Bryant 355MAV Error Code 13: Limit Circuit Lockout

What Does Code 13 Mean?

Status code 13 on the Bryant 355MAV indicates a limit circuit lockout. This happens when the high-limit safety switch or flame rollout switch has been open for longer than 3 minutes, or when 10 successive limit trips occurred during high-heat operation. The furnace shuts down completely to protect itself from overheating damage.

This lockout is the escalated version of code 33 (Limit Circuit Fault). Code 33 is the active warning while a limit switch is open and the blower is trying to cool the furnace down; if that switch stays open past 3 minutes, the board promotes the condition to this code 13 lockout. On a two-stage furnace like the 355MAV, sustained overheating on high-heat is exactly the condition that drives those repeated trips.

The most common cause is a dirty or clogged air filter that restricts airflow through the heat exchanger. Blocked or closed supply and return vents around the home can do the same. Less commonly, a failing variable-speed blower motor or capacitor reduces airflow enough to trip the limit. The control will automatically attempt to reset after 3 hours.

What You'll Notice

• The furnace heats briefly then shuts the burners off, and warm air stops
• The blower keeps running after the burners cut out, trying to cool the furnace
• The home never reaches the thermostat setpoint before the furnace shuts down
• The status LED flashes code 13 (one short flash, three long flashes)
• The furnace appears dead for up to about 3 hours, then attempts to restart on its own

Common Causes

How This Is Diagnosed

The cause is isolated by working from airflow outward. The filter is checked first because a clogged filter is the most common reason the heat exchanger overheats and trips the limit. Next, supply registers and return grilles are confirmed open and unobstructed throughout the home.

If airflow looks adequate, attention turns to the blower — a dusty or loose blower wheel or a weakening motor can starve airflow — and finally to the limit switch itself and its shield for correct alignment. A tripped flame rollout switch is also checked, since it latches and requires a manual reset before the furnace will run.

How to Fix It: Replace the Air Filter and Restore Airflow

What You'll Need

• Replacement air filter (correct size for your system) 🛒 Find at FiltersFast · 🛒 Find at Amazon
• Flashlight

Steps

1. Turn off electrical power at the breaker and shut off the gas supply valve Locate the furnace circuit breaker and flip it to OFF. Turn the gas shutoff valve to the OFF position (perpendicular to the pipe). If you smell gas, leave immediately and call your gas company.
2. Check and replace the air filter Remove the air filter from the return air duct or furnace filter slot. If it is visibly dirty, clogged, or has not been changed in over 3 months, replace it with a new filter of the correct size. Make sure the airflow direction arrow on the new filter points toward the furnace.
3. Verify all supply and return vents are open Walk through every room and ensure all supply registers and return grilles are fully open and not blocked by furniture, curtains, or rugs. Even a few closed vents can significantly restrict airflow and cause overheating.
4. Inspect the blower area With the power off, look at the blower wheel through the access panel opening. Check for excessive dust buildup on the blower blades, which can reduce airflow. Also verify the blower wheel is securely attached to the motor shaft and not wobbling.
5. Restore power and gas, then test Turn the gas supply valve to ON and flip the circuit breaker to ON. Note that the furnace may need up to 3 hours to auto-reset from lockout, or you can reset it by cycling the power (turn off for 30 seconds, then back on). Set your thermostat to call for heat and monitor the furnace through its heating cycle.

When to Call a Professional

Contact a licensed HVAC technician if:

• Code 13 returns after replacing the filter and opening all vents
• The blower motor does not seem to run at full speed or makes unusual noises
• The flame rollout switch has tripped and its red reset button will not stay set
• The blower wheel is loose, damaged, or excessively dirty
• The lockout recurs repeatedly even with a clean filter and clear airflow

✓ Verified against manufacturer service manual — March 2026