How House Works

Goodman furnace code IdL: idle on the display, not an error

By How House Works EditorialBased on Goodman service manuals and installation instructionsChecked against sources Updated

Furnace control display or LED

IdL

“Normal operation”

Printed on 18 model series · 17 documents

GR9S92 / GR9S96 / GD9S96, A/GR9S96*U* Ultra-Low NOx, GR9S80 / GD9S80 / AR9S80 / AD9S80, A/GR9S80*U* Ultra-Low NOx, VR9S80/VD9S80, GR9T96 / GD9T96 / AR9T96 / AD9T96, GR9T80 / GD9T80 / AR9T80 / AD9T80, GRVT80 / GDVT80 / ARVT80 / ADVT80, GM9S92 / GM9S96 / GC9S96, GM9S80 / GC9S80 / AM9S80 / AC9S80 / VM9S80 / VC9S80, GM9C96 / GC9C96 / AM9C96 / AC9C96, GM9C80 / GC9C80 / AM9C80 / AC9C80, GMVC96*BB / GCVC96*BB, GMVC96*BA, GMVC80*AC / GCVC80*AC / ACVC80*AC / AMVC80*AC, GMVC8 / AMVC8 / ADVC8; ACVC8 / GCVC8, GMVM97*BA / GCVM97, *MVS80*U ; CCVS80; *MVS96; CCVS96 · IOG-2037A p. 41; RS6612302 p. 31; RS6621301 p. 34; RS6621302 p. 28; RS6612304 p. 27; RS6621304 p. 35; RS6621305 p. 43; IOG-2029D p. 39; IOG-2030B p. 28; IOG-2027E p. 46; IOG-2026B p. 30; IOG-2015L p. 45; RS6612014R3 p. 60; IOG-2023E p. 30; IOG-2016A p. 35; IOG-2017H p. 44; IOG-2033A p. 29

Owner can check

What it means

IdL is not a fault. Goodman’s tables call it “Normal operation” or “Idle” and give no corrective action IOG-2037A, p. 41; IOG-2037D, p. 43. The control’s mode table lists IdL for Idle, next to FAn for continuous fan, 1AC and 2AC for low and high stage cooling, and gH for gas heat RS6612301, p. 35.

The first character is the letter I, not the number 1. Goodman’s documents print IdL, sometimes spaced as “I dL”; none of them prints 1DL. Searches for “goodman furnace code 1dl” (Google autocomplete, checked October 19, 2026) most likely mean this display.

On the Ultra-Low NOx GR9S96U and GR9S80U two more displays are normal: 888, with all segments lit, means the control is powering up, and the menu writes the idle state as Idl, “Control in Idle stage” RS6612302, p. 11; RS6621302, p. 10.

Check these first

IdL with a cold house means the control is idle and no code is showing. The owner’s manual has a checklist for a furnace that is not operating; since no code is flashing, it goes straight on to these checks, in this order HIG-2002A, p. 8:

  1. Check that the thermostat is set to HEAT and its temperature setting is above room temperature HIG-2002A, p. 8.
  2. Check the electrical panel for tripped circuit breakers or failed fuses, and reset the breakers or replace the fuses HIG-2002A, p. 8.
  3. Check for dirty filters, and replace or clean them. Disconnect electrical power before removing filters HIG-2002A, p. 7. The manual says to check them at least once a month HIG-2002A, p. 8 and never to run the furnace without one HIG-2002A, p. 7.
  4. Check that return air and supply air grilles are not blocked by furniture, drapery, clothes or carpeting, and clear them HIG-2002A, p. 8.
  5. On high efficiency furnaces, check that the intake and vent terminations are not blocked HIG-2002A, p. 8.

If these checks do not solve the problem, the manual says to contact a qualified servicer, and not to troubleshoot beyond these points or attempt repairs yourself HIG-2002A, p. 8. Do not remove any internal compartment covers HIG-2002A, p. 6.

