FieldBench

Lennox

ML196

Furnace · Merit · single- or two-stage · LED flash · 96%

Merit 96% condensing furnace using the 1–9 single-LED flash chart (or older dual-LED on G-series replacements). No E2xx 7-seg. PVC collector and trap. ML193 is a 93% condensing cousin with the same flash language — not this plate.

Not EL296V (E223/E229 7-seg). Not SLP99V. Not ML180 (same 1–9 numbers, 80% metal vent — opposite 3-flash physics). Not ML193 as this plate (93% condensing cousin — same flashes, different exchanger/vent kit). Not ML296 (two-stage Merit flash, different cabinet).

Walk this in Diagnose

This plate

AFUE
96% condensing · PVC
Display
Single red LED flash chart
Sister / cousin
ML196UH upflow · ML193 93% cousin (same flashes, not this plate)

This board

Merit LED IFC

  • 1 unexpected flame, 2 PS closed, 3 PS open, 4 primary limit, 5 rollout, 6 PS lockout, 7 ignition lockout, 8 flame lost lockout, 9 polarity.
  • LED off = no power. Steady on = idle on many of these.
  • Older G40/G61 dual-LED (DS1/DS2) is a different chart — do not use it here.

Sequence

  1. W. Inducer → PS close (3-flash if not, 2-flash if it was already closed) → HSI → valve → flame → blower.
  2. Lockouts. Repeated 3-flash hardens to 6. Failed light-off hardens to 7. Flame lost after prove hardens to 8.

Faults on this IFC

  • 1 flash

    Unexpected flame

    hazard

    Flame with the valve off.

    • Shut the cock. Leaking valve.
  • 2 flash

    PS closed

    lockout

    Pressure switch is made with the inducer off.

    • Unplug the switch. Water in the hose or a welded disc.
    • 96% residual draft from a shared vent.
  • 3 flash

    PS open

    lockout

    Draft not proven. On this 96% that is trap / PVC / collector — not a chimney.

    • Condensate trap, collector, PVC intake/exhaust, inducer.
    • Do not pull the ML180 metal-vent playbook. Same flash, opposite wet/dry checks.
  • 4 flash

    Primary limit

    warn

    Airflow / overtemp.

    • Tap or PSC speed, filter, coil, rise.
  • 5 flash

    Rollout

    hazard

    Flame containment. Hazard.

    • Exchanger, burners, flue. Reset only after the cause is gone.
  • 6 flash

    PS lockout

    lockout

    Hardened 3-flash / 2-flash. Retries used up on draft.

    • Fix the 3-flash physics (trap/PVC) before you reset.
  • 7 flash

    Ignition lockout

    lockout

    Failed to light / prove flame.

    • HSI, gas cock, valve 24 VAC, rod.
  • 8 flash

    Flame lost lockout

    lockout

    Had flame, then lost it. Retries used up.

    • Rod, ground, manifold after blower-on, vent that starves the flame.
  • 9 flash

    Polarity

    lockout

    L1/N reversed or ground missing.

    • Hot and neutral at the IFC. Chassis ground. Flame sense will not work reversed.

Workflows

3-flash on 96% PVC

No heat, inducer running or not, Merit LED.

  1. Data plate: ML196 = Category IV PVC. This is not ML180 metal vent. Do not cut a chimney story here.
  2. Trap, collector, PVC slope, inducer. A drowned 96% trap is the usual 3-flash.
  3. If you see E223 on a 7-seg, you are not on an ML — go to EL296V.
  4. Repeated 3-flash becomes 6-flash lockout. Fix draft, then reset.

Test points

Flash count
Long pause between groups. Count twice.
Trap
Clear and primed on this 96%. A dry or plugged trap is 3-flash.

Gotchas

  • ML180 uses the same 1–9 numbers. 3-flash there is chimney/inducer, not a drowned trap.
  • ML193 is a 93% condensing cousin — same flashes, not this plate. Still PVC, still not metal vent.
  • ML296 is two-stage Merit with flash codes. EL296V is Elite with E2xx. The names are designed to confuse you.

Related plates

  • lennox-ml180 — Merit 80% metal vent. Same 1–9 flashes, opposite 3-flash physics.
  • lennox-el296v — Elite 96% 7-seg E2xx. If you are counting flashes you are not on that board.