White Rodgers 21D83M-843 Furnace User Manual


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7
DIAGNOSTIC TABLE
DS 1 (Red) DS 2 (Green) Error/Condition Comments/Troubleshooting
Simultaneous
slowash
Simultaneous slow
ash
Normal operation No fault
Simultaneous
fastash
Simultaneous
fastash
Normal operation with call
for heat
Normal operation
Slowash On
Open limit switch Verify continuity through rollout switch circuit
Off Slowash
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ash
Alternateslowash
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ash 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ash
Open rollout switch Verify continuity through rollout switch circuit.
On On
Module – internal fault
condition
Module contacts for gas valve not operating or
processor fault. Reset control, if condition persists,
replace module.
Slowash Fastash
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ash Slowash
Grounding or reversed
polarity
Verify the control and furnace are properly ground-
ed. Check and reverse polarity (primary) if incorrect.
Alternate fast
ash
Alternatefastash
Module ignitor contact
failure
Fault code indicates the module ignitor contacts
are not functioning properly. Replace module.
GLOSSARY
TROUBLESHOOTING
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