Hello All,

I am pretty handy but have never worked on a furnace before.

The furnace is a Day & Night

Product = 373lAV024055AAJA
Model = 373lAV024055

According to the serial number it appears to have been made in the 46th week of 91.

The heater has been working flawlessly for 20 years, including this year.

A couple of days ago, it stopped heating the house.

I turned the gas to off at the gas control in the furnace and waited more than 5 minutes. Also turned off the thermostat. Then turned it back on and turned the tstat back to heat.

The fan comes on, but it does not light. You can hear some sounds and it cycles through 3 times, then completely shuts down.

I removed the front panels and again went through the off and on with the gas control and tstat.

This time, with the front panels off it should not do anything until the interlock switch is activated.

So I then manual hold the switch in to observe closely what is happening.

The fan goes on and a second or two later there is another sound, not sure what that is but at that point I believe the igniter should start to spark and it does not.

So I am failing pretty early in the sequence I believe.

Any help would be appreciated.

 

The sound you hear may be the pilot valve opening but there is no spark it sounds like. Does that appear correct? If yes, the spark generator may have failed or the high voltage wire may have come off the terminal or has poor contact.

 

Is there a way to test it? I would not think it would be a loose wire, but I can check.

The igniter does not seem to look like others I have found on the web with a large high voltage wire.

This looks much more like an igniter you would see in a BBQ grill.

 

OK, so it seems that what I posted previously is more like a thermocouple?

I do believe I have found the problem...

 

That will certainly cause the furnace not to light. The device in your previous post appears to be the flame sensor. To get 20+ years out of a silicon carbide ignitor is absolutely amazing. I prefer to replace with a silicon nitride type but finding one to fit that bracket???

 

What you have there is your pilot light. They do break and there are universal replacements for them. I bought one from a local heating and cooling service company because it was quick. If you have time, you can probably find one cheaper online.

When you install the new one, make very sure that the heating element is not touching anything and be very careful not to bump it on anything during installation.

 

Forget all I said, when you mentioned the age I assumed it had a different ignition system. Lol