[ronney]

Hi guys,

Furnace is an American Standard mod# aud080c936j0

Problem: Furnace diagnