This is very strange.
So, I have a Trane XE80. My current problem is: There is no gas ignition (or furnace appears to shut down) unless I jump the R/W in the furnace control board.
A couple of days ago I noticed the furnace did not start in the morning. I checked the breaker and reset it and it came on… no issues. Later that day in the evening, the same problem but this time resetting the breaker did not do the trick. The furnace appeared to start but it was shutting down after a while. This is what I did:
1. Reset the breaker and checked the firing process. The thermostat
called for heat, the induce draft motor came on, the igniter glowed, the flame came on but the furnace shutdown 1-2 secs afterwards.
1.1. - I found the flame sensor could potentially be the problem. I cleaned it without removing it with a soft rug and tried again. It worked, once.
1.2. - I read in the forum using sand paper is the way to go to clean the sensor. I removed it, cleaned with sand paper being careful to not damage anything… Put it back on, it did not work. BUT NOW it stops right after the ignitor glows. There is a click, it seems like a call to shut the system down and that’s it
2. The red led blinks normal. 1 blink per second and 2 per second when get a call for heat.
3. Checked the igniter and it was white in the middle. I figured based on some notes from other users this could be the problem. I bought a new igniter and installed it. Same problem. It stops right after the igniter glows. The furnace tried to start twice or three times but that was it. Checked the led for a diagnosis code and same as before. Steady 1 sec blinking.
4. Decided to jump R/W just to cover all basis and it came on… works without problem.
5. Removed the jumper cable and tried again using the thermostat to call for heat. Same PROBLEM again.
6. Jumped the board once again, it works, no problem.
7. Removed the jumper cable, SAME problem. It stalls right after the igniter glows.
1. If the problem is the thermostat, why is it able to send the signal for heat? Cables does not seems to be the problem…
2. Is there a problem running the furnace with a jumper in the meantime?
Appreciate your help,