What does this burned furnace wire tell you?

[cannesdo]

While trying to figure out if my brake controller was alive I think I shorted something out. Furnace isn't turning on. A/C and fan do still work. Found this burned wire front and center when I took the furnace cover off. The blue wire connected to the left side of the pink connector leads to the control board. If the board is fried can you see it? And isn't there a fuse in the furnace (back behind)? If so, what is the path the current travels? Does the location of this wire tell you anything about what else is likely affected?

[cannesdo]

Def. want a Dino board...like the idea of that fuse protection. Now I just need to figure out the right size.

Looks like this one:

http://www.amazon.com/Dinosaur-Electronics-UIB-Universal-Ignitor/dp/B0002MG2IK

Think I've got it sorted. Thanks for the help!

[cannesdo]

Found this. I'm pretty sure it's my board:

"If you hear a "click", and the fan is not coming on and you have power at the TDR (the square relay at the top front of your housing), you are not getting power through the board which is the master controller of all functions of the furnace."

[westend]

You can download the service manual for your furnace at Bryant RV. Thanks again, Chris!

In the service manual will be troubleshooting steps to help you fix your furnace.

[cannesdo]

Ok...new info:

I checked the wires coming into the furnace, before they get to the board. I have power to the red and blue. Coming out of the board I only have power to the blue. Nothing on the red wire going into the sail switch (that comes out of the line of wires that comes out the side of the board. And nothing coming out of the red wire that comes out from farther back (and lower) on the board. So does that mean it's the board? How long do the boards typically last? I think this one was replaced back in 2011.

And when I turn the furnace to the on position I do hear a click about 30 seconds in

If I do need a new board...is a Dino board better than say...this one?

[cannesdo]

Chris Bryant wrote:
If the fuse in the breaker box is lighting up, the fuse is blown- replace it. I would start looking for 12 volt power right where it hook to the furnace- should be a yellow (-12v, or ground) Red (+12v) and 2 blue thermostat wires, one will have power all the time, the other just when the thermostat is calling for heat.
If you are using the meter to check- make sure the leads are in the correct places on the meter- for voltage, not current. I also often use a 12 volt test light.

I mean the fuse is working. All the fused make the tester light up when I go down the strip. When the fuse is blown it doesn't light up.

I'll check the wires. Thanks for the info!

[Chris_Bryant]

If the fuse in the breaker box is lighting up, the fuse is blown- replace it. I would start looking for 12 volt power right where it hook to the furnace- should be a yellow (-12v, or ground) Red (+12v) and 2 blue thermostat wires, one will have power all the time, the other just when the thermostat is calling for heat.
If you are using the meter to check- make sure the leads are in the correct places on the meter- for voltage, not current. I also often use a 12 volt test light.

[cannesdo]

cannesdo wrote:

Chris Bryant wrote:
Does an led flash on the circuit board? The limit switch would not keep it from starting, but a stuck sail switch would-if the board sees power through it when the blower is not on, it knows something is wrong. The sail switch is right behind those wires- the arm hangs off the bottom and goes in to the blower housing- it should be all the way down and move freely.
Other than that- checking power is really the first thing.

Does an led flash....when I've turned the furnace on? I can check.

I thought the sail switch was stationary. Ah, ok...learn something every day. Sail switch is down and does move freely.

Can you tell me how to check the power? The fuse in the breaker box is still lighting up. Have a multi-meter but the thing is still kind of a mystery to me. Would need to know what to set it on and which wires to check.

Thanks so much!

[cannesdo]

Chris Bryant wrote:
Does an led flash on the circuit board? The limit switch would not keep it from starting, but a stuck sail switch would-if the board sees power through it when the blower is not on, it knows something is wrong. The sail switch is right behind those wires- the arm hangs off the bottom and goes in to the blower housing- it should be all the way down and move freely.
Other than that- checking power is really the first thing.

Does an led flash....when I've turned the furnace on? I can check.

I thought the sail switch was stationary. Ah, ok...learn something every day. Sail switch is down and does move freely.

[Chris_Bryant]

Does an led flash on the circuit board? The limit switch would not keep it from starting, but a stuck sail switch would-if the board sees power through it when the blower is not on, it knows something is wrong. The sail switch is right behind those wires- the arm hangs off the bottom and goes in to the blower housing- it should be all the way down and move freely.
Other than that- checking power is really the first thing.

[cannesdo]

Chris Bryant wrote:
What is not clear to me is whether that white wire is spliced in with the blue wire in the connector. According to my wiring diagram, it might be (the colors are not clear on my diagram).
Those circuit boards are really very reliable now that they mount them where it gets cooling air. What is the furnace doing?

Thanks, Guys....The furnace does nothing when it's turned on. No blower, no igniter, no sound and no air moving. It's just totally dead.

It was the limiter switch in the back that I was thinking of before when I said "fuse or something inthe back of the furnace" Can that be tripped?

[D_E_Bishop]

Just for clarification, opaque or translucent has no bearing of size, it is strictly color that determines size capacity, dielectric grease may be an insulator but when faston or other connectors mate, there is a metal to metal connection and finally, they are "AMP FASTON" connectors, not Delco or Packard.

[D_E_Bishop]

I'm going to suggest that you quit thinking that the connection is the problem and listen to Chris B. I have seen millions of those faston connectors used in 120VAC circuits and I have never seen a insulated cover burned like that and not seen other collateral damage, i.e., the wire insulation burned.

Just to let you know, I worked in the traffic field for the City of Los Angeles where there are over 4250 signalized intersections and those connectors are extremely common.

[Chris_Bryant]

What is not clear to me is whether that white wire is spliced in with the blue wire in the connector. According to my wiring diagram, it might be (the colors are not clear on my diagram).
Those circuit boards are really very reliable now that they mount them where it gets cooling air. What is the furnace doing?

[dougrainer]

Lynnmor wrote:

dougrainer wrote:

Lynnmor wrote:

cannesdo wrote:
Why is one pink and one blue. Are the color coded for size? Am I safe if I go with the same color?

Yes the color indicates the wire size. Use the smallest barrel that will accept the bare wire(s) freely.

COLOR does NOT indicate wire gauge(size). You can get various Wire Gauges in almost ANY color. Now, if you are talking about the Crimp end fittings, yes, the color usually designates what Gauge wire it is designed for. But not in this case. Usually the color designates the BUTT splice connections. In this case the color is translucent, which will not indicate Gauge size. As evidenced by the Pink and Blue colors, which are the same gauge size. Doug

He was buying connectors, not wire. Good Grief!

I KNOW that. But as I stated, in this case, the COLOR of the existing connectors did NOT indicate the wire size. That is why I gave a detailed explanation on both WIRE and WIRE CONNECTORS. Doug