Goodman GMVM970803BN Error Code E3: Open High Limit Switch

What Does Code E3 Mean?

An E3 code on the Goodman GMVM970803BN indicates that the primary high limit switch has opened. This temperature-sensitive safety device is mounted on the partition panel near the heat exchanger compartment. When temperatures inside the furnace exceed safe operating limits, the switch opens the circuit and shuts down the burners to prevent heat exchanger damage. The circulator blower continues running to cool the overheated components, but the furnace will not fire.

The high limit switch trips when airflow across the heat exchanger is insufficient, causing heat to build up rather than being distributed through the duct system. A dirty or clogged air filter is the most common cause — the filter creates a restriction that reduces airflow, leading to progressively higher temperatures inside the furnace. Blocked or closed supply and return registers throughout the home have a similar effect, as the furnace recirculates the same hot air instead of distributing it.

If the filter and registers are not the issue, the problem may involve the circulator blower running at an incorrect speed, restrictive or undersized ductwork, or a wiring problem. The high limit switch on this model is an automatic-reset type, meaning it will reset on its own once temperatures drop to a safe range. However, if the underlying cause is not addressed, the switch will continue to trip.

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 the house immediately and call your gas company from outside.
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 registers are open and unobstructed Walk through every room and check that all supply registers and return grilles are fully open. Move any furniture, curtains, or rugs that may be blocking airflow. Even a few blocked registers can significantly reduce airflow and cause overheating.
4. Inspect the blower area for dust buildup With the power still off, open the blower access panel and use a flashlight to look at the blower wheel. Check for excessive dust buildup on the blades, which can reduce airflow. Also verify the blower wheel is securely attached to the motor shaft and is not wobbling or rubbing against the housing.
5. Restore power and gas, then test the furnace Turn the gas supply valve to ON (parallel to the pipe) and flip the circuit breaker to ON. The high limit switch is automatic-reset, so it should reset once temperatures drop to normal. You can also cycle the power (off for 30 seconds, then back on) to clear the code. Set your thermostat to call for heat and monitor the furnace through a complete heating cycle.

When to Call a Professional

Contact a licensed HVAC technician if:

• The E3 code returns after replacing the filter and confirming all registers are open
• The blower motor does not seem to be running at full speed or makes unusual noises
• The blower wheel is loose, damaged, or heavily caked with dust
• You suspect ductwork may be undersized or poorly routed for the furnace capacity
• The code keeps recurring even with regular filter changes

✓ Verified against manufacturer service manual — March 2026