Rheem R96VA0702317MSA Error Code 33: Over-Temperature Switch (Roll-Out) Open
What Does Code 33 Mean?
A code 33 on the Rheem R96VA0702317MSA means the Manually Reset Limit Control (MRLC), also known as the rollout limit switch, has tripped. This switch is designed to detect flame rollout — a condition where flames escape from the normal combustion area within the heat exchanger and enter the burner compartment. Flame rollout is a serious safety event that can cause fire or carbon monoxide poisoning if left unaddressed. Cooling and fan-only modes continue to work, but the furnace will not provide gas heat.
Rollout occurs when combustion gases cannot follow their normal path through the heat exchanger and out the flue. Instead, they are forced backward and outward, bringing flames into the burner compartment. The most common cause is insufficient venting — a blocked exhaust pipe, an excessively long or restricted flue run, or an intake pipe obstruction can all create enough backpressure to force flame rollout. Other causes include an unstable flame pattern from burner assembly issues, damaged heat exchanger tubes that allow cross-flow, or loose wiring that caused the code to appear without actual rollout.
The rollout limit switch is a manual-reset type by design, meaning a technician must physically press the reset button to acknowledge this serious fault. Resetting the switch without identifying and correcting the root cause is dangerous — the rollout condition will simply recur.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Insufficient venting through either the inlet or exhaust | Most common | ✗ Call a pro → |
| Loose or faulty wiring | Common | ✗ Call a pro → |
| Unstable flame pattern | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Call a technician immediately — flame rollout is a serious safety hazard and the furnace must not be restarted until the cause is identified and corrected
- The technician must inspect the venting system for blockages, check the heat exchanger and burner assembly for damage or misalignment, and manually reset the rollout switch only after the root cause is repaired
✓ Verified against manufacturer service manual — March 2026