I've been reading the forums here and had two folks with the same issue as me, but they did not answer back with the result. What a bummer. I could tell that you guys were disappointed. I assure you I won't be that way.
Pretty much new to the heat furnace world and right now, I feel like I'm close to being a technician (sarcasm). So about 2 weeks ago when I woke up one morning, the fan was blowing constantly with no heat.
I thought it was the thermostat. I did some research and was told it could be the igniter. I checked the furnace and the igniter lit up bright orange. I scratched that out. But I replaced the thermostat anyways because I wanted a programmable one.
Then later I researched and saw it could be the flame sensor. I took out the flame sensor, and it didn't really look that bad, but I've already touched the flame sensor with my hands. However, I went ahead and ordered me a flame sensor, and I put it in without touching the metal piece. I turned the main switch on and gas valve switch on. The furnace went through the process and there was no flame. I turned off the switches again. I tried again and wiggled the wires a bit. I unplugged the wires from the flame sensor and sticked it back in. I looked at the circuit board and wiggled the wires just a tad bit. Then I turned the main switch on and turned the gas valve switch on, and it went through the process. I saw the flame!
Well I thought that solved it, but the back of my mind I thought there might be something else like the wiring or the circuit board and left the attic.
So it has been working for about 2 weeks up until now when I woke up to go work, it was cold. So I know it couldn't be the flame sensor. There was loud thundering and pouring rain that night, but I'm not sure if the elements could cause the heat to stop functioning.
I googled and youtubed for 5 straight hours that I felt like I knew so much about the heating system. I debated if it could be the circuit board or the gas valve at this point. I heard that the gas valve could go bad or the circuit board as well. I wanted to test this out. So when I got home, I started messing with the furnace again. Here's the part that I am not good at - testing the gas valve with the multimeter. I googled how to test the gas valve, but it's quite different. Of course, I set the black to COM and the red to VAC at 750 and while trying to test the gas valve, the red wires has a protective shield over the end of the terminal so I can't really test it. I was thinking about buying a tester that clamps over the wires? (Is that what I need to do?) I am very nervous about testing things near gas. But I am willing to try if you provide me the proper procedure.
So I stopped the testing and I started messing with the wires. I unplugged the red and dark blue wires from the gas valve and plugged back in. (By the way, I left the gas switch on but turned off the main switch.) So I turned the main switch on and still didn't work. So I looked at the circuit board and unplugged the wires and plugged back in. I held the cables and you know, just wiggle or seeing what it can do. I turned the switch back on and I saw the flame. So this time I wanted to see consistently, so I turned off the main switch and left the gas valve switch on. I waited couple of seconds and turned it back on. I see the flame again! I am positive it could be the circuit board at this moment. So 30 minutes later when the house got warm, it tried to start back up. Then it went to safety mode with the fan blowing. I went back up to the attic and did not see the flame. I turned the switch off and left the gas valve switch on. I wiggle jiggle the wires. I flicked my fingers lightly to the circuit board capacitors what not. I made sure the wires are plugged in securely on the circuit board. I also unplugged the wires from the gas valve and put it back in securely. It worked. I see flames! The house is heated up. It started back up after it got cold. So it's working as of now 7:36 pm eastern time.
But still, I am not 100% sure it could be the circuit board. It still could be a bad gas valve? I am hoping that it could be the circuit board because I can just buy and replace it. However, I am going to replace the board anyways. I have a d341122p01 50A55-571 circuit board and my furnace is a Trane xb80.
I can get pictures if needed. I only got pictures of the board and not the gas valve but I can go back up to the attic if I need to. But it's a pain getting up there.
What do you guys think? Board or Gas Valve? Or will I need to buy a volt tester that will test the wires via clamp style.
Thank you for taking the time to read this long story.