Rheem two blinks: the draft proving circuit stopped the sequence
Rheem two blinks reports a pressure switch condition on the furnace control. See what the switch proves, what it cannot, and which observations matter.
What this means
Two blinks on a Rheem furnace control identifies a pressure switch condition in the draft proving circuit. The switch is the device that tells the control whether the inducer has established the airflow the burner needs, so the blink count locates the circuit that failed to reach its expected state rather than the part that caused it.
Equipment and model context
Rheem R96V modulating condensing gas furnaces documented in the Rheem service literature
- R96VA0601317
- R96VA0851521
- R96VA1152521
This reading follows the diagnostic table published for the Rheem R96V modulating condensing furnace. Rheem and Ruud have used different blink assignments across control generations, and a chart written for another Rheem furnace line can give a different meaning for the same count. Match the model on the rating plate.
What you may notice
- The inducer starts, runs for its period, and the sequence ends with no ignition attempt at all.
- Two distinct blinks repeat with a longer pause between groups on the diagnostic indicator.
- The furnace performs normally in mild conditions and fails during freezing or stormy weather.
Likely causes
- Restriction at the vent or intake termination alters the pressure difference the switch is measuring.
- Condensate collecting in a pressure tube, in the trap, or in the collector box interferes with the signal reaching the switch.
- An inducer that is producing less airflow than it should, whether from deposits on the wheel or a motor condition, cannot satisfy the switch.
Diagnostic paths
You hear the draft motor but never the burner
The inducer is audible for its full run, then the furnace falls silent, and the igniter never glows and no gas sound occurs.
Stop the heating call and inspect the terminals outdoors from where you stand. A draft motor that completes its run without the sequence advancing is the signature of this circuit.
The fault arrives with hard frost and leaves with a thaw
Failures cluster on the coldest mornings and the furnace behaves normally once temperatures rise, over repeated cycles of weather.
Log the outdoor temperature each time. Ice in a termination or a condensate path is a seasonal mechanism that a parts-based diagnosis will miss.
Water is visible around the furnace base
Standing water, staining, or damp is present under or around the furnace cabinet, whether or not the code is showing at that moment.
Photograph it and report it alongside the code. Condensate leaving its intended path and a draft proving fault are connected on this type of furnace.
Pressure difference, not airflow, is the measured quantity. The inducer creates a difference between the collector box and the reference the switch sees, and anything that changes that difference changes what the switch reports.
- Inducer runsCreates a pressure difference
- TubingCarries the signal to the switch
- SwitchCloses when the difference is enough
- ControlAllows ignition only once it closes
| Pattern | Likely area | What to record |
|---|---|---|
| Only in freezing weather | Terminations or condensate freezing | Outdoor temperature each time |
| Only in high wind | Vent termination behaviour | Wind direction each time |
| Regardless of conditions | Inducer, switch, or wiring | That conditions made no difference |
| Worse over months | Gradual deposit or component wear | When it first started |
The switch is a messenger, and messengers get blamed
There is a reason pressure switches are replaced more often than they fail. They are the component named on the code, they are inexpensive, and swapping one is quick. None of that makes the switch the cause. The device reports a pressure difference, and the difference is produced by an inducer, carried by tubing, and influenced by everything the flue gas passes through on its way out of the building.
A furnace that faults again a fortnight after a new switch was fitted is the ordinary outcome of skipping that reasoning. Measuring the pressure the switch is actually seeing, and comparing it against the value the literature specifies, is what separates a switch that is lying from a switch that is telling the truth about a poor draft.
Condensing furnaces make this a seasonal fault
A furnace that condenses its flue gas is producing liquid water inside components that also carry pressure signals. That gives freezing weather two separate ways to cause this code: ice at the termination restricting the flow, and ice in a drain or tube blocking the signal. Both disappear when the weather turns, which is exactly why an owner's weather log is worth more here than on most faults.
Reporting the pattern also protects you from an unnecessary repair. A technician told that the fault only happens below freezing has a reason to inspect terminations and condensate paths first. The furnace pressure switch reference explains the proving sequence, and the frozen condensate guide covers what ice in the drain does to a condensing appliance.
What to give the technician
Tell the technician the Rheem model and serial number, the two-blink count, whether the inducer ran, whether ignition was attempted, the weather at each failure, and any water seen around the furnace.
Safe homeowner checks
- Count the blinks carefully, since two blinks and three blinks are easy to confuse when the pause between groups is short.
- View the vent and intake terminations from ground level and note ice, snow, nests, or vegetation without climbing or reaching in.
- Record the outdoor temperature, wind, and whether ignition was ever attempted on each failed cycle.
Is a reset appropriate?
Interrupting power clears the indication and the control repeats the same proving test on the next call. Where the cause is seasonal, an apparent fix after a reset may only be the weather changing.
When to call a technician
- Measuring draft pressure against the published value, inspecting the inducer wheel, and clearing condensate paths are licensed gas-furnace tasks.
- A pressure switch must never be bridged or bypassed to make a furnace run, because it is the only device confirming that combustion products are leaving the building.
Questions people ask about this
Should I just replace the Rheem pressure switch?
The switch reports a pressure difference that the inducer and the vent system create. Replacing it without measuring what it is seeing leaves a poor draft, an obstruction, or a condensate problem in place.
Why does my Rheem furnace only fail on cold mornings?
A condensing furnace can ice at the termination and inside condensate paths, and either will change the pressure the switch measures. Both effects come and go with the weather rather than with any component.
Is two blinks the same on a Ruud furnace?
Rheem and Ruud share engineering across several ranges, but blink assignments belong to a control platform and generation. Read the diagnostic label on the furnace in front of you rather than assuming the tables match.
Evidence recordHow this page was checked
service manual, official manufacturer support article · checked 2026-09-15
Every technical claim above was written from primary documentation held in the HVAC Bench evidence record: Rheem technical literature. Where a source limits a definition to certain models, test conditions, or product classes, that limit is repeated here rather than generalised.
- Documentation class
- service manual, official manufacturer support article
- Scope of the definition
- Rheem R96V modulating condensing gas furnaces documented in the Rheem service literature
- Last checked
- 2026-09-15