Trane does not publish one universal blink-code table for its furnaces. Its own guidance says the meaning of a light depends on the make and model and on the pattern: a slow green blink may just mean there is no call for heat, a faster green blink can mean the furnace is heating, and a blinking red light generally signals a problem. Some furnaces show error codes made of numbers and letters instead of lights.
Trane's advice is to write down exactly what you see, which color, which pattern and which code, and to call for service rather than open the furnace. On the S9V2-VS, Trane's installer's guide says the control has Active Errors and Last 6 Faults menu entries, and shows errors on the display alternating with the system mode. The meaning of any pattern must come from your unit's own legend.
What this covers
- Trane gas furnaces with an exterior light, a control-board LED, or a display that shows error codes
- Recording the color, pattern and any code accurately for the technician
- The general meanings Trane's own page gives for green, red and steady lights
What it does not cover
- ×American Standard or other brands' boards unless the furnace's own legend says so
- ×Removing the front panel while the furnace is running, or any repair
Try in this order
0 of 7 completedNote which kind of indicator you have
ReversibleTrane says depending on make, model and issue you may see a green light blinking continuously, a solid green or red light, a blinking red light, a solid amber or yellow light, or error codes made of numbers and letters. Some furnaces have an exterior light; on others the light is on the control board behind the front panel.
Read the general meaning of green
ReversibleTrane says a green light blinking is not necessarily bad. A slow blink may mean there is simply no call for heat, and a faster continuous blink can mean the furnace is in active heating mode. It varies by make and model, so check your unit's legend.
Treat red as a problem to record
ReversibleTrane says a blinking red light on the furnace or the control board generally signals a problem. Pay attention to the pattern and write it down: a steady blinking red light, two blinks and a pause, or three blinks and a pause that repeats. Each sequence means something different.
Capture the pattern accurately
ReversibleFilm two complete repetitions with your phone, or write down the number of flashes, the pause, and the color. Also photograph the model and serial number label. Trane says to tell the person booking the visit what lights or error codes you saw and the furnace brand and model, so the technician arrives with the right parts.
Know what the fault menu can show on an S9V2-VS
ReversibleTrane's installer's guide for the S9V2-VS describes a control menu with Status, Active Errors and Last 6 Faults entries. On the display, an error appears as an E-code alternating with the system mode and airflow request, and the guide's examples include a 1st stage pressure switch error, a 2nd stage pressure switch error and an open limit switch error. Clearing stored faults is a technician procedure.
Handle a lockout the right way
ReversibleIf the furnace shuts down and will not restart, see this site's furnace lockout page. Trane says a hard lockout needs a technician to resolve the cause and reset the furnace, and that changing the filter is the only thing to try yourself.
Keep the maintenance basics current
ReversibleTrane says changing standard filters every 30 to 90 days prevents many problems and recommends a yearly furnace tune-up. A dirty filter can cause overheating shutdowns and lockouts.
Evidence ledger
Sources behind this answer
Where the manufacturer's article stops. Trane's page on blinking furnace lights and its S9V2-VS installer's guide were read in full for this page. Neither prints a complete flash-code table. Repair-company blogs and forum answers do publish tables, but none could be checked against a Trane document, so none is reproduced here.
Trane's own page on furnace lights: colors and patterns, what to record, and to call for service. It publishes no code table.
Trane's installer's guide for the S9V2-VS. Its control menu has Active Errors and Last 6 Faults entries and shows examples such as a 1st or 2nd stage pressure switch error and an open limit switch error. It prints no complete code table.
Trane's own guide: soft lockout versus hard lockout, the common causes, that changing the filter is the only thing to try yourself, and what a technician checks.
Exact questions
Common questions about “How to read a blinking light on a Trane furnace”
Is there a Trane blink-code chart I can trust?+
Charts on blogs and forums could not be checked against a Trane document, so use the legend on your furnace or ask a Trane dealer.
Does a blinking green light mean the furnace is broken?+
Not necessarily. Trane says a slow green blink may mean no call for heat and a faster blink may mean it is heating. It depends on the model.
What should I do when the light is blinking red?+
Write down the pattern, note the model, and call for service. Trane says a red blink generally signals a problem and not to try to fix the furnace yourself.
Can I clear the fault memory myself?+
The S9V2-VS installer's guide describes clearing the Last 6 Faults by holding the OPTION key in the fault menu. That is a technician procedure, and clearing it removes the record your technician needs.
How do I read a Trane furnace light?+
Most Trane furnaces have an LED visible through the blower door that flashes a number of times per cycle. The count matches a table on the inside of the door.
Is a steady light bad?+
A steady light generally shows normal operation on many boards, while flashes point to a fault. Check your model's label.
Should I keep resetting it?+
No. Repeated resets can hide the cause. Note the code and, if it repeats, contact a technician.