# Error code 12 problem on my Carrier 58RAV



## analog414

*I have a "blower on after startup (115v or 24v)" error 12 going on. When I shut down the power for 15 minutes and restart. The unit right away starts the blower and thats it! No attempt to ignite at all. The blower just blows colds air and does not stop. Any suggestions on this would be great. I just need a fishing pole. Thanks Rick*


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## yuri

That is normal. let it blow for 90 seconds which is what that is designed for. If it is calling for heat when you turn power on/off that is what it is supposed to do. That cycle should stop and then try to start the burner. Check for error code after that.


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## beenthere

Yep. 90 seconds everytime its powered up while its receiving a call for heat. It will do that.


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## analog414

*I should have added that this problem went on all day long. Cold air for 10 hours. No heat. 58 degrees. I tried to shut off the power just to see if anything new would happen.*


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## beenthere

Don't shut the power off. Leave it run for 90 seconds, and see what other code it gives.


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## yuri

Probably an open or blown limit control. Check for an auxiliary one mounted on the fan housing (counterflow furnace) with a manual red reset button. Clean your air filters and makes sure all vents are clean and open.


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## analog414

*Interesting. Blower ran 90 seconds. Then code 33 starting blinking. Then the glow stick lit and flames. But that only lasted 3 minutes as the flames went out and it blinked 33 again. But a minute or so later the glow stick started and flames. This went on maybe 5 minutes and then cycled all over again. I did change the filter. It was dirty but it has been worst before. It appears that I have heat. Never looked at the furnace in action before. I assume it never cycled back to heat hence the 58 degrees when i got home. Maybe and hopefully it was just the filter. Thanks so much for the replies. *


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## Houston204

If the problem persists you should examine the inlet side of your evaporator coil.


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## Houston204

Especially if the filter was fiberglass.


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## mikecampbell97

*Carrier Furnace Code 12*

My Carrier from 2004 recently started giving me the code 12 error. The furnace would start (flames light up), run for about 45-60 seconds and then as soon as the blower came on, the furnace would stop. Eventually it didn't even get that far before it started to short cycle. I tried replacing the flame ignitor and cleaning the flame sensor and had an HVAC come out and tell me it was likely the circuit board. A new board cost $400 (just the circuit board w/ no guarantee that was the issue), so I seriously debated trying that or just going with , but I bought the board, put it in and so far so good. Just wanted to post this because I wasn't able to find too much online about the code 12 error having to do with the circuit board.


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## yuri

Code 12 means if the thermostat was calling for heat and you interupted the 120 volts to the furnace it will start the fan. It thinks the furnace has been running and is hot and you had a power failure and it needs to cool off to prevent damage.

Code 21 is a gas heating lockout. 

LOTS of people read the code wrong as the short and long flashes are close in length.


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## awol_OK

Very similar problem. Carrier model 58 DLA has high pitch noise coming from fan motor. might be a bearing. Looked at the LED code flashing was 33. But I could tap the motor housing end and get the fan moving. SO I started the furnace, gas came on, ignitor ignited, then the fan tried to move. Kept tapping the motor end and moving the cage by hand but not starting to turn this time. Turns pretty freely for a cage fan and motor attached. Anyway by this time the furnace overheated as expected and shut down due to no supply air from the non-functioning fan. NOW my LED code is 12 twelve. have checked it three times, one short, two long flashes. im not sure what needs to be reset. Will check the capacitor next, then the voltage from the board to the fan motor, before I try to replace the fan motor.

Any suggestions about the code 12?


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## beenthere

Its a fan pre run code. The control board has a heat call from the thermostat when power is turned. It runs the blower first. And gives that code to let you know.


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## awol_OK

And as a follow-up, I put the unit in fan-run mode with the heat off. So no call for hEAT. when the relay tripped to send power to the fan, I spun the cage by hand and the fan started full speed. this means the motor is fine and the capacitor needs replacing. but I tried the same steps with adding heat. ignitor starts, gas flows, heats up the blades, but I cannot start the motor by hand the same way, by spinning the fan cage by hand.

Can the motor be just on the verge of complete failure? or is there a power drain or power limit that could occur when the full heat system is used?


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## beenthere

Does your control board have a heat fan speed terminal and a cooling fan speed terminal. If so, it may be that the heating speed winding of the motor is going out. Or the heating speed of the blower is too low in HP to be able to run with a weak capacitor.


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## beenthere

For a quick way to get some heat in the house. Set thermostat to fan on, Get the blower started, quickly put door on so blower doesn't stop spinning. Turn heat on at thermostat. Get new capacitor this morning when places open up.

Don't want teh blower to operate too long like that, or you will need another motor.


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## supers05

There's a chance that the low speed could be fried..... 

As BT mentioned, changed. Change the cap asap and recheck. 

They do have thermal overloads built into the motor, so if they usually only like to try to start like that once or twice before tripping. Especially true for down flow or horizontal units. 

Cheers!


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## awol_OK

Thanks for the feedback. I was able to turn the blower cage by hand so I didn't think the motor was seized. But after I disassembled the motor from the cage, I could barely turn the motor shaft. Bought new motor and capacitor, install Sat morning and all working . Was hoping it was the capacitor only, but once I got the cage and motor separated, it was definitely the motor. Pretty awesome the folks who designed the LED blinking system.


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