FieldBench
Models
Carrierfurnace

59SP6

Performance 96 · single-stage · variable-speed

Carrier Performance single-stage VS 96% (59SP6 current, 59SP5 previous). One solenoid, one PS, VS / 25-speed blower. Two-digit IFC. 32 is not low-fire — there is no high fire. Bryant twin is 926S.

Not 59TP6 / 59TP7 (two-stage, dual PS, W2). Not 59SC5 / 59SC6 Comfort (no Performance VS plug story). Not Infinity.

Diagnose this modelInstall notesBoard cross-refField wiring

AFUE

Up to 96–97% single-stage condensing

Staging

Single-stage · one PS

Blower

VS / 25-speed · setup, not a TP6 two-stage plug map

Sister SKU

Bryant 926S · 59SP5 previous Performance single-stage

This board

Preferred two-digit IFC · single-stage

  • Same 11–14, 21–24, 31, 33, 34, 41, 45 family as other Bryant/Carrier two-digit boards.
  • One draft switch. 31 is that switch. Door-card 32, if printed, is still the only PS — not a 926T low-fire path.
  • No W2 furnace terminal that means high fire. A leftover W2 is unused or an AC stage.

Write the two-digit code before a power cycle. 11 = empty history.

Universal swap

No universal

Single-stage but still a VS blower. 50A55 / S9200U will not drive it.

White-Rodgers

—

ICM

—

Honeywell

—
  • 50A55-843 / 50M56U-843 / S9200U1000.
  • 59TP6 two-stage IFC.

After you pull the dead card

  1. 1OEM Performance single-stage VS IFC.

Field wiring

Written landings for Carrier 59SP6. Not a factory schematic.

Furnace · single-stage 24V
R / C / W / Y / GGas furnace

Conventional single-stage furnace IFC. One W. Cool Y passes through to the outdoor. No ComfortBridge, no ABCD, no W2.

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 → transformer → R120V in, 24V out
  2. 2Call. Stat W → IFC W~24 VAC
  3. 3Draft. IFC → inducer → PS close120V motor, 24V prove
  4. 4Ignite. IFC → HSI120 VAC
  5. 5Gas. IFC → valve~24 VAC
  6. 6Flame. Rod → IFCµA DC
  7. 7Blow. IFC → heat speedAfter flame prove

This indoor

Performance single-stage VS. One W. No W2.

24V single-stage heat

Door card is one-stage. Twin terminal empty unless the job is actually twinned.

Wall thermostat

Single-stage heat/cool. W2 from a leftover two-stage stat does nothing useful.

  • R24V hot from the IFC24V
  • CCommon24V
  • WHeat24V
  • YCool — also starts the outdoor24V
  • GFan24V

Furnace IFC

Transformer lives here. Y out to the outdoor contactor. TWIN empty on a standalone.

  • RHot to the stat24V
  • CCommon — must reach the outdoor24V
  • WHeat call24V
  • YCool in / cool out24V
  • GBlower24V
  • TWINEmpty unless twinned24V

Landing

  • 24VIFC Rstat R

    ~24 VAC hot

  • 24VIFC Cstat Coutdoor C

    Common

  • 24VStat WIFC W

    Heat. Stays in this cabinet.

  • 24VStat YIFC Youtdoor Y

    Cool / contactor

  • 24VStat GIFC G

    Fan. Does not go outdoors.

IFC harness — single-stage heat

After W arrives. This is the gas train, not the thermostat strip.

Transformer + fuse

120V primary. 24V secondary. Dark stat = fuse / door / transformer first.

  • L1 / N120V to the IFCLine
  • XFMR24V to R24V
  • FUSEOn the IFC24V

24V safety chain

Door, limit, rollout in series. Open anywhere kills heat.

  • DOORInterlock24V
  • LIMITMain limit — rise / no airflow24V
  • ROLLOUTManual reset. Do not jumper and leave24V

Inducer + one pressure switch

W → inducer 120V → PS closes → IFC continues. One hose, one switch.

