Trane XB80 furnace no heat, blower still working

[slycer2002]

Good evening. I just found this great-looking site and I'm hoping someone out there can help me. Last night our Trane XB80 lost its heat. Usually when the furnace is working correctly, there is that pre-ignition fan that runs and clears the combustion chamber, and then the burners ignite and the whole thing takes off. Right now, with our current issue, this doesn't happen. The main blower starts up right away and just blows cold air. After doing some research, I figured it was either the ignitor or we had a clog in the condensate drain. I managed to dig out our user's manual for the furnace, and it said that with no heat and a working blower, the problem would be a clogged condensate drain. I hooked a wet/dry vac up to the drain outlet and turned it on, but got nothing. I removed the panel around where the outlet pipe attaches to the furnace so I could find the other end of the drain (which was bone dry) and with my finger over that hole, turned the vacuum on. I had good suction at that end, so I have ruled out a clog. This leaves me with a bad ignitor. From what I have read, these have a life expectancy of 3-5 years which would put ours close to the outside of that range. During my research on the Internet, I also found some info about the LED light that could flash error codes. When I pushed the switch back in with the panel off, all the light did was blink about once a second with no variation. Am I right to believe that we could have a bad ignitor? Any ideas? I have also seen some talk about a rollout switch or sensor attached to some issues similar to mine. Where is this part and how would I check it? Its about to be a chilly night, and I want to keep them to a minimum! Thank you in advance for any help. BTW, the specific model number is TUE080A936L3, and its about 5 years old. Thanks again!

[slycer2002]

I have some LED codes for you...

I managed to get my wife to help me long enough to get some LED codes for you. When it gets a call for heat, the LED blinks four times, pauses, blinks four times, pauses, etc. According to the label on the door, this is an open limit switch. Is there a way to reset this? I have cycled power on the furnace numerous times, and it keeps restarting with this same problem. Would it help if I unplugged the switch and then plugged it back in? Thank you in advance for any help again.

[slycer2002]

The problem has been solved

This morning I jumpered across the limit switch, and damned if the furnace didn't fire right up. So, looks like I'll be replacing the limit switch today. Oh, well. It could have been worse, and we'll have heat tonight! Last night was COLD!!!

[paul52446m]

Good evening. I just found this great-looking site and I'm hoping someone out there can help me. Last night our Trane XB80 lost its heat. Usually when the furnace is working correctly, there is that pre-ignition fan that runs and clears the combustion chamber, and then the burners ignite and the whole thing takes off. Right now, with our current issue, this doesn't happen. The main blower starts up right away and just blows cold air. After doing some research, I figured it was either the ignitor or we had a clog in the condensate drain. I managed to dig out our user's manual for the furnace, and it said that with no heat and a working blower, the problem would be a clogged condensate drain. I hooked a wet/dry vac up to the drain outlet and turned it on, but got nothing. I removed the panel around where the outlet pipe attaches to the furnace so I could find the other end of the drain (which was bone dry) and with my finger over that hole, turned the vacuum on. I had good suction at that end, so I have ruled out a clog. This leaves me with a bad ignitor. From what I have read, these have a life expectancy of 3-5 years which would put ours close to the outside of that range. During my research on the Internet, I also found some info about the LED light that could flash error codes. When I pushed the switch back in with the panel off, all the light did was blink about once a second with no variation. Am I right to believe that we could have a bad ignitor? Any ideas? I have also seen some talk about a rollout switch or sensor attached to some issues similar to mine. Where is this part and how would I check it? Its about to be a chilly night, and I want to keep them to a minimum! Thank you in advance for any help. BTW, the specific model number is TUE080A936L3, and its about 5 years old. Thanks again!

Hi paul here. The open limit was going to be my first guess when you said the main blower came on right away. As soon as the limit goes open the electronic board keeps the blower on. Glad you got it going , sorry i missed you last night. Later Paul