Solid Red Light On Furnace Circuit Board [Solved]

Is your Furnace not working and you have noticed a solid red light on your furnace? We have got you covered!

A solid red light on the furnace circuit control board means it has power and is waiting on call for heat. This is a normal operation on a carrier or Goodman Furnace and there is nothing alarming to it.

However, if you have a flashing red light, that could mean an error code that you’ll have to decode by referencing the error code chart which is typically located at the back of the protective panel.

If you don’t have a code error chart, use the chart we have provided in this guide. Each make will have different meanings.

For a Goodman Furnace, see our guide here

Jump R to W on the furnace board with a paperclip or needle nose pliers and hold the door switch in to see if it will come on.

Why Furnace Has Solid Red Light On A Circuit Board But Not Working

As I mentioned earlier in this, if your furnace is not working and has a solid red light on its control board, that technically means the furnace control board is Ok.

But what would prevent your furnace from working in this case? It can only be a wiring issue or problems with the thermostat.

Let’s look at how you can troubleshoot this problem in a bit more details.

Broken/ Bad wiring

You can start the troubleshooting process by going to the thermostat and putting your thermostat into heat mode.

Then observe if the lights blink on the circuit control board.

Ensure that you tip in the door switch otherwise you won’t have power to your furnace.

If the furnace doesn’t kick on and you can only see a steady red light then try jumpering the R and W terminal on the furnace terminal block. You can use a paperclip for this task.

If the furnace kicks on, Now jumper the R and W wires at the thermostat.

Bad thermostat

A Bad thermostat could be a reason why there is a solid red light on the furnace circuit Board and the furnace is not working. A thermostat regulates the temperature by sending heating instructions to the furnace control board when the temperature falls below a set point.

But when a thermostat is bad or malfunctioned, it wont send any heating instructions to the circuit control. If you have a bad thermostat, it’s always best to get a replacement.

Carrier Furnace Error Codes (Flashing Lights Meaning)

LED Code	Status
12	NO PREVIOUS CODE – Stored status codes are erased when power(115VAC or 24VAC) to control is interrupted or 48 hours after each fault is cleared
12	BLOWER ON AFTER POWER UP (115VAC or 24 VAC) – Blower runs for 90 seconds,if unit is powered up during a call for heat (R-W closed).
13	LIMIT OR FLAME ROLL-OUT SWITCH LOCKOUT – Control will auto reset after threehours. Reset switch or replace fuse link.
14	IGNITION LOCKOUT – Control will auto-reset after three hours.
21	GAS HEATING LOCKOUT – Control will NOT auto-reset.Check for: – Mis-wired gas valve – Defective control (valve relay)
22	ABNORMAL FLAME-PROVING SIGNAL – Flame is proved while gas valve isde-energized. Inducer will run until fault is cleared.Check for: – Leaky gas valve – Stuck-open gas valve
23	PRESSURE SWITCH DID NOT OPEN Check for:- Obstructed pressure tubing – Pressure switch stuck closed
24	SECONDARY VOLTAGE FUSE IS OPENCheck for: – Short-circuit in secondary voltage (24VAC) wiring
31	HIGH-HEAT PRESSURE SWITCH OR RELAY DID NOT CLOSE OR REOPENEDCheck for: – Control relay may be defective
32	LOW HEAT PRESSURE, DRAFT SAFEGUARD, AUX-LIMIT (when used) SWITCH DID NOTCLOSE OR REOPENED (DOWNFLOW ONLY) If open longer than five minutes,inducer shuts off for 15 minutes before retry. Check for:- Proper vent sizing – Low inducer voltage (115VAC)- Defective Blower motor or capacitor – Defective inducer motor- Defective pressure switch – Restricted vent- Inadequate combustion air supply – Excessive wind- Disconnected or obstructed pressure tubing If it opens after trial for ignitionperiod, blower will come on for 90 second recycle delay

Final thoughts

In summary, a red light on a furnace circuit board is typically a normal operation and indicates that the control board is receiving power and is ready to receive heating instructions from the thermostat.

We hope this guide has helped you to find a solution to a thermostat that is not working. If for any reason your Furnace is still not working, perhaps consider calling in local HVAC professionals for help.

More resources: https://www.shareddocs.com/hvac/docs/1009/Public/02/58-3T.pdf