  • IND120V from the IFC to the inducerLine
  • PS24V prove back to the IFC24V
  • HOSESingle hose. Do not add a second because two-stage boards have two.24V

HSI + single valve

Igniter is 120V from the IFC. Valve is 24V. Flame rod is µA DC back to the IFC.

  • HSI120V hot-surface igniter — not 24VLine
  • VALVE24V to the single solenoid24V
  • FLAMEµA DC on the rod. Not a 24V circuit24V

Serial variable-speed ECM

IFC talks to the motor on the serial harness. No F-taps. No dual run cap on this blower.

  • SERIALIFC-to-motor harness. Unplugged motor = CFM / comm fault, not a tap problem24V
  • CFMSet in the IFC menu / model plug / CoolCloud — not a dip switch on most of these24V

Landing

  • LineL1IFCinducer

    120 VAC after W

  • 24VIFCPSIFC

    ~24 VAC prove. Open PS = no ignition.

  • LineIFCHSI

    120 VAC during trial

  • 24VIFCgas valve

    ~24 VAC after flame prove starts

  • 24VFlame rodIFC

    µA DC. Not 24V.

  • LineIFCblower

    IFC heat speed / tap

Prove it

  • 24 VAC from R to C at the IFC. Fuse / transformer first if the stat is dark.
  • W at the IFC under a heat call. Then inducer / igniter / valve per THIS door card.

Do not

  • Do not land a ComfortBridge 1/2 or Infinity ABCD pair on this IFC.
  • Do not hunt W2 / E8 / high-fire on a one-stage door.
  • TWIN must be empty on a standalone.

9-speed tap, PSC, and CT motors share this thermostat landing. The motor is on the IFC harness diagram.

Sequence

  1. 1

    W

    Inducer → single PS must close (31 if not) → HSI → valve → flame (34) → VS blower.

  2. 2

    No W2 path

    There is no high-fire prove and no second solenoid.

Faults on this IFC

Step 1, then 2, then 3. Expected reading and the fail branch sit under each check.

13 / 33

Limit / lockout

warn

Airflow or rollout. 13 is the hardened 33.

  1. 1 Treat this as flame outside the exchanger

    Do not reset the Carrier 59SP6 rollout and walk away. Write the code, kill the call, and look for flame at the burners, crossover, and vestibule before you do anything else.

    Expect: No flame outside the exchanger. Burners seated. Crossover lit.

    If pass: Still inspect secondary / flue / condensate before you reset.

  2. 2 Secondary, condensate, and flue

    Blocked secondary, drowned collector, or a plugged flue pushes flame out the front. Pull the inducer/collector look, confirm the trap is flowing, and check PVC/vent. VS heat CFM / setup — not a 9-speed tap. Filter, coil, return. Rollout is manual reset.

    Expect: Dry collector, open flue, trap clear.

  3. 3 Reset only after the cause is fixed

    Manual-reset rollout. Recurring rollout on Carrier 59SP6 is a CO / fire call — cracked primary, misaligned burners, or a failed secondary. Confirm CO in the space before you leave.

    Expect: One clean cycle after the cause is fixed. No second reset as a repair.

14 / 34

Ignition

lockout

No flame prove. 14 is the hardened 34.

  1. 1 Watch one full try — do not reset

    Write the Carrier 59SP6 code. Watch inducer, HSI glow, valve click, flame, µA. The step that dies is the repair. Resetting only burns another try into a harder lockout. HSI, gas, rod, ground.

    Expect: W → No W2 path

  2. 2 Gas and the valve

    Cock open, inlet pressure, then manifold on the stage that is failing vs the rating plate. 24 VAC at the valve during trial? Coil ohms? A valve that never opens looks like a ‘bad igniter’ if you did not watch the sequence.

    Expect: Manifold: Single-stage plate value — no low/high pair.

  3. 3 Flame prove, then the lockout timer

    Glow + valve + no prove → rod, ground, or IFC sense. Prove then drop → µA / PS / limit. Soft lockouts on this family often auto-reset on a long clock — do not sit on resets.

    Expect: Stable µA after light-off. No new PS/limit code.

