Armstrong furnace Heartbeat: Control powered, no errors detected
A slow steady pulse — one second on, one second off — means the control is powered and has found no errors. Allied Air defines the timing explicitly, which makes it easy to distinguish from a fault code.
Applies to: Allied Air Enterprises A80UH1E and 80G1UHE upflow and horizontal warm air gas furnaces with the -02 integrated control, per installation instructions 507330-03. Allied Air sells the same equipment as Armstrong Air, AirEase, Concord and Ducane, and the controls and codes are shared across those brands.
What it means
Allied Air documents the heartbeat precisely: a slow flash of one second on and one second off, repeating, displayed during all modes of operation when no errors are detected. That precision is unusually helpful. Most manufacturers describe a heartbeat qualitatively and leave you to judge whether what you are seeing is a pulse or a count; here you can time it. Anything faster than one second on, one second off is a fault code, and fault codes on this control flash at roughly half that interval with a three second gap before repeating.
Most common causes
- The control is powered and no error has been detected. This is the intended meaning.
- The furnace may be idle or actively heating — the heartbeat is shown during all modes of operation, so it does not distinguish them.
How to diagnose it
- Time it. One second on, one second off is a heartbeat. Faster flashing with a three second pause before repeating is a fault code.
- Note that the heartbeat appears during every mode, so it tells you nothing about whether the furnace is currently heating.
- If the house is cold and the control shows a heartbeat, the furnace has not been asked to run or cannot act on the request. Check the thermostat first.
- This control stores the last ten error codes even through a power cut, so a heartbeat now does not mean nothing has gone wrong recently — the history can be recalled.
How to fix it
- Nothing to fix if the furnace is heating normally.
- If the house is cold, check the thermostat is set to heat and above room temperature, and replace its batteries.
- If the thermostat is calling and the control still shows only a heartbeat, recall the stored error history before assuming nothing is wrong.
- Do not clear the stored codes before anyone has read them.
Notes
A manufacturer publishing the exact heartbeat timing is worth taking advantage of. It converts "is that a pulse or a code?" from a judgement into a measurement you can make with a watch.
Related
- Error code recall — Ten stored faults that survive a power cut
- LED off — No power, or a control hardware fault
All codes for this manufacturer
Armstrong Air, AirEase, Concord and Ducane furnace codes — every code, with what differs between models.