The short answer
Armstrong Air furnaces in Northern Virginia use one of three code systems, and which one depends on the model and year, not the brand. Older furnaces like the A801D and A951A blink a red light up to 9 times. The 2022 and 2023 single-stage models like the A96UH1E and A951E blink up to 13 times. Two-stage, variable-speed and the 2026 K models show an E and three digits on a small number display. AirEase uses the same model numbers and the same tables.
If you smell gas, skip all of it. Leave the house and call the gas company and 911 from outside. If a carbon monoxide alarm is going off, get everyone out first (what to do when the CO alarm sounds).
Which table is yours
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| What you see through the door window | Example models | Table |
|---|---|---|
| One red light, codes up to 9 flashes | A801D, A951A, A951S, A931A, and the two-stage A952V | Older 9-flash |
| One red light, codes up to 13 flashes, a slow heartbeat when idle | A96UH1E (2022), A951E (2023), A801E | 13-flash |
| A small number display: E and three digits | A97MV, A802V, A972V, and 2026 K models like A96UH1EK, A93UH1EK, A80UH1EK, A97US2VK | E-codes |
The model number is on the sticker inside the furnace door. Allied Air builds Armstrong Air, AirEase, Ducane and Concord, and prints one manual for each matching pair: an Armstrong A96UH1E is a Ducane 96G1UHE. Ducane owners, see Ducane furnace troubleshooting.
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Older 9-flash furnaces (A801D, A951A, A931A, A951S)
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| Flashes | What it means |
|---|---|
| 1 | Flame sensed with the gas valve off |
| 2 | Pressure switch closed with the inducer off |
| 3 | Pressure switch open with the inducer on |
| 4 | High limit open |
| 5 | Rollout switch open |
| 6 | Pressure switch cycle lockout |
| 7 | Lockout: no ignition |
| 8 | Lockout: too many flame dropouts |
| 9 | Incorrect line voltage phasing |
The two-stage A952V uses nearly the same table, with three changes: 3 flashes is the low-fire pressure switch, the rollout or the aux limit; 5 isn’t used; and 9 is incorrect polarity and phasing. It also has a green light for high heat (flashing means the high pressure switch hasn’t closed) and an amber light that counts airflow, one flash per 100 CFM.
2022 and 2023 single-stage, 13 flashes (A96UH1E, A951E, A801E)
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| Flashes | What it means |
|---|---|
| 1 | Reverse polarity |
| 2 | Improper ground |
| 3 | Burner failed to light, or lost its flame |
| 4 | Low flame signal |
| 5 | Watchguard: retries used up, one-hour lockout |
| 6 | Not used |
| 7 | A limit open, or open longer than 3 minutes |
| 8 | Rollout switch open |
| 9 | Pressure switch failed to close, or opened during the heat call |
| 10 | Watchguard: pressure switch opened 5 times in one call |
| 11 | Pressure switch stuck closed before the inducer starts |
| 12 | Flame sensed with the gas valve off |
| 13 | Low line voltage |
A slow, steady blink (1 second on, 1 off) is the heartbeat, which is normal. No light means no power or a board fault, and on the newer board a light that stays solid on means a board fault. The board keeps the last 10 codes: press and release its button to replay them. Holding the button more than 5 seconds erases them, so photograph first.
E-codes on the number display
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| Code | What it means |
|---|---|
| E200 | Hard lockout. It stays off until the power is cycled, and a tech should find why. |
| E223, E224 | Low pressure switch failed open, or failed closed |
| E225, E226 | High pressure switch failed open, or failed closed (two-stage) |
| E227 | Low pressure switch opened while lighting or running |
| E229 | Lit on high fire. No action needed. |
| E250 | Limit open. A one-hour lockout if it doesn’t close within 3 minutes. |
| E270 | No flame after the retries |
| E271, E272 | Retries or recycles used up on a pressure switch problem |
| E273 | Flame failure |
| E274 | Limit |
| E275 | Flame sensed out of sequence |
| E290 | Igniter circuit fault, one-hour lockout |
Soft lockouts on these furnaces last 60 minutes; a hardware fault waits 5 minutes. The older modulating A96MV prints the same numbers without the E, so 250 means E250. E228 (inducer calibration) shows only on the A97MV and A96MV. For the pressure switch codes in every table, see Armstrong Air pressure switch codes.
Flash 3 means two different things
On the older 9-flash table, 3 flashes is a pressure switch problem. On the 13-flash table, it’s a burner that failed to light. Same blink, different part. Check the model year before you go hunting.
What to check before you call
Armstrong’s own “not getting heat” list is a good start: gas on at the meter and at the furnace shutoff, the system switched on, the breaker on, the thermostat on HEAT and set warmer than the room, and a clean filter. Armstrong suggests changing it about every month in heavy use. Then:
Photo the code, then reset once. Move the thermostat from Heat to OFF, wait a few seconds, and back to Heat. Take a photo of the code before you reset anything. A reset can clear what’s showing, and that number saves the tech time and you money.
The furnace also tries again on its own 60 minutes after an ignition lockout. If it locks out twice, the cause is still there. And a rollout code means flame came out of the burner area. Don’t keep resetting that one.
What it usually turns out to be
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| The cause | Codes | Our price |
|---|---|---|
| Cracked igniter | 9-flash 7, 13-flash 3 then 5, E270, E290 | $240 to $410 |
| Dirty flame sensor | 9-flash 8, 13-flash 4, E273 | $95 to $180 |
| Clogged condensate drain | Pressure switch codes | $175 to $420 |
| Pressure switch, inducer or vent | Pressure switch codes | Priced in writing |
| Blower wheel packed with dust | Limit codes | $300 to $440 |
| Control board | Board fault, or codes that make no sense | $550 to $1,180 |
The diagnostic is a flat $99, and the price comes in writing before we start.
Our heating check is $67 per system, through December 31: furnace, heat pump or boiler. On a furnace, for $229 (regularly $467) we also pull the blower wheel and clean it blade by blade.
If the repair is a big one on an older furnace, get a second look before you spend it. Our free second opinion costs you nothing, and the estimator shows what a new system costs with $1,500 off already in the price.
Codes and warning lights from every brand, in one place: furnace and AC error codes.
Call or book a furnace repair
Call (703) 997-9757. We answer day or night. Or book online and pick a time. The diagnostic is a flat $99, and you see the repair price in writing before we touch anything. Furnace running fine and you want to keep it that way? Book the $67 heating check from goswiftpro.com/cookiesoffer (book by November 30) and a box of warm cookies comes with the visit. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276. We work on Armstrong Air, AirEase, Ducane and Concord furnaces all over Northern Virginia: furnace repair.
Questions people ask
How do I read the codes on my Armstrong Air furnace?
Look through the window in the lower door for a blinking red light or a small number display. Count the flashes in one group, or read the E-code, then match it to your model’s table. The model number is on the sticker inside the door.
What does 3 flashes mean on an Armstrong Air furnace?
On older models like the A801D and A951A, it means the pressure switch is open with the inducer running. On the 13-flash models like the 2022 A96UH1E and 2023 A951E, it means the burner failed to light or lost its flame.
How do I reset an Armstrong Air furnace?
Move the thermostat from Heat to OFF and back to Heat. That restarts the lighting sequence. The furnace also retries on its own after 60 minutes. If it locks out again, call.
Are AirEase and Armstrong Air codes the same?
Yes. AirEase uses the same A model numbers and the same manuals as Armstrong Air. Ducane and Concord use matching G model numbers with the same tables.