When to call a licensed technician

  • The checklist did not bring the heat back HIG-2002A, p. 8.
  • The display gives no signal. The GR9S96 service manual lists that symptom with no 115 volt power to the furnace or no 24 volt power to the control RS6612301, p. 37. The current instructions call the row nonE, with no 120 VAC power to the furnace or no 24 volt power to the control, and list its causes: a blown fuse or tripped circuit breaker, a manual disconnect switch turned OFF, an open door switch, a loose or misconnected 24 volt wire, a furnace electrical supply shared with other devices, and a control that does not work IOG-2037D, p. 43. The breaker is on the owner’s checklist HIG-2002A, p. 8; the voltage checks and wiring repairs in that row are technician work IOG-2037D, p. 43.
  • A code replaces IdL. Find it in the table of Goodman codes.

Notes for different models

Board or series Normal display Meaning in the document Source
Most three-character boards IdL “Normal operation” IOG-2037A, p. 41; RS6612014R3, p. 60
2026 installation instructions and the GMVC96*BB, GM9C80 revisions of 2026 IdL “Idle” IOG-2037D, p. 43; RS6612023R2, p. 40
Ultra-Low NOx GR9S96U, GR9S80U (menu) 888, then Idl “All segments illuminated = control powering up”; “Control in Idle stage” RS6612302, p. 11; RS6621302, p. 10
Single-LED boards (GMSS9, GMES9 and others) LED steady on “Normal Operation” RS6612012R8, p. 44
GMEC96, GMEC80 Green solid on “Furnace is not receiving a call” IOG-2011U, p. 54 (GMEC96); RS6621005R1, p. 28 (GMEC80)
MES96U, GMES80*U, 2019 manuals Green steady on “Normal operation, idle/ standby.” RS6612017, p. 21
Older ComfortNet boards OP or On Displayed while awaiting a call from the thermostat: OP on PCBKF101 boards, ON on PCBKF102 and 103 RS6612002, p. 48

Related Goodman codes

  • nonE “No 120VAC power to furnace or no 24 volt power to integrated control module.”
  • LED steady on “Normal Operation”
  • Green solid on “Furnace is not receiving a call”

See also

Other gas furnaces: Carrier, Lennox, Rheem and Ruud

All Goodman codes

Goodman is a trademark of its owner. How House Works is not affiliated with or endorsed by Goodman.