24

Fuse

warn

24 V fuse open.

  1. 1 Find the 24 V short before you replace the fuse

    On Carrier 59SP6 an open IFC fuse is a short on W, Y, G, HUM, EAC, or a data pair landed on 24 V. Unplug the thermostat / data harness first. Tstat short, HUM/EAC, valve harness.

    Expect: Fuse out. 24 V transformer still good. Harness isolated.

  2. 2 Replace the fuse with the harness off

    New fuse, harness still off. If it holds, the short is in the field wiring or accessory. Plug one circuit back at a time (W, then Y, then HUM/EAC).

    Expect: Fuse holds with harness off. Dies when the shorted lead lands.

  3. 3 If it blows with the harness off

    Short is on the Carrier 59SP6 IFC or the gas-valve harness. Unplug the valve and try once more. Repeat blow with valve unplugged = IFC.

    Expect: Do not keep feeding fuses into a welded valve coil or a burned IFC trace.

31

PS / draft

lockout

The only pressure switch did not close.

  1. 1 Prove inducer and the live code

    Do not pull power — that clears the Carrier 59SP6 active code. Write 31. Is the inducer spinning on this call? Silent inducer is not a pressure switch. Trap, collector, PVC, wind, inducer. One hose, one switch.

    Expect: 120 VAC at the inducer on a heat call. Wheel turning.

    If fail: 120 VAC missing → IFC / door switch / incoming power. Voltage + dead motor → inducer.

    If pass: Inducer running + this code → trap, hose, switch, vent (step 2).

  2. 2 Trap, collector, and the hose

    A drowned 96% trap will not make collector pressure. Pull the trap, flush it, confirm the collector box and inducer outlet are not full. Hose cracked, off the port, or full of water fakes an open switch. Do not hunt a high-fire hose.

    Expect: Trap flowing, hose dry and downhill, ports not swapped on a two-switch board.

  3. 3 Switch ohms, then vent load

    Ohm the pressure switch: NO, must close when that inducer speed is making the collector setpoint. If the switch is good, walk the PVC — bird screen, ice, long 2" run, wind, shared chase.

    Expect: Pressure switch: One NO switch. Closed only after inducer is up.

    If fail: Replace the open switch only after the vent and trap are proven.

    If pass: Switch closes on draft and the code stays → IFC input.

41 / 44

Blower RPM / calibration

lockout

VS motor vs setup.

  1. 1 Is the wheel free?

    Spin the Carrier 59SP6 blower by hand. Ice, debris, or a seized bearing is not a control problem. Confirm the motor type on this plate — serial ECM, 9-speed tap, or X-13 — before you grab a capacitor. Static, filter, correct setup for the coil tons.

    Expect: Wheel free. Correct motor family for this IFC.

  2. 2 Command vs rotation

    Call for G or heat and confirm the IFC is actually requesting CFM (taps, serial, or communicating). Amp the motor. Locked rotor + a good command = motor. No command = IFC / harness / shared data.

    Expect: Command present. Motor amps in range, not locked.

  3. 3 Static and the wrong motor

    High static will trip current/limit codes and look like a dead motor. Measure TES vs this cabinet. Wrong horsepower or a leftover memory card after a control swap is the other half of this call.

    Expect: Static on the blower chart. Matching motor / shared-data card.

45

Control lockout

lockout

IFC parked. Not Rheem 45.

  1. 1 Write the live code and watch one cycle

    On Carrier 59SP6 read Preferred two-digit IFC · single-stage before you pull power. Write 45 exactly. Watch one full sequence and note which step dies. Find the root two-digit first.

    Expect: W: Inducer → single PS must close (31 if not) → HSI → valve → flame (34) → VS blower.

  2. 2 Prove the circuit this code names

    Use the Carrier 59SP6 door card and the test points on this plate. Isolate the named switch, sensor, or output with a meter — do not swap the IFC first.

    Expect: Pressure switch: One NO switch. Closed only after inducer is up.

  3. 3 Confirm with a number, then the next part

    If the named part measures good, the IFC input/output or a related code on this same plate is next. Do not apply a sister-SKU chart.

    Expect: Pressure switch: One NO switch. Closed only after inducer is up.

