Rheem Furnace Error Codes Two Blinks: Meaning, Causes, and Fixes

The Rheem furnace two-blink error code commonly indicates a problem with the unit’s safety and combustion sequence, most often related to the pressure switch or ventilation system. This article explains what two blinks mean, likely causes, step-by-step troubleshooting, safety precautions, and when to contact a professional for repairs.

Indicator	Typical Meaning	Common Causes
2 Blinks	Pressure Switch Open / Draft Or Flame Ignition Issue	Blocked venting, failed pressure switch, inducer motor problem, condensate blockage, wiring fault

What Two Blinks On A Rheem Furnace Means

Rheem furnaces use LED blink codes to communicate faults during startup and normal operation. Two blinks typically signal a problem in the air-pressure/draft-sensing circuit where the pressure switch fails to close when the inducer motor runs or a flame/detection issue prevents normal ignition sequence continuation.

How The Furnace Ignition Sequence Works

Understanding the sequence clarifies why a pressure issue triggers two blinks. The sequence begins with a thermostat call for heat, inducer motor startup to create combustion airflow, the pressure switch closing to confirm draft, ignition of gas, and flame sensing. Any interruption in these steps causes safety codes.

Key Components Involved

• Inducer Motor: Creates draft through the heat exchanger and vent.
• Pressure Switch: Detects correct airflow and closes to allow ignition.
• Flame Sensor/Ignitor: Ignites gas and confirms flame presence.
• Vent/Exhaust Path: Moves combustion products safely outside.

Common Causes Of Two-Blink Errors

Multiple faults can lead to the two-blink code. The most frequent causes include environmental and mechanical issues that prevent the pressure switch from closing or prevent safe ignition.

Blocked Or Restricted Venting

Obstructions in the vent pipe or chimney, ice or nests at the termination, or collapsed vent sections can reduce airflow. Restricted venting prevents the inducer from creating sufficient negative pressure for the pressure switch to close.

Failed Or Sticky Pressure Switch

The pressure switch may fail electrically, its tubing can be cracked or disconnected, or it may stick mechanically. A faulty pressure switch will not register the inducer-created draft and keeps the control from progressing to ignition.

Inducer Motor Problems

A weak, seized, or electrically defective inducer motor cannot produce required draft. Inducer issues will stop the pressure switch from closing and cause the two-blink fault.

Condensate Or Drain Blockage (High-Efficiency Units)

Condensate backed up into the pressure switch tubing or drain can cause false readings or restrict airflow in high-efficiency furnaces, triggering the two-blink code.

Wiring And Control Board Faults

Broken, corroded, or loose wires between the pressure switch and control board, or a control board malfunction, can mimic a pressure switch failure and produce two blinks.

Step-By-Step Troubleshooting For Two Blinks

Technicians and knowledgeable homeowners can follow a safe, systematic troubleshooting approach. Always turn off power and gas before inspecting internal components. If unsure, contact a licensed HVAC technician.

1. Observe The Sequence And Note Symptoms

Record whether the inducer motor starts, whether the furnace attempts ignition, and any unusual sounds or smells. This helps isolate whether the issue is airflow or flame detection related.

2. Check Outdoor Vent Termination

Inspect the vent cap for obstructions such as bird nests, debris, leaves, or ice. Clear visible blockages and test the furnace again to see if the code clears.

3. Inspect Vent Pipes And Elbows

Look for crushed, disconnected, or sagging sections that impede exhaust. Replace damaged venting and ensure correct slope for condensate drainage in category IV appliances.

4. Verify Inducer Motor Operation

When the furnace calls for heat, verify that the inducer motor spins smoothly. A humming sound without rotation indicates mechanical seizure or bad capacitor/motor failure.

5. Examine Pressure Switch Tubing And Connections

Check the rubber tubing from the inducer housing to the pressure switch for cracks, blockages, or disconnections. Replace damaged tubing and ensure tight fittings.

