Armstrong furnace 6 flashes: Not used — if you are counting six flashes, count again
Allied Air lists six flashes as not used on this control. The table runs from one to thirteen and skips six deliberately, so a genuine six-flash count is not a code — it means the count is wrong.
Applies to: Armstrong Air, AirEase, Concord and Ducane gas furnaces using the Allied Air -02 integrated control, as documented in installation instructions 507330-03, Table 7.
What it means
Every other count on this control from one to thirteen carries a meaning, which makes six conspicuous by its absence. Miscounting is easy on this board and there are three usual reasons. The first is the heartbeat: healthy operation is a slow one-second-on, one-second-off pulse, and someone joining it midway can read a run of pulses as a fault count. The second is starting to count mid-pattern, so a seven-flash code becomes six. The third is the pause — the control separates repetitions with a gap, and a count begun in the wrong place straddles two repetitions. The reliable method is to watch through at least three complete cycles and take the count that repeats, rather than the first one you see.
Most common causes
- Counting from part way through a longer pattern, most often the seven-flash limit code.
- Reading the slow heartbeat as a fault count rather than as normal operation.
- Starting the count in the middle of the pause between repetitions.
- A five or seven flash code miscounted by one in poor light, which is the common case.
How to diagnose it
- Watch at least three full repetitions and take the count that appears every time.
- Note whether the pulses are evenly slow and even in length — that is the heartbeat, not a code.
- If the count settles on seven, that is the primary or secondary limit code, which is a real and common fault.
- If it settles on five, that is Watchguard after failed ignition retries.
- The stored error history is more reliable than counting: this control keeps the last ten codes even through a power cut.
How to fix it
- Nothing to fix on a six-flash reading. Recount first.
- Better still, read the stored error history rather than counting live — it removes the counting problem entirely.
- Once the real count is established, follow the page for that code.
Notes
Worth knowing that a manufacturer skipping a number in a sequence is normal rather than an omission in this site's coverage. ICP does the same with one flash on its SmartValve control.
Related
- Error code recall — The last ten faults, retained even through a power cut
- 7 flashes — Primary or secondary limit open, or Watchguard after three minutes open
All codes for this manufacturer
Armstrong Air, AirEase, Concord and Ducane furnace codes — every code, with what differs between models.
Not sure this is your brand?
The same count means something else on other furnaces. What 6 flashes means on every brand puts them side by side.