Sources

  1. Goodman Manufacturing. Gas-Fired Warm Air Furnace User's Information Manual. HIG-2002A, 09/19. Accessed Oct 17, 2026.
  2. Goodman Manufacturing. Gas-Fired Warm Air Furnace User's Information Manual. HIG-2002, 07/19. Accessed Oct 17, 2026.
  3. Goodman Manufacturing. Service manual: GMVC9, GCVC9, AMVC9, ACVC9 Gas Furnaces & Accessories. RS6612002, February 2013. Accessed Oct 17, 2026.
  4. Goodman Manufacturing. Installation Instructions for *R9S96/*D9S96 & *R9S92 Single-Stage Gas Furnace. IOG-2037D, 10/2026. Accessed Oct 17, 2026.
  5. Goodman Manufacturing. Service manual: 34.5" Chassis ACVC96*BB/AMVC96*BB/GCVC96*BB/GMVC96*BB Gas Furnaces. RS6612023R2, November 2026. Accessed Oct 19, 2026.
  6. Goodman Manufacturing. Service manual: 34.5" Chassis ACVC96*BA/AMVC96*BA GCVC96*BA/GMVC96*BA Gas Furnaces (BA revision & above). RS6612014R3, October 2020. Accessed Oct 19, 2026.
  7. Goodman Manufacturing. Installation Instructions for *R9S96/*D9S96 & *R9S92 Single-Stage Gas Furnace. IOG-2037A, 09/2023. Accessed Oct 17, 2026.
  8. Goodman Manufacturing. Service manual: 96% Single Stage Ultra-Low NOx Gas Furnaces A/GR9S96*U*. RS6612302, January 2025. Accessed Oct 17, 2026.
  9. Goodman Manufacturing. Service manual: 80% Single Stage Ultra-Low NOx Gas Furnaces A/GR9S80*U*. RS6621302, October 2024. Accessed Oct 17, 2026.
  10. Goodman Manufacturing. Service manual: GR9S92 / GR9S96 / GD9S96 / AR9S92 / AR9S96 / AD9S96 / VM9S96 / VC9S96 Single Stage Gas Furnaces and Accessories. RS6612301, May 2024. Accessed Oct 17, 2026.
  11. Goodman Manufacturing. Service manual: Goodman Brand GR9T96/GD9T96 & Amana Brand AR9T96/AD9T96 Two Stage Furnace with Nine speed ECM Motor. RS6612304, May 2024. Accessed Oct 17, 2026.
  12. Goodman Manufacturing. Service manual: Goodman Brand GR9T80/GD9T80 & Amana Brand AR9T80/AD9T80 Two Stage Furnace with Nine Speed ECM Motor. RS6621304, December 2023. Accessed Oct 17, 2026.
  13. Goodman Manufacturing. Installation Instructions for *M9S96/*C9S96 & *M9S92 Single-Stage Gas Furnace. IOG-2029D, 07/2023. Accessed Oct 17, 2026.
  14. Goodman Manufacturing. Installation Instructions for *M9S80 & *C9S80* Gas Furnace. IOG-2030B, 04/2022. Accessed Oct 17, 2026.
  15. Goodman Manufacturing. Installation Instructions for *M9C96 & *C9C96 Two-Stage Gas Furnaces. IOG-2027E, 07/2023. Accessed Oct 17, 2026.
  16. Goodman Manufacturing. Installation Instructions for *M9C80 & *C9C80* Gas Furnace. IOG-2026B, 04/2022. Accessed Oct 17, 2026.
  17. Goodman Manufacturing. Installation Instructions for *CVC96*BB & *MVC96*BB Two-Stage Gas Furnace. IOG-2015L, 06/2023. Accessed Oct 19, 2026.
  18. Goodman Manufacturing. Installation Instructions for *MVC8*CA & *CVC8*CA Gas Furnace. IOG-2016A, 07/2019. Accessed Oct 17, 2026.
  19. Goodman Manufacturing. Installation Instructions for *CVM97*B* & *MVM97*B* Modulating Gas Furnace. IOG-2017H, 07/2023. Accessed Oct 19, 2026.
  20. Goodman Manufacturing. Service manual: Goodman Brand GRVT80/GDVT80 & Amana Brand ARVT80/ADVT80 80% Two Stage Gas Furnaces with Variable-Speed ECM Motor. RS6621305, January 2025. Accessed Oct 17, 2026.
  21. Goodman Manufacturing. Installation Instructions for *MVC80* & *CVC80* Gas Furnace. IOG-2023E, 07/2022. Accessed Oct 17, 2026.
  22. Goodman Manufacturing. Installation Instructions for Gas Variable Speed Furnace. IOG-2033A, 05/2023. Accessed Oct 17, 2026.
  23. Goodman Manufacturing. Service manual: 34.5" Chassis ACVC96*BA/AMVC96*BA GCVC96*BA/GMVC96*BA Gas Furnaces (BA revision & above). RS6612014, December 2017. Accessed Oct 17, 2026.
  24. Goodman Manufacturing. Service manual: 80% Single Stage Gas Furnaces GR9S80, AR9S80, GD9S80, AD9S80, VR9S80, VD9S80 & Accessories. RS6621301, November 2023. Accessed Oct 17, 2026.
  25. Goodman Manufacturing. Service manual: 34.5" Chassis ACVC96*BB/AMVC96*BB/GCVC96*BB/GMVC96*BB Gas Furnaces. RS6612023, January 2021. Accessed Oct 17, 2026.
  26. Goodman Manufacturing. Service manual: GMSS9*/GCSS9*/AMSS9*/ACSS9* Single Stage Gas Furnaces and Accessories. RS6612012, August 2014. Accessed Oct 17, 2026.
  27. Goodman Manufacturing. Service manual: GMSS9*/GCSS9*/AMSS9*/ACSS9* Single Stage Gas Furnaces and Accessories. RS6612012R8, December 2017. Accessed Oct 19, 2026.
  28. Goodman Manufacturing. Installation Instructions for *MEC96 Upflow / Horizontal Two-Stage Gas Furnace. IOG-2011U, 02/2022. Accessed Oct 19, 2026.
  29. Goodman Manufacturing. Service manual: Goodman Brand GMEC80/GCEC80 & Amana Brand AMEC80/ACEC80 Two Stage Furnace with multi-speed ECM Motor. RS6621005R1, June 2020. Accessed Oct 19, 2026.
  30. Goodman Manufacturing. Service manual: *MES96*U Single Stage Ultra-Low NOx Gas Furnaces and Accessories. RS6612017, October 2019. Accessed Oct 17, 2026.