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York TM9V two-stage variable-speed gas furnace · exact showing

York TM9V two-stage variable-speed gas furnace showing a steady-on

a steady-on LED in any color means Control failure. This answer applies only to TM9V*C two-stage variable-speed ECM gas furnaces (96% AFUE) whose control board LED flashes red, green or amber, as listed in York International's installation manual 5402851-UIM-A-0917. The slow flash is two seconds on and two seconds off. Other codes flash for a third of a second on and off, repeated the number of times of the code, with a two-second pause between sets, and they repeat as long as the fault lasts. Other furnace families use other pages.

On the covered York TM9V two-stage variable-speed gas furnace, a steady-on LED in any color means Control failure. First, turn power to the furnace off and back on, and note whether the LED comes back steady. Then: york's manual says that if the fault code returns after cycling the power, the control board must be replaced, and that the control board is not field-repairable.

Part of York TM9V two-stage variable-speed gas furnace error codes guide

Differential

Likely causes of “York TM9V two-stage variable-speed gas furnace showing a steady-on LED in any color”, and how to tell them apart

  1. 1

    A control board failure

    What separates it The LED stays on, in any color, and nothing runs

    How to confirm York names the steady LED as a control failure

  2. 2

    A power glitch

    What separates it The LED clears after a power cycle

    How to confirm Cycle the power once

  3. 3

    A loose connector

    What separates it The furnace was recently serviced

    How to confirm Technician inspection

  4. 4

    A surge or storm damage

    What separates it The code follows lightning or an outage

    How to confirm Technician inspection

  5. 5

    A failing power supply to the board

    What separates it The LED flickers

    How to confirm Technician testing

Before you touch a setting

Record this first — changing settings destroys the evidence

  • That the LED is steady, not flashing
  • The LED's color
  • Whether it follows a storm or an outage
  • Whether cycling the power changes it

Try in this order

0 of 8 completed

  1. What to do first

    Reversible

    Turn power to the furnace off and back on, and note whether the LED comes back steady.

  2. Correct only the documented fault domain

    Reversible

    York's manual says that if the fault code returns after cycling the power, the control board must be replaced, and that the control board is not field-repairable.

  3. Turn the furnace off

    Reversible

    At the switch.

  4. Wait one minute

    Reversible

    Then turn it on.

  5. Look at the LED

    Reversible

    Steady or flashing?

  6. If steady again

    Reversible

    Do not repeat more than once.

  7. Note the date

    Reversible

    And any storm.

  8. Call a technician

    Reversible

    The board needs replacing.

Model-specific

What is true of this model and not of its siblings

A different kind of signal
Most York codes are counted flashes. A steady light that does not flash is a different signal: the control itself has detected an internal fault and cannot run its program.
York's statement
York says that if the code returns after a power cycle, the control board must be replaced, and that the board is not field repairable.
Surge protection
A whole-house surge protector or a plug-in one for the furnace can reduce board failures, and a technician can fit one.
What a replacement involves
The technician swaps the board, moves the connectors and sets the model ID plug. The furnace is tested through a full cycle.
Warranty
Boards often have a parts warranty. Have the model and serial numbers ready.
Temporary heat
Use safe electric heaters while you wait, and never a gas oven.
Reading the light correctly
A control board shows its state with one LED. A steady light, not flashing, is a different message from any counted flash code. If the light is off, the board has no power and the cause may be a switch, a fuse or the transformer. If it is steady, the board has power but has stopped. Note which of these you see.
Protecting the new board
Boards are sensitive to surges and static. A surge protector built for HVAC equipment can reduce failures, and technicians will wear a wrist strap when handling a board. Ask them about it if boards have failed before.
Before you pay for a board
Ask the technician to confirm the board has failed by testing the 24 volt supply and the connections. A board that fails because of a short in a component will fail again if the short is not found. Ask whether the repair includes testing the parts the board drives.

Stop boundary

When this stops being a self-service repair

  • !Never bypass, jumper or tape over a safety switch
  • !Stop for a carbon monoxide alarm, soot, scorch marks or flame outside the burner compartment
  • !Call a qualified technician for anything behind the furnace's panels
  • !If you smell gas, leave the building and call the gas utility from outside; do not use switches or phones inside

Evidence ledger

Sources behind this answer

01
York International Two Stage Variable Speed ECM Residential Gas Furnaces installation manual, TM9V*C series (5402851-UIM-A-0917)
02
York York furnace diagnostic LED flash codes

Exact questions

Common questions

What does a steady-on LED in any color mean on a York TM9V two-stage variable-speed gas furnace?+

Control failure.

What does a steady LED mean on a York TM9V?+

A control failure.

Does the color matter?+

York says any color.

Can the board be repaired?+

York says it is not field repairable.

Will a power cycle fix it?+

If it does not return, it may.

Wrong device or version?

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