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Carrier · Furnace

12 Blower on after power-up (normal)

Low severity 59TP6A58SB0A/58SB1A

What the control is telling you

Normal: if power is restored during a heat call, or R-W/W1 opens during the blower on-delay, the blower runs 90 seconds and the LED flashes 12 until it finishes.

Applies to: 59TP6A two-stage variable-speed ECM multipoise condensing gas furnace, all sizes (040-10 to 120-22)

Likely causes

  • Power interruption (115 V or 24 V) during a call for heat
  • Heat call ended during blower on-delay

Test and repair steps

  1. Wait out the 90-second blower-only period; the control starts it 2 seconds after power returns if heat is still called.
  2. Confirm the LED goes to continuous ON afterward and the furnace responds normally to the thermostat.
  3. If it repeats often, look for intermittent power: loose supply connections, door switch, or breaker.
  4. Note a power interruption also erases the adaptive-heat history, so the next cycle may run low heat up to 16 minutes before high heat.

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Source: Carrier 59TP6A Installation, Start-up, Operating and Service Instructions, Fig. 66 Troubleshooting Guide, p.88; Sequence of Operation, p.85. Summarized in our own words; check the original manual for your model.

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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.