 50A66 843 s adap tive ignition routine to ensure the most efficient ignitor temperature At the end of the ignitor warm up time both valves in the gas valve are opened Flame must be detected within 4 seconds 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 cle...

Page 6: ...out 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 If the control has gone into ...

Page 7: ...ng 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 Slow flash Open rollout switch Verify continuity through rollout switch circuit On On Module internal fault condition Module contacts ...

Page 8: ...White Rodgers is a business of Emerson Electric Co The Emerson logo is a trademark and service mark of Emerson Electric Co white rodgers com emersonclimate com ...

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