Rheem/Ruud Furnace Error Codes and Troubleshooting
Rheem and Ruud furnaces share the same parent company and, importantly, the same control board fault code system. If you own a Rheem Classic, Classic Plus, Prestige, or a Ruud Achiever or Silhouette furnace, the LED blink codes on the control board follow the same logic. This guide explains what each flash pattern means, what you can check without tools, and when the situation calls for a licensed HVAC technician.
Reading Rheem/Ruud Blink Codes
The status LED is located on the main control board, typically visible through a small viewport on the blower compartment door. The LED blinks a primary count (e.g., 2 flashes), pauses for about 3 seconds, then blinks a secondary count (e.g., 1 flash). Together, these form the fault code. Some models also flash a red and green LED simultaneously or in alternation to indicate specific states like normal operation or lockout.
Note: The green LED blinking slowly (one flash every 2 seconds) during a heating call is normal — it indicates the inducer is running prior to ignition. A rapid green flash pattern typically means the call for heat is satisfied. Fault codes are typically indicated by red LED patterns.
Common Rheem/Ruud Furnace Fault Codes
| Flash Code | Meaning | What to Do |
|---|---|---|
| 2 flashes | Pressure switch stuck open — vent or drain issue | Check flue vent and condensate drain |
| 3 flashes | Pressure switch stuck closed before inducer starts | Technician required |
| 4 flashes | Open high-limit — overheating | Replace filter; check for blocked vents |
| 5 flashes | Flame detected with no call for heat | Technician required — shut off gas if concerned |
| 6 flashes | 115V power polarity or grounding fault | Licensed electrician required |
| 7 flashes | Gas valve circuit fault or weak flame signal | Technician required |
| 8 flashes | Ignitor failure | Technician required — ignitor replacement likely needed |
| 9 flashes | Rollout switch open — flame rollout | Shut off furnace; call immediately — safety hazard |
| Rapid red flash | System in lockout after failed ignition attempts | One reset attempt; call tech if code returns |
| Green + Red alternating | Communication fault (two-stage or variable-speed models) | Technician required |
Condensate Drain: A Rheem/Ruud-Specific Check
High-efficiency Rheem and Ruud furnaces (90%+ AFUE) produce condensate — water vapor that drains through a PVC drain line. If this line clogs, it backs up into the pressure switch hose and triggers a pressure switch fault (2 flashes). Check the condensate drain line for kinks, clogs, or frozen sections. A clogged drain is a common Wisconsin winter problem and is often cleared with warm water or a wet/dry vacuum.
What Homeowners Can Check
Air filter: Replace the filter if it appears dirty or if the 4-flash (high-limit) code appears. Rheem and Ruud furnaces are sensitive to restricted airflow.
Vents and registers: Ensure all supply registers throughout the home are open and that return air vents are not blocked.
Gas shutoff: Confirm the manual gas shutoff valve near the furnace is open (handle parallel to the pipe).
Power: Check the circuit breaker and the furnace power switch. A common source of confusion is the wall switch near the furnace being accidentally turned off — it looks like a light switch.
Condensate drain: For 2-flash pressure switch codes on high-efficiency models, inspect and clear the condensate drain line as described above.
When to Call a Professional
If you see a 9-flash rollout code, a 5-flash "flame without call" code, or any code that returns after a single reset, call a technician. Rheem and Ruud furnaces with flame rollout have a safety switch that must be manually reset by a technician after the root cause is identified and corrected — the switch cannot be bypassed.
Burkhardt Heating, Cooling, Plumbing & Electric serves Southeastern Wisconsin homeowners with Rheem and Ruud equipment repair, maintenance, and replacement, with 24/7 emergency availability.
Fast Rheem/Ruud Furnace Repair in Wisconsin
Fault codes are designed to protect your system and your family. Acting on them quickly — and correctly — keeps a minor issue from becoming a full system failure in the middle of winter.
If you see any of these codes, call Burkhardt at 414-206-3049. Our NATE-certified technicians can diagnose and repair the issue — usually in a single visit.
Ready to schedule service? Call Burkhardt Heating, Cooling, Plumbing & Electric at 414-206-3049 or contact us online. Available 24/7 for emergencies.
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