Carrier Carrier 58STA/STX 80,000 BTU 80% AFUE Single-Stage Upflow Gas Furnace BLINK-4 Error Fix: LED 4 Blinks — Open High-Limit Switch (Overheating)

Error code BLINK-4 on the Carrier Carrier 58STA/STX 80,000 BTU 80% AFUE Single-Stage Upflow Gas Furnace means: LED 4 Blinks — Open High-Limit Switch (Overheating). The furnace control board LED flashes 4 times, pauses, then repeats. The primary high-limit safety switch has opened because the temperature inside the heat exchanger exceeded safe limits. The furnace shuts down to prevent damage to the heat exchanger and potential safety hazards. This is the MOST COMMON cause of a furnace that runs for a few minutes then shuts off. Causes (in order of likelihood): (1) DIRTY AIR FILTER — the #1 cause. A clogged filter restricts airflow through the heat exchanger, causing it to overheat. Replace the filter immediately. (2) Blocked or closed supply/return vents — ensure all registers in the home are open and unblocked by furniture. (3) Failed blower motor — if the blower isn't running or is running too slowly, heat builds up. Check if you hear the blower running. (4) Blower wheel dirty or clogged — remove the blower assembly and check for dirt/debris on the squirrel cage wheel. (5) Undersized ductwork — if ducts are too small for the furnace BTU rating, chronic overheating occurs.

The most successful fix is "Inspect and Clean Blower Assembly and Verify Blower Motor Operation" (hard difficulty, ~90 minutes). Estimated DIY cost: $0-$15. HomeMD has 2 community-ranked fixes for this error.

This error is rated high severity. You should address it promptly — continued use could cause damage or safety concerns.

Yes — the top-ranked community fix ("Inspect and Clean Blower Assembly and Verify Blower Motor Operation") is rated hard difficulty and takes about 90 minutes. Tools needed: T20 Torx screwdriver, Vacuum with brush attachment, Multimeter, Non-contact voltage tester, Soft cloth.

DIY cost: $0-$15. Professional repair typically costs $150-$300. Many homeowners save money by trying the top-ranked community fix first.

The Carrier Carrier 58STA/STX 80,000 BTU 80% AFUE Single-Stage Upflow Gas Furnace has 8 other known error codes, including: BLINK-1 (LED 1 Blink — System Lockout (Retries Exceeded)), BLINK-2 (LED 2 Blinks — Pressure Switch Stuck Closed), BLINK-3 (LED 3 Blinks — Pressure Switch Did Not Close (Draft Safeguard)), BLINK-5 (LED 5 Blinks — Flame Sensed Without Gas Valve Call (Dangerous)), BLINK-6 (LED 6 Blinks — 115V Power Reversed or Neutral Not Grounded), and 3 more.

Error code BLINK-4 also appears on 3 other Carrier models: 58STA090-1-16 90,000 BTU 80% AFUE Single-Stage Gas Furnace, Carrier 58SB0 Comfort 80 Single-Stage 80% AFUE Gas Furnace, Carrier 59TP6A080E17 80,000 BTU 96% AFUE Two-Stage Gas Furnace with Variable-Speed Blower. The fix may vary by model, so check each model's specific page for tailored repair steps.