6. Test The Pressure Switch (If Qualified)

A multimeter can check for continuity when the inducer runs. The switch should be closed (continuity) when the inducer creates draft. If the switch doesn’t close, replace it. Only qualified individuals should perform electrical tests.

7. Inspect Flame Sensor And Ignitor

Though two blinks most often point to pressure/draft, a failure to sense flame after ignition attempt could complicate diagnostics. Clean a dirty flame sensor gently or replace a cracked ignitor.

8. Check Condensate Trap And Drain (High-Efficiency)

Clear clogs in the condensate trap and drain. A backed-up drain can cause pressure tubing or inducer housing to fill with water and impair pressure sensing.

9. Review Wiring And Control Connections

Look for loose terminals, burnt connectors, or corroded wires between the pressure switch and control board. Secure and clean connections, and replace damaged wiring.

When To Reset The Furnace And How

Resetting may clear a temporary fault, but it won’t fix underlying mechanical problems. Use the thermostat or service switch to reset, or switch off power at the breaker for 30 seconds. If the two-blink code returns, further diagnosis is required.

Safety Precautions

Combustion systems present risks. Turn off the furnace power and gas before internal inspections. If there is any sign of gas odor, evacuate the area and call the gas company or emergency services. Never bypass safety devices like the pressure switch.

Parts That Commonly Require Replacement

Based on field experience, the most commonly replaced components tied to two-blink faults are the pressure switch, inducer motor, vent sections, and damaged pressure tubing. Flame sensors and ignitors are also frequent repairs when ignition issues coexist.

Costs And Timeframe For Repairs

Repair costs vary by part, labor rates, and region. Typical quick fixes like clearing vents or replacing tubing are low cost. Replacing a pressure switch or inducer motor is more expensive and can range from a couple hundred to several hundred dollars. Professional diagnosis usually takes 30–90 minutes.

When To Call A Professional

Contact a licensed HVAC technician when electrical testing, inducer motor replacement, pressure switch replacement, or control board diagnosis is needed. A professional is required for gas-valve work and to ensure safe, code-compliant venting repairs.

Preventive Maintenance To Avoid Two-Blink Faults

• Schedule annual furnace inspections and cleanings to catch wear before failure.
• Keep outdoor vent terminations clear and protected with guards where appropriate.
• Replace aged or cracked pressure tubing during routine service.
• Maintain condensate drains and traps on high-efficiency units.
• Change air filters regularly to reduce airflow-related stress on the system.

Model Variations And Where To Check Exact Codes

Different Rheem and Ruud models may have slight variations in LED blink definitions. Always consult the specific unit’s data plate and the manufacturer’s service manual for exact code definitions and wiring diagrams. Manufacturer resources and PDFs are available on Rheem’s official website.

Additional Resources And Documentation

• Rheem Official Support — Manuals and technical bulletins.
• AHRI — Standards and certified equipment listings.
• Local licensed HVAC contractors — For on-site diagnosis and safe repairs.

Quick Troubleshooting Checklist For Two Blinks

Step	What To Check
Visual Vent Inspection	Outdoor termination clear, no nests/ice
Inducer Operation	Motor spins freely without unusual noise
Pressure Tubing	No cracks, kinks, or disconnections
Pressure Switch	Opens/closes correctly during cycle
Condensate Drain	Clear and flowing on high-efficiency units
Wiring	Tight, clean, and undamaged connections

Key Takeaways

Two blinks on a Rheem furnace most often signals a pressure switch or draft-related issue caused by venting blockages, inducer motor failure, or faulty pressure switch/tubing. Safe, methodical troubleshooting can identify simple fixes; however, electrical or gas-related repairs require a licensed HVAC technician.

For persistent two-blink codes, documented diagnostics from a professional helps ensure the furnace is repaired correctly and safely, restoring reliable heating and protecting occupants from combustion hazards.