Rheem R96VA0702317MSA Error Code 33: Over-Temperature Switch (Roll-Out) Open

What Does Code 33 Mean?

Code 33 appears on the Rheem R96V Integrated Furnace Control (IFC) when a Manually Reset Limit Control, commonly called a rollout limit, has opened. There can be more than one of these switches on the furnace. Unlike an automatic limit, a rollout limit stays open once tripped and must be physically reset to acknowledge that a serious fault occurred. Gas heating is disabled while cooling and fan modes continue to work.

This switch trips for one reason: flames have rolled out of their normal path inside the heat exchanger and into the burner compartment. That is a genuine safety event, not an airflow nuisance code. It usually happens when combustion gases cannot travel their normal route through the heat exchanger and out the flue, so they are forced backward and outward, carrying flame with them. On this condensing furnace the most common trigger is insufficient venting, a blocked or restricted exhaust or intake, an over-long flue run, or an obstruction, which builds enough backpressure to push flame into the compartment. An unstable flame pattern from burner issues or a compromised heat exchanger can produce the same result, and occasionally loose wiring posts the code without true rollout.

The manual-reset design is deliberate. Because rollout can involve fire risk and carbon monoxide, the furnace forces a human to investigate before it can run again. A homeowner should never simply press the reset button to make the furnace start, because resetting without correcting the venting or combustion problem lets the dangerous condition recur. On this model, diagnosis and reset are strictly a qualified technician's job.

What You'll Notice

• The furnace will not produce heat, though cooling and the fan-only setting still work
• The IFC display shows a steady 33
• You may see soot, scorching, or heat discoloration around the burner compartment or its front cover
• There may be a hot, burnt, or unusual smell near the furnace after it tried to fire
• The furnace does not restart on its own even after cooling, because the rollout limit is a manual-reset type

Common Causes

How This Is Diagnosed

A technician treats code 33 as a combustion and venting safety investigation, not a quick reset. They inspect the intake and exhaust for blockage, improper termination, excessive length, or obstruction that could force flame rollout, then examine the burners for an unstable or misdirected flame pattern and check the heat exchanger for cracks or damage that let combustion gases cross over. Wiring to the rollout switch is verified as well, since a loose connection can post the code. Only after the root cause is found and corrected does the technician manually reset the limit and confirm a clean, contained burner flame.

When to Call a Professional

This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:

• The IFC shows code 33 and the furnace will not heat
• You see soot, scorching, or heat discoloration around the burner compartment
• There is a burnt or unusual smell near the furnace after it attempted to fire
• The furnace stays off and will not restart on its own after cooling down
• Anytime you are tempted to press a reset button, since flame rollout must be diagnosed before the switch is reset

✓ Verified against manufacturer service manual — March 2026