The short answer
Read a Luxaire furnace light by its color first. Green is fine, amber means it’s heating (or, on a modulating model, warning you while it keeps heating), red flashes are a fault you count, and a light that stays on without flashing is a failed control board. In Northern Virginia homes the red counts that come up most are 3 (the pressure switch: vent, drain or inducer), 7 (no flame after three tries) and 4 (overheating, usually the filter). Count it twice, change the filter, power cycle once, and call if it comes back.
Where the light is
On the control board, behind a clear window in the lower door, the one over the blower (Luxaire owner’s manual). Keep the door on to read it: pulling it opens a safety switch that cuts the power, and the light goes out with it. You won’t lose anything if it does, because the board keeps its last five codes.
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Green: it’s fine
Swipe to see all columns →
Swipe to see all columns →
| Light | What it means |
|---|---|
| Slow green flash | Power on, nothing calling. Normal |
| 2 green flashes | Someone pressed LAST ERROR and no codes are stored |
| 3 green flashes | Stored codes were just cleared |
You’ll only see 2 or 3 green after someone pressed the LAST ERROR button on the board. It plays back the last five faults, newest first, and only works when nothing is calling for heat or cooling. Holding it more than five seconds clears them (TM9E manual). It’s the fastest way for a tech to see what happened overnight when the furnace is running fine by morning.
Amber: running, or a warning
A slow amber flash means the thermostat is calling for heat and the furnace is running normally. On the two-stage TM9V, a continuous amber light means the flame signal is weak (TM9V manual). The modulating LP9C uses amber for more, from its installation manual:
Swipe to see all columns →
Swipe to see all columns →
| Light | What it means on an LP9C |
|---|---|
| 1 amber | Cooling |
| 2 amber | Heating, normal |
| 4 amber | Turned itself down for an airflow restriction: filter, closed vents |
| 5 amber | Turned itself down for a blocked vent or a clogged condensate drain |
| 6 amber | Heat pump heating, on a dual fuel system |
| Rapid amber | Flame sensor reading low |
4, 5 and rapid amber are warnings. The furnace keeps heating at a lower rate, as low as 35 percent, before it shuts off. That’s the time to change the filter, check the pipes outside and look at the drain, before it becomes a red code on the coldest night of the week.
Red: count it
Red flashes come in a group, then a pause, then the group again. This chart is from the TM9E installation manual for the single-stage furnaces in the family; the two-stage TM9V adds 12 red (model plug loose) and 13 red (high fire pressure switch) and times its limit codes a little differently (TM9V manual).
Swipe to see all columns →
Swipe to see all columns →
| Light | What it means |
|---|---|
| 1 red | Flame sensed with no call for heat. Shut off the gas |
| 2 red | Pressure switch closed when it should be open |
| 3 red | Pressure switch open when it should be closed: inducer, vent, hose or switch |
| 4 red | Main limit opened: the furnace overheated, filter first |
| 5 red | Rollout switch opened; it resets by hand, and it needs a tech |
| 6 red | Pressure switch opened four times in one call; locks out for an hour |
| 7 red | No flame after three tries; locks out for an hour |
| 8 red | Flame lost five times in one call; locks out for an hour |
| 9 red | Power polarity, ground or transformer wires reversed |
| 10 red | Gas valve powered with no call for heat. Shut off the gas |
| 11 red | Main limit open more than five minutes, usually the blower motor or wheel |
| Steady on, any color | The control board failed |
On the modulating LP9C a few counts differ: 4 red also covers a temperature sensor or the 24 volt fuse, 5 red covers the rollout switch or the condensate pressure switch, 6 red is the board losing touch with the gas valve, 10 red a shorted gas valve, 11 red the blower and 12 red the model plug (LP9C manual).
The three red codes you’re most likely to see
3 red flashes: the pressure switch
What you notice: The inducer at the top spins up, but nothing lights.
What causes it: The switch that proves the vent is clear never closed. A blocked PVC pipe outside, a backed up condensate drain, a split hose on the switch, a weak inducer or the switch itself.
What you can do: Clear the pipes where they leave the house, check the drain trap for standing water, power cycle once.
When to call us: If it comes back. The pressure switch guide walks every cause, and it applies to a Luxaire switch the same way.
7 red flashes: no flame after three tries
What you notice: Clicking and a glowing igniter, then nothing, then an hour of quiet.
