How to Test Sequencers & Fan Delays

 How do sequencers and fan delay relays work, and how do you troubleshoot them in the field? So first, let's go over how they work and then I'll show you how to troubleshoot them. So inside here, and you have one that has two tiers, A single tier doesn't really matter. Just make sure you use the right one, or whatever you take out, you replace it with.

But inside, if you look here, there's a. A connector on each side with a little piece of metal, and then there's a gap. And on top of that sits two round metal discs, uh, fused or glued together. And since they're different metal, which is why it's called the by metal disc, the metal heats at different rates.

So one gets hot faster than the other. When that happens, it causes it to buckle very much like, um. A little disc, it just pops. And now you'll have contact from here through the disc out to this side, and that will move the connectors that are in the top half of this. And very often what happens if you have two is one will come on before the other.

Hence the time delay relay. So if you have an heating, heating element, the heating element will get warm. It'll get hot. Then the fan comes on. So when the does blow air through the duct work, you have hot air coming out immediately. So it waits a little while to build up heat. Then the fan comes on and blows the heat out when it turns off.

You wanna blow all the remaining heat out of the duct work, which is why it runs longer, uh, after the heating element itself is shut down or turned off. And so that's how it works inside. Now how you test this again, we go back to what transformer? I have 120 volts. I put one wire on this side. I put one wire on this side.

Now let's look at our multimeter. So we can hear the tone. This is normally open, which means there's no connection until it's activated. So the time delay is the 30 seconds that you have to wait or the 60 seconds or whatever the numbers are on top. So I have this wire on one side. I have one here. Let me try to get this so it'll stay.

There we go. Now I put these on top. We are gonna do our best to get you to be able to hear the actual click. So pay close attention, and you'll notice there's no continuity. And now there you go. You heard the click. Now we have continuity. Okay, so now that means a voltage can go through. So whatever you need to power, energy in, energy out, fan motor, whatever that is now.

It's as important how long it takes to turn on. It's just as important as how long it takes to turn off. So I'll take one of these off. And you may be able to hear the click, so let's see if you can hear it now. This is cooling off and blowing all of the hot air through the duct, work into someone's home to give you a higher efficiency system, and it costs you less to run it.

Typically, it's 30 to 90 seconds, somewhere in that neighborhood, and you just have to wait. And if it shuts off too soon, you replace it if it, uh, takes too long. Then you replace it. So it's a very good idea to know exactly how long it should take

up. There's the click. Okay, so now

you know that this works as long as it's generally in the time that it's supposed to be. A few seconds, plus or minus is perfect, but that's how you test this one. That's how you test this one. This just is stacked twice. It's called a double stack, and it will be the same exact way. And all of these function by having a bi-metal disc, two different metals glued together, that gets warm bends and creates a contact right through here to make these pass energy from the power supply to the component itself.

So that's how sequences work and that's how you test them.