3 flashes yes, but I've got more questions!

[jbirch]

I have the 3 flashes, on my TUE100, however I don't have 115v at the vent motor nor from the board (obviously). Does the board have a lockout and need to be reset. Or do I have a bad board?

Sorry, n.e.i. I have a dual fuel system. I didn't check the second stage heat for 24v. I'll try that when I get back home. I went ahead and got a board at lunch time just in case.

 

[PaulRicklefs]

I have the 3 flashes, on my TUE100, however I don't have 115v at the vent motor nor from the board (obviously). Does the board have a lockout and need to be reset. Or do I have a bad board?

Sorry, n.e.i. I have a dual fuel system. I didn't check the second stage heat for 24v. I'll try that when I get back home. I went ahead and got a board at lunch time just in case.

If you've shut the power down to the system for 30 seconds or so and turned it on again that's all you need to reset the system. If your draft inducer motor isn't starting up and you've checked for power your relay is likely cooked. Most boards have an integrated relay so you may be looking at a new board. You can try to tap it to see if it starts up. If you've tried all that I'm guessing you are into it for a new board. $200-300.

If you want to absolutely confirm it you can apply power directly to your draft inducer via a 120v extension cord or jumper it at the board. Be careful. If the motor fires up, you have a buggered board.

 

[jbirch]

Thanks, for the reply, Paul! I replaced the board and I still have the same problem. The thermostat is calling for heat, but the inducer motor is not getting 115V from the board. The pressure switch is not stuck closed either. I was told from Trane tech. support to check the voltage coming in and the ground. The blower motor comes on. Any suggestions? I guess its possible that the new board is bad as well.

 

[PaulRicklefs]

Thanks, for the reply, Burning! I replaced the board and I still have the same problem. The thermostat is calling for heat, but the inducer motor is not getting 115V from the board. The pressure switch is not stuck closed either. I was told from Trane tech. support to check the voltage coming in and the ground. The blower motor comes on. Any suggestions? I guess its possible that the new board is bad as well.

I'm just wondering if your inducer motor is cooked and is causing the board to short out. Try putting power directly to the inducer and see if it spins up.

 

[jbirch]

I give it a try when a get back home. Thanks, again!

 

[jbirch]

Hey, Paul. I talked with another tech. that I had out last night, (I've got kids, I can't devote all my time to it!). Anyway, he did connect the motor directly to 115v and it ran. So........I guess that goes back to the board? Any more thoughts?

 

[PaulRicklefs]

Hey, Paul. I talked with another tech. that I had out last night, (I've got kids, I can't devote all my time to it!). Anyway, he did connect the motor directly to 115v and it ran. So........I guess that goes back to the board? Any more thoughts?

Getting a little stumped on that one. He probably checked the transformer for 24v I assume.

 

[jbirch]

He and I both did. I'm going back to Trane parts at lunch to get another board. Do you know if they had trouble with these boards in the past for the inducer motor circuit? I installed this furnace in Feb. of 2005.

 

[PaulRicklefs]

I don't know of any specific problem on the trane furnaces. I usually install other brands like ducane and keep-rite. I've worked on tranes many times and I have certainly run into this problem before. But if you've replaced the board then it sounds as if there is something wrong with the motor.

One thing that I would check is the amperage that the motor is using. I have a device I put around the hot wire and it tells me the amps. If it jives with the amp usage on the motor then everything is cool. If it's higher, then there is something wrong with the motor and that could fry the board.

I'm going through the system in my head and it's got to be something between the board and the inducer.

Let me know what you figure out..

 

[jbirch]

Yes, but if the board is getting "fryed" there should be a sign of that on the board. I'm going to check if I'm getting voltage between line neutral and the common. I was told that if it is above 2v then I have a ground issue. Then replace the board if that checks out, unplug the inducer motor and check for 115v coming from the board. I have a clamp meter here at work, but my cohort has it out today. And dang it, he doesn't even need it! The cold air is coming this weekend and the heat pump just won't keep up!

 

[jbirch]

Well, I found the neutral wire coming to the furnace was burnt up. I repaired that and installed the new board. Still the same problem the t-stat calls for heat, but the inducer motor never gets 115v to turn on, the blower motor comes on, then the furnace faults out with the 3 flash sequence. Also, I realized Trane parts had given me a control board for a silicon nitride ignitor. This furnace does not have that type of ignitor. Will that make a difference?

 

[PaulRicklefs]

I know that the silicone ignitors can directly replace the standard glow-type style and they both run off 120v so that shouldn't matter. Regardless your inducer motor should start up long before your ignitor starts to glow. I think I would suspect a faulty inducer motor in your case. A clamp meter would confirm amperage. This is a tricky one that's for sure. If you by pass the board and put power directly to the inducer and let it run does it sound ok? If it rattles or starts slowly that may be a sign of bearing failure. Also you may be able to try leaving the inducer connected to 120v and see if everything else works fine. In order to get heat going you may have to run the inducer constantly for now and let the furnace cycle on and off on it's own.

 

[jbirch]

Well, finally got it a week from last Friday. It was the FREAKIN pressure switch!! The switch would measure open with a meter, but the board was sensing closed on startup, my meter was not picking it up. Before starting the furnace, pulled off one side of the pressure switch wire, inducer started, put back on furnace fired up. Replaced pressure switch all is good!! Take care all and have a Happy Thanksgiving!

 

[PaulRicklefs]

Well, finally got it a week from last Friday. It was the FREAKIN pressure switch!! The switch would measure open with a meter, but the board was sensing closed on startup, my meter was not picking it up. Before starting the furnace, pulled off one side of the pressure switch wire, inducer started, put back on furnace fired up. Replaced pressure switch all is good!! Take care all and have a Happy Thanksgiving!

Glad to hear you are up and running again. Too bad that meter didn't catch it. That's how it goes sometimes!