Rheem RGRA-07EMAES Error Code 3 Blinks: Limit Circuit Open

What Does Code 3 Blinks Mean?

A 3-blink pattern on the Rheem RGRA-07EMAES status LED indicates that the limit circuit is open. The high-temperature limit switch has tripped because the furnace is overheating. This is a safety mechanism — the limit switch shuts down the burners to prevent the heat exchanger from reaching dangerous temperatures, while the blower continues running to cool things down.

The most common cause is restricted airflow from a dirty air filter. When the filter is clogged with dust and debris, not enough air flows across the heat exchanger to carry heat away. The exchanger temperature rises until the limit switch trips. Closed or blocked supply and return vents throughout the home can cause the same problem.

Other possible causes include a furnace that is over-fired (gas pressure too high or wrong orifice size), rollout switches that need to be manually reset, a failing blower motor that is not moving enough air, or a faulty limit switch. The manual advises checking airflow restrictions first, then limits, then rollouts.

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 (handle 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 or you cannot see light through it, replace it with a new filter of the correct size. Make sure the airflow direction arrow on the new filter points toward the furnace blower.
3. Open all supply and return vents Walk through every room in your home and ensure all supply registers and return grilles are fully open and not blocked by furniture, curtains, rugs, or other objects. Even a few closed vents can cause enough airflow restriction to trigger the limit switch.
4. Inspect the blower compartment With power off, look through the access panel at the blower wheel. If it is heavily coated with dust, this reduces its ability to move air. Also verify the blower wheel is securely attached and not wobbling on the motor shaft.
5. Restore power and gas, then test Turn the gas supply valve to ON (handle parallel to the pipe) and flip the circuit breaker to ON. Set your thermostat to call for heat and monitor the furnace through a complete heating cycle. Watch the status LED for the 3-blink pattern.

When to Call a Professional

Contact a licensed HVAC technician if:

• The 3-blink code returns after replacing the filter and opening all vents
• A flame rollout switch has tripped (small switch with a red reset button on the burner box)
• The blower motor is not running or sounds abnormal
• The furnace overheats within the first few minutes of operation
• You suspect the furnace may be over-fired (gas pressure issue)

✓ Verified against manufacturer service manual — March 2026