Carrier · Status code
Carrier 59SC6A status code 27: super plug or control program fault
Major code 27 is shown when the control detects a problem with the program source used to load or verify its model program. The service label's instructions walk through the super-plug remedy: remove it and retry (27.1), try a different super plug (27.2), and replace the control if it still fails (27.3).
On the control
- Code
- 27
- Minor
- 27.1 · 27.2 · 27.3
- Door LED
- 2 short flashes then 7 long
- Controller
- 59SC6A integrated furnace control with 3-digit LCD display and door LED
- Applies to
- Carrier Comfort 96 (59SC6A)
- Manual
- 59SC6A-01SI REV D
What each minor code says, verbatim
| Display | Manufacturer wording |
|---|---|
| 27.1 | Program in super plug is missing, not recognized, or corrupted. Remove super plug then retry. |
| 27.2 | If still have 27 code, try a different super plug. |
| 27.3 | If still fails, replace control. |
A code is a condition, not a diagnosis
This is a service-tool code: it tells the technician the program source or the control is at fault, not which one until the steps are tried. On an untouched furnace, the control itself should be checked against the rating-plate program.
Which furnaces this applies to
Documented for Carrier 59SC6A Comfort 96 furnaces in installation instructions 59SC6A-01SI REV D. The super plug carries the model program used to program replacement control boards; the rating plate identifies the correct program number.
Scope: Carrier 59SC6A Comfort 96 furnaces with the on-board 3-digit display control. Not sure which control you have? Send us the full model number from the rating plate.
Safe things to look at first
- Read the full code on the control display through the door, including any minor digit (for example 33.2), and write it down.
- Look, without touching, for obvious conditions you can report: snow or ice at the vent terminations, water on the floor, a loaded filter, a condensate pump that is full or off.
- Note whether the furnace still heats at all, and how long it runs before the code returns.
- Note whether any service work or programming happened shortly before the code appeared, and read the program number from the rating plate.
Do not
- Do not bypass or jumper the door switch, limit switches, rollout switches or pressure switches.
- Do not open the burner compartment, disconnect tubing, or adjust the gas valve or gas pressure.
- Do not keep cycling power to force the furnace to relight; repeated resets hide the fault and can allow unburned gas to build up after ignition failures. If the code returns, stop and call.
What a technician does
- A technician follows the service-label sequence: remove the super plug and retry, try a different super plug, and replace the control only if the fault persists, programming it with the rating-plate model program.
Related components and symptoms
Questions people ask
My furnace was never programmed with a super plug. Why does 27 show?
If no one has serviced the control recently, the fault is inside the control or its stored program. A technician compares the stored program with the rating plate and reprograms or replaces the control.
Seeing code 27 on your Carrier?
Tell us the full code, the model number and whether the furnace still heats on low. BC Wide prioritizes no-heat calls across Greater Vancouver.