Carrier 58MVC Error Code 13: Limit Circuit Lockout

What Does Code 13 Mean?

A limit-circuit lockout means the variable-speed control board shut the furnace down for safety after the high-limit or flame rollout switch signaled an overheat condition. Specifically, the board locks out if the limit or rollout switch stays open for more than 3 minutes, or after 10 successive limit trips during high-heat operation. The 58MVC then auto-resets after 3 hours to try again.

Code 13 is the lockout that follows the active fault reported as code 33 (limit circuit fault). On this step-modulating furnace, the burners fire in low, medium, and high-heat stages, and the variable-speed blower ramps to match. When airflow across the heat exchanger is restricted, the exchanger runs hotter than the limit switch allows and the switch opens. A dirty or clogged filter is by far the most common airflow restriction, followed by closed or blocked supply and return vents.

Because this is a high-efficiency condensing furnace with a tightly matched blower and heat exchanger, even a moderately dirty filter can push high-heat temperatures past the limit. Repeated trips during a single high-heat call accumulate toward the 10-trip lockout, which is why the code often appears on the coldest days when the furnace runs hard.

The flame rollout switch is a separate safety in the same limit circuit, and it requires a manual reset by a technician. If a clean filter and open vents do not clear the problem, or if a rollout switch has tripped, the cause is not a simple airflow issue and needs professional attention.

What You'll Notice

• The furnace heats for a while, then shuts off before the house reaches temperature
• The blower keeps running to cool the furnace even after the burners go out
• No heat at all for up to 3 hours while the board sits in lockout
• The air filter looks gray, clogged, or matted when you pull it
• Some supply registers feel weak or closed off

Common Causes

How This Is Diagnosed

The logical first check is airflow: pull the filter and inspect it, then walk the house to confirm supply and return registers are open and unobstructed. A dirty filter or blocked vents are the causes a homeowner can correct.

If airflow is good but the code returns, a technician looks deeper — a loose blower wheel, a failing variable-speed blower motor, a misaligned limit or limit shield, or a tripped flame rollout switch that needs manual reset. Those checks are inside the burner and blower compartments and are not homeowner tasks.

How to Fix It: Restore Airflow to Clear the Overheat

What You'll Need

• Replacement furnace filter (correct size) 🛒 Find at FiltersFast · 🛒 Find at Amazon
• Flashlight

Steps

1. Turn off power at the furnace switch or breaker and shut off the gas supply Set the furnace disconnect to OFF (or trip its breaker) and close the manual gas shutoff valve before opening any panel. If you smell gas, leave the house immediately and call your gas company from outside.
2. Remove and inspect the air filter Slide out the filter at the furnace or return-air grille. Hold it up to a light — if you cannot see light through it, it is restricting airflow enough to overheat the exchanger.
3. Replace the filter with the correct size Install a clean filter of the exact size printed on the old one, with the airflow arrow pointing toward the furnace. Do not upgrade to a very dense filter that the variable-speed blower cannot pull through.
4. Open and unblock all registers Walk the house and make sure supply and return registers are fully open and not covered by rugs, furniture, or closed doors. This furnace needs its full designed airflow.
5. Restore power and wait out the lockout Turn the furnace switch back ON. If the board is still in its 3-hour lockout, it will resume automatically; you can shorten the wait by cycling the furnace switch off and back on to reset the control.

When to Call a Professional

Contact a licensed HVAC technician if:

• The code returns even with a clean filter and all registers open
• You suspect a flame rollout switch has tripped — it needs a manual reset and a technician must find why it opened
• The blower sounds like it is rubbing or wobbling, which can indicate a loose blower wheel
• There is any sign of soot or scorching around the burner compartment

✓ Verified against manufacturer service manual — March 2026