Carrier Performance 96 / Comfort 96 gas furnaces (59TP6, 59SP6, 59SC6): quick sheet

Covers: Carrier condensing gas furnaces: Performance 96 two-stage 59TP6 (variable 25-speed blower), Performance 96 single-stage 59SP6, and Comfort 96 single-stage 59SC6 (multi-speed blower); earlier 59SC5 / 59TP5 generation is similar. Bryant sells equivalent platforms.

Single sourceBrands: Carrier, Bryant7 components

Carrier's high-volume 96% furnaces. The board flashes a two-digit status code (e.g. 3 flashes, pause, 1 flash = 31) on an LED visible through the blower door; a code label is on the door. Gas valve, burners and venting are blocked; inducer, pressure switch, condensate, limits and blower are tech territory.

Safety first

Gas valve, burners, manifold pressure and vent pipe changes are blocked: licensed gas technician only.
Turn off power and gas before opening the burner compartment; 120 V at the board.
Code meanings vary by board: always confirm on the door label.

How it works

Call for heat → inducer runs → pressure switch proves draft → hot-surface igniter heats → gas valve opens → flame proven → blower starts after a delay.

59TP6: two-stage valve runs low stage most of the time; variable 25-speed blower. 59SP6: single-stage valve with variable blower. 59SC6: single-stage valve with multi-speed blower.

Condensing secondary heat exchanger produces condensate, drained through a trap; a blocked trap is a top cause of pressure-switch faults.

Works with the ecobee for Carrier smart thermostat (InteliSense diagnostics).

Components & tests

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.

Diagnostic guides for this appliance

Component test · Furnace

How to test a gas furnace draft pressure switch (electrical and draft checks only)

The pressure switch proves the inducer is pulling enough draft before ignition is allowed. Test it with a meter (24 V across it) and a manometer against the set point printed on the switch. Gas valve, gas pressure and burner work are not covered: refer those to a licensed gas technician.

5 steps ~30 minadvanced

Guide · Furnace

Furnace runs no heat (blower only or nothing)

Start with the board LED code, then work the call path: thermostat, 24 V, safeties, inducer, ignition, flame proving. Most no-heat calls end at a filter, a flame sensor, a pressure switch issue or gas being off.

5 steps ~45 minmoderate

Guide · Furnace

Furnace short cycling (starts and stops quickly)

Short cycling is usually a safety opening mid-cycle (limit from low airflow, flame sensor dropping out, pressure switch opening) or a thermostat issue. Read the code and time the cycle.

4 steps ~45 minmoderate

Other furnaces manuals

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90%+ condensing gas furnace: field service manual

High-efficiency condensing furnaces (about 90-98% AFUE) with a secondary heat exchanger, PVC venting and a condensate trap; single-stage, two-stage and modulating

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Electric furnace / air handler with heat strips: field service manual

Electric furnaces and air handlers with resistance heat strips, sequencers or relays, and limits/thermal links

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