Workflows

31 on 59SP6

Inducer running, no light.

  1. 1 Prove the call and the live code

    One pressure switch. Do not pull a 59TP6 dual-hose card.

    Expect: Write whatever Preferred two-digit IFC · single-stage is showing. Write the two-digit code before a power cycle. 11 = empty history.

    If fail: No call at the IFC → stat / harness. Do not change gas parts.

  2. 2 Isolate the first failed step in the sequence

    Trap / PVC / attic ice — still 96% condensing.

    Expect: No W2 path: There is no high-fire prove and no second solenoid.

  3. 3 Confirm with a number, then the next part

    59SC5 is Comfort, not this Performance VS motor.

    Expect: Pressure switch: One NO switch. Closed only after inducer is up. · Manifold: Single-stage plate value — no low/high pair.

    If fail: Stay on this plate. The out-of-range reading is the part.

    If pass: Reading in range → the next step in this workflow is the repair.

Test points

Pressure switch

One NO switch. Closed only after inducer is up.

Manifold

Single-stage plate value — no low/high pair.

Gotchas

  • 59SP5 was incorrectly aliased under 59TP6. It is single-stage. This is the correct plate.
  • 59SC6 18-speed Comfort is not this Performance VS IFC.

Related plates

Install this plate

Install Carrier 59SP6 as Performance 96 · single-stage · variable-speed.

Performance 96 · single-stage · variable-speed

This plate — not the sister SKU

  • Not 59TP6 / 59TP7 (two-stage, dual PS, W2). Not 59SC5 / 59SC6 Comfort (no Performance VS plug story). Not Infinity.
  • 59SP5 was incorrectly aliased under 59TP6. It is single-stage. This is the correct plate.
  • 59SC6 18-speed Comfort is not this Performance VS IFC.

IFC on this door

  • Same 11–14, 21–24, 31, 33, 34, 41, 45 family as other Bryant/Carrier two-digit boards.
  • One draft switch. 31 is that switch. Door-card 32, if printed, is still the only PS — not a 926T low-fire path.
  • No W2 furnace terminal that means high fire. A leftover W2 is unused or an AC stage.

Hardware

  • AFUE: Up to 96–97% single-stage condensing
  • Staging: Single-stage · one PS
  • Blower: VS / 25-speed · setup, not a TP6 two-stage plug map
  • Sister SKU: Bryant 926S · 59SP5 previous Performance single-stage

First fire

  1. 1One pressure switch. Do not pull a 59TP6 dual-hose card.
  2. 2Trap / PVC / attic ice — still 96% condensing.
  3. 359SC5 is Comfort, not this Performance VS motor.

Do not on Carrier 59SP6

  • Not 59TP6 / 59TP7 (two-stage, dual PS, W2). Not 59SC5 / 59SC6 Comfort (no Performance VS plug story). Not Infinity.
  • 59SP5 was incorrectly aliased under 59TP6. It is single-stage. This is the correct plate.
  • 59SC6 18-speed Comfort is not this Performance VS IFC.

Maker literature

FieldBench does not host manufacturer files. Each link opens the maker’s own literature page in a new tab.

  • Carrier residential furnacesLiterature searchProduct pages carry current literature. I/O booklets are typically HVACpartners / dealer.Open manufacturer PDF
  • Carrier HVAC resourcesLiterature searchOwner-facing literature hub. Do not invent a 59-series I/O URL.Open manufacturer PDF
  • Carrier residential furnacesLiterature searchSearch Carrier 59SP6 on the maker’s literature page.Open manufacturer PDF

Warranty and bulletins

Affected models, serial range, symptom, remedy, date. Maker files open on the manufacturer site.

All bulletins

  • Residential limited warranty

    warranty sheet

    Carrier / Bryant registered heat-exchanger terms

    Current 59-series / Evolution / Preferred registered warranty · Limited warranty certificate

    Open factsOpen manufacturer PDF

  • Dealer portals

    dealer

    Where remaining service letters live

    Current-year service letters not on a public literature page · Maker dealer portal

    Open factsOpen manufacturer PDF