What causes it: The gas, the igniter, the gas valve or, most often, a flame sensor too dirty to prove the flame.
What you can do: Check that the gas handle beside the furnace is in line with the pipe, then power cycle once.
When to call us: If it locks out again the same day.
4 red flashes: overheated
What you notice: The burners shut off while the blower keeps going, so the air turns cool.
What causes it: The limit switch opened. A clogged filter, closed vents, undersized ductwork or a weak blower motor. If it stays open more than five minutes it becomes 11 red.
What you can do: Put in a fresh filter and open every vent and return.
When to call us: If it trips again with the new filter. The blower is the same part York uses: York furnace blower motor.
Codes that mean stop
1 red and 10 red both mean gas may be flowing when nothing’s calling for heat. Turn the furnace off at its switch and close the gas valve by turning the handle across the pipe. If you smell gas, don’t touch any switches: leave the house and call your gas company from outside. If the CO alarm is going off, get everyone out and read what to do when the CO alarm goes off. 5 red is the rollout switch: flame came out of the burner box. Don’t reset it yourself; something pushed that flame out.
The flame sensor numbers
A weak flame signal is behind a lot of Luxaire calls, 7 and 8 red included. The manuals give the numbers a tech reads with a meter: about 3.7 microamps is normal, 1.5 is where the warning starts (continuous amber on the TM9V, rapid amber on the LP9C), and at 0.1 the furnace shuts the gas off (TM9V manual). Cleaning the sensor usually brings it back; the flame sensor guide shows what that involves.
Luxaire heat pumps (HL19B)
The Luxaire HL19B heat pump is the twin of Coleman’s HC19B and York’s YZT, with a two-digit display on the outdoor unit’s board: 01 to 04 are the high and low pressure switches, 06 and 07 low control voltage, 09 the outdoor sensor (YZT manual). The full list is in our Coleman furnace codes guide. Leave that panel on; there’s line voltage behind it.
How to reset a Luxaire furnace
Set the thermostat to off. Turn off the breaker or the switch for the equipment, wait about five minutes, turn it back on and set the thermostat back. Do it once. That clears the one-hour lockouts. If the same count comes back, the reset has done its job by telling you a part is failing. A steady light after a power cycle means the control board.
Luxaire, York, Coleman and Bosch
Luxaire is one of the names on the same furnaces York and Coleman sell: the owner’s manual and the modulating furnace’s installation manual are published under all three, and a 2001 safety recall covered furnaces under all three names. Bosch has run the home heating and cooling business behind York since July 31, 2025 (Bosch announcement), using the York name under a long-term license from Johnson Controls. Bosch lists Coleman and Luxaire as its regional brands.
More furnace codes
The same family: York furnace codes and Coleman furnace codes. Other brands: Carrier, Goodman and American Standard, or every brand in our error codes and warning lights guide. By symptom: a furnace blinking light and a furnace that won’t turn on. Our York repair page has what usually breaks in this family and what we charge.
Book a Luxaire repair
Call (703) 997-9757 or book online. A diagnostic visit is $99, and the tech reads the code, finds the part that set it and gives you the price before any work starts. We answer day or night. Our heating check is $67 per system, through December 31: furnace, heat pump or boiler. If someone already quoted you a new system, our free second opinion looks at it first. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
What does a flashing amber light mean on a Luxaire furnace?
A slow amber flash is normal: the thermostat is calling and it’s heating. On a modulating LP9C, 4 or 5 amber flashes or a rapid amber flash are warnings that it turned itself down for airflow, the vent or drain, or a weak flame sensor.
What does 3 red flashes mean on a Luxaire furnace?
The pressure switch never closed, so it won’t light. Check the PVC pipes outside and the condensate drain, then power cycle once.
What does a steady light mean on a Luxaire furnace?
A light that stays on without flashing means the control board failed. If it’s still steady after a power cycle, the board needs replacing.
How do I reset a Luxaire furnace?
Set the thermostat to off, turn off the furnace switch or breaker for about five minutes, then turn it back on. Do it once. If the code comes back, a part is failing.
Who makes Luxaire furnaces?
Luxaire comes from the same company as York and Coleman. Bosch has run that business since 2025, uses the York name under license and lists Coleman and Luxaire as its regional brands.
