No voltage to Bryant 373LAV igniter

1056 Views 2 Replies 3 Participants Last post by HVACDave, May 16, 2016

StumpedInMI

Discussion Starter · May 16, 2016 (Edited)

The furnace will not fire.

The insides are clean. It has been running fine. The filter is now new, but the old one was not horrible. We had some significant wind recently, but none of the limit switches are tripped.

When I reset the power, the big blower runs about 90 seconds, the small blower runs for about 30 seconds and you can hear a faint click followed by a louder click like it is trying to light, but it doesn't. It does the click sequence 3 times then shuts down with the ignition lockout code 13 I think it was.

The igniter does not glow red but shows a complete circuit with the continuity tester. During cycles I can hear and smell the puff of gas, but no ignition.

I tested the 120v to the igniter, but for the most part that was zero all through the sequence with the following exception. When I hear a faint click soon after the small blower starts, I see a momentary blip of voltage going to the igniter but it instantly falls back to zero. It happens to fast I cannot even see a number. About 15 seconds later I hear a louder click and smell & hear the gas.

I did not see where any limit switches have tripped. I pressed the center switch on three. I checked 4 total and they are complete circuits showing continuity. 2 were above the burner, the main one in the firebox, then another up top.

The green ground at the burner is firmly attached now. It was slightly loose.

This unit has ran fine for 20 years.

Could it be anything other than a bad control board ? Thank you in advance.

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supers05

· #2 · May 16, 2016

You could try plugging in the igniter for a few seconds, straight to 120v power. It should draw around +2A. (it'll be extremely hot, so take precautions. Don't touch the element even when cold) If it glows, you'll probably need a control board.

To verify that everything else is working, you can try to light it with a BBQ lighter. (After the louder click) put the flame of the igniter close to where the hot surface igniter would be. (but don't touch the element)

If the furnace fires manually, and the igniter glows on the test bench, then order the circuit board. Turn off the furnace until you replace it.

Cheers!

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