FieldBench
Wiring

Furnace · two-stage 24V

R / C / W1 / W2 / Y / G

R / C / W1 / W2 / Y / G

Two-stage conventional furnace. W1 low fire, W2 high fire. Outdoor staging is Y or Y1/Y2 — separate from the gas valve.

Written circuit description only — FieldBench does not redraw maker schematics. Example: R to W closes on a heat call; verify 24V at W1 before you change the IFC.

Open manufacturer PDF

Heat sequence

  1. 1Power. L1 / N → IFC → R120V / 24V
  2. 2Low. W1 → inducer LOW → LPS → HSI → valve LOWFirst fire
  3. 3High. W2 → inducer HIGH → HPS → valve HIGHSecond solenoid
  4. 4Flame. Rod → IFCµA DC both stages
  5. 5Blow. IFC → heat blowerAfter flame

24V two-stage heat

Door has W1 and W2. Not Infinity. Not ComfortBridge.

Two-stage thermostat

A single-W stat never proves high fire. That is not a weak inducer.

  • R24V hot24V
  • CCommon24V
  • W1Low-fire heat24V
  • W2High-fire heat24V
  • Y / Y1Cool24V
  • Y2Outdoor high if the condenser is two-stage24V
  • GFan24V

Two-stage IFC

W2 is high fire. Do not tee the pressure-switch hoses because there are two stages.

  • RHot24V
  • CCommon to outdoor24V
  • W1Low fire24V
  • W2High fire24V
  • YCool out24V
  • GBlower / cool tap24V

Landing

  • 24VStat W1IFC W1

    Low fire

  • 24VStat W2IFC W2

    High fire. Missing W2 = stuck on low.

  • 24VStat YIFC Youtdoor Y

    Cool

  • 24VC throughout

    Common

IFC harness — two-stage heat

W1 then W2. Low-fire prove is not high-fire prove.

Transformer + fuse

Same 24V transformer as single-stage. Fuse still kills the whole strip.

  • L1 / N120VLine
  • XFMR24V to R24V
  • FUSEOn the IFC24V

24V safety chain

Door, limit, rollout. A limit trip is not an E9 / 32 pressure-switch story.

  • DOORInterlock24V
  • LIMITMain limit24V
  • ROLLOUTManual reset24V

Two-speed inducer + two pressure switches

W1 = inducer low + LPS. W2 = inducer high + HPS. Separate hoses. Do not tee.

  • IND LO120V low-speed inducerLine
  • IND HI120V high-speed inducerLine
  • LPSLow-fire prove24V
  • HPSHigh-fire prove24V
  • HOSESOne hose per switch. Never tee LPS and HPS24V

HSI + two-stage valve

Igniter 120V. Low solenoid on W1. Second solenoid on W2 after HPS closes.

  • HSI120V igniterLine
  • MV / LO24V low-fire solenoid24V
  • HV / HI24V high-fire solenoid24V
  • FLAMEµA DC on the rod24V

9-speed tap ECM

F01–F09 on the harness. Heat tap and cool tap are separate. Not a 14-pin serial motor and not a run cap.

  • F01–F09Speed taps on the IFC / harness24V
  • HEATDefault often F02 — F01 is an E3 generator on many 9-speed doors24V
  • COOL / Y / GCool tap. Wrong tap freezes the coil and looks like LPS outdoors.24V

Landing

  • LineW1IFCinducer LOWLPS

    120V inducer, 24V prove

  • LineIFCHSIvalve LOW

    120V igniter, 24V low solenoid

  • 24VW2inducer HIGHHPSvalve HIGH

    Missing W2 = stuck on low

  • 24VFlame rodIFC

    µA DC

  • LineIFCheat blower

    After flame. Motor class on this plate.

Prove it

  • W1 then W2 at the IFC under a 2-heat call.
  • If it never stages, W2 is missing at the board — not a bad gas valve until that is proven.

Do not

  • Do not convert this to Infinity by landing W on a random terminal.
  • Do not apply AMVC / ARVT ComfortBridge menus or a memory card.

926T / 59TP6 / AR9T96 / GR9T96 / S9V2 / EL296E class. Same landing on 80% metal-vent cousins — the vent is not the wire.

Plates on this landing