Carrier Furnace Code 13: Limit Device Fault Lockout

Quick Answer

Carrier furnace Code 13 (1 short, 3 long LED blinks) indicates the limit device circuit has opened due to overheating. The most common cause is a dirty air filter blocking airflow, which causes heat to build up in the heat exchanger. Check and replace the air filter first. If the filter is clean, inspect for blocked return air vents. Code 13 can also indicate a cracked heat exchanger, which requires professional evaluation. A tripped rollout limit switch requires a manual reset button press inside the cabinet after the cause is corrected.

CarrierFurnaceSeverity: highDifficulty: intermediate78% DIY Success

Time to Fix

15–90 min

Difficulty

intermediate

Parts Cost

$12 – $35

Tools Needed

Multimeter (continuity setting), Flashlight

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Not seeing 13 on your display?

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HUB

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fault code reset procedure

RESET

What Does the 13 Code Mean?

The furnace overheated and the high limit safety switch tripped. Most often caused by restricted airflow from a clogged filter or blocked vents.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Clogged or dirty air filter blocking return airflow40%

Blocked supply or return air registers reducing airflow24%

High limit switch failed and trips at normal temperature14%

Blower motor not running at full speed12%

Cracked heat exchanger allowing combustion gas mixing10%

Symptoms You May Notice

Furnace runs briefly then shuts off without completing heating cycle
Control board shows 1 short blink + 3 long blinks
Blower continues to run after burners shut off (limit switch cooling mode)
House never reaches set temperature on very cold days
Visible cracks or corrosion on heat exchanger panels (requires inspection)

Can you reset a Carrier furnace to clear the 13 code?

If a rollout limit switch tripped (a sub-type of Code 13), locate the manual reset button on the rollout switch body inside the cabinet near the burners. Press and hold it for 2 seconds. For a standard high limit trip, set the thermostat to OFF, wait 5 minutes for the heat exchanger to cool, then set back to HEAT. Always fix the root cause before resetting; repeated tripping without resolution indicates a serious underlying problem.

Tools Required for Diagnosis

Multimeter (continuity setting)FlashlightScrewdrivers (flathead and Phillips)Replacement air filter (correct size for your model)

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

Open the furnace filter compartment and inspect the air filter

Open the furnace filter compartment and inspect the air filter. Hold it up to a light source. If you cannot see light through it, the filter is clogged and is the likely cause of Code 13. Replace with a new filter of the same MERV rating.

Walk through the house and verify that all supply and return air

With power off

With the furnace running

Verify the blower motor is running at correct speed

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
High Limit SwitchHH12ZB193 · $15–$35	HH12ZB193	$15 – $35
Rollout Limit SwitchHH18HA499 · $12–$25	HH18HA499	$12 – $25

Verify part fitment for your Carrier model

Repair vs. Replace Calculator

Appliance Age (Years)7 Yrs

Labor Approach

Our Verdict

REPAIR

Estimated Cost: $24 (Parts) vs $2750 (New Machine)

Frequently Asked Questions

How often should I change the air filter to prevent Carrier Code 13?

Replace a standard 1-inch fiberglass filter every 30-60 days and a pleated MERV 8-11 filter every 60-90 days. Homes with pets or multiple occupants need more frequent changes. A clogged filter is the single most preventable cause of Code 13 on Carrier furnaces.

Can a cracked heat exchanger cause Code 13 on a Carrier furnace?

Yes. A cracked heat exchanger allows hot combustion gases to recirculate into the air stream, which can cause the high temperature limit to trip. More importantly, a cracked heat exchanger is a carbon monoxide hazard. If Code 13 recurs after cleaning the filter and clearing airflow restrictions, have an HVAC technician perform a heat exchanger inspection before running the furnace again.

Is there a manual reset button for Code 13 on a Carrier furnace?

Only the rollout limit switch version of Code 13 has a manual reset button. The button is located on the rollout switch body, which sits near the burners inside the lower cabinet. The standard high limit switch resets automatically once the temperature drops to safe levels. If neither reset resolves the issue, the switch itself may have failed.

My Carrier furnace keeps showing Code 13 even with a clean filter. What else could cause it?

With a clean filter, the next most common causes are: closed or blocked supply registers reducing airflow, a partially seized blower motor running at low speed, a blower wheel caked with dust reducing air volume, or a heat exchanger crack. A technician can perform a combustion analysis and static pressure test to pinpoint which factor is responsible.

How do I test the high limit switch on a Carrier furnace with a multimeter?

Turn off power at the circuit breaker. Disconnect the two wires from the limit switch terminals. Set your multimeter to continuity mode. Touch the probes to the two terminals on the switch. At room temperature, a good limit switch reads closed (beep or near-zero ohms). If it reads open (OL) at room temperature, the switch has failed and needs replacement regardless of whether the furnace overheated.

Related Carrier Furnace Error Codes

Code: HUBCarrier Furnace LED Flash Codes: Complete Fault Code Guide Code: 31Carrier Furnace Code 31: Gas Valve Failure Code: RESETHow to Reset a Carrier Furnace and Clear LED Fault Codes

Models Known to Experience 13 Errors

This repair applies to most Carrier furnaces with this error code. Common model numbers include:

59TP6, 59MN7, 59SP5, 59TP6A, 58PAV

Last verified for technical accuracy on March 14, 2026