I have a Trane XR90 that was showing a solid diagnostic light. Could wiggle the wires and the furnace would work for a few hours. Solid light wiggle the wires and board = heat. Finally wiggling wouldn't work. So I replaced the IFC board. Went to turn every thing on and now 4 blinks on the light for a Open Temp Limit Circuit... Burners light and heat up for a minute, but the fan doesn't kick in. so,did the manual reset 2 x in 30 secs, no avail. Tried to reset the limit switch, but there is no "positive" clicking feeling, it moves but not sure it is right. Anything I am missing??

thank you

If you reset the rollout protection switch and it worked for a while and now it will not work when you reset it makes me think that there is something wrong with the switch. So try again to start the furnace but this time use a jumper wire across the switch that you were working with. If that does not work there are other linit switches so try jumpering across those also one at a time.

Let me know what happens.

If you reset the rollout protection switch and it worked for a while and now it will not work when you reset it makes me think that there is something wrong with the switch. So try again to start the furnace but this time use a jumper wire across the switch tht you were working with. If that does not work there are other linit switches so try jumpering across those also one at a time.

Let me know what happens.

Thank you for the quick response. Just jumped the switch and no luck. Ignition worked, blower was blowing, tubes filled then back to the 4 blink light. What is the part under the burner box w/ 2 yellow wires attached? Looked to be a sensor??

thank you for the quick response. just jumped the switch and no luck. ignition worked, blower was blowing, tubes filled then back to the 4 blink light. what is the part under the burner box w/ 2 yellow wires attached? looked to be a sensor???

Update: so I jumped the switch under the burner box, and now I keep getting the quick blink LED, blower keeps running, but no fan. And it didn't kick off...

Would you please do another list of just what your problem is at this time.

Would you please do another list of just what your problem is at this time.

Now when I jumped the limit switch the blower keeps running (10 minutes) & the fire is lit, but the fan to circulate the air never kicks on. LED is fast blink (calling for heat)

Okay, so the draft inducer is running, burners ignite, but the main blower never comes on? If the main blower never comes on, the high limit is tripping(most likely not a resetable one, the resetable one is an auxiliary limit, or flame rollout). Your problem is that the main blower isn't coming on. Check wiring of new board. Check for voltage going to main blower motor.

If your fire is burning and the blower does not come on means that it is not a limit switch that is causeing the motor not to run. So use a volt meterr between the H terminal ( black wire)and the L 2 (white) terminal, do this after the burner has been burning for a couple of minutes giving the limit switch time to turn the fan on.