Bryant 315AAV Error Code 13: Limit Circuit Lockout

What Does Code 13 Mean?

Status code 13 on the Bryant 315AAV indicates a limit circuit lockout. This happens when a safety switch — such as the high-temperature limit, draft safeguard, flame rollout, or blocked vent switch — has been open for longer than 3 minutes, or when 10 successive limit trips occurred during the last heating cycle. The furnace shuts down completely to protect itself from damage.

The limit switch is a safety device that monitors the temperature inside the furnace. When airflow across the heat exchanger is insufficient, the temperature rises above safe levels and the limit switch opens, cutting off the gas burners. The blower continues running to cool things down. If this keeps happening, the furnace escalates to a full lockout.

The most common cause is a dirty or clogged air filter that restricts airflow through the system. Blocked or closed supply and return vents throughout your home can also cause this. Less commonly, a restricted vent, excessive wind conditions, or a defective switch can trigger the lockout. The furnace will automatically attempt to reset after 3 hours.

Common Causes

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. 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 be running at full speed or makes unusual noises
• The flame rollout switch has tripped (a red button on the switch needs manual reset)
• The blower wheel is loose, damaged, or excessively dirty and needs professional cleaning
• The problem occurs repeatedly even with a clean filter

✓ Verified against manufacturer service manual — March 2026