no heat. carrier code 13 - DIY Chatroom

lnlnln · 02-02-2009, 05:43 PM

My home has a Carrier gas furnace. It stopped working recently. I have checked for a code and received 13? With the covers off and the interlock switch pressed, this is what the system is doing: 1. thermostat calls for heat 2. draft inducer turns on (I see the inducer rotating) 3. hot surface ignitor glows bright yellow 4. gas valve opens 5. burners ignite and work for about 3 minutes 6. Blower does not start, 7. after about 3 min the system turns off completely and I see code 13 (limit switch lockout).
Sometimes blower does start and everything works fine, however, if it is not, I smell like something is burning coming out to the house, not terribly strong smell, but one can smell it.
Appreciate any help.

HvacWiz · 02-02-2009, 06:57 PM

You either have a bad blower motor or a bad circuit board. if you have a volt meter check to see if you have power to motor after furnace fires.

lnlnln · 02-02-2009, 09:16 PM

Thank you.
I am able to start the blower sometimes. I open the cover and supply the voltage. After the call, hot surface ignitor glows, gas valve opens and burners ignite, but blower does not start and in 160 seconds burners stop working. I release the interlock switch and press it again. Blower motor starts. It runs for couple of minutes and stops. At that time the hot surface ignitor starts glowing again, gas valves open and burners ignite, in about 150 sec blower motor starts working and everything is fine: for 5-10 hours. After that blower motor will not start automatically. I need to repeat everything again.
I can measure the voltage. Should I measure it only to motor or somewhere else (circuit board, etc.)? How to check whether the circuit board is operational?
Thank you.

yuri · 02-02-2009, 09:52 PM

What is the model and serial # of the furnace. Sounds like your circuit board is faulty. When you interrupt the power and turn it on the fan runs as the board does a self test/power failure scenario. That tells me the motor is okay. Sounds like your board and the built in fan relay are failing.

HvacWiz · 02-02-2009, 10:38 PM

Like yuri said, sounds like you have a bad board. If you turn your fan to the "on" position on your stat you might be able to get by until you get a new board.

lnlnln · 02-02-2009, 10:45 PM

Thank you.

Carrier model CK5BXA036017AAAA
serial number 4000X12918

How can I check to make sure the board is faulty? Is any specific test to check it?

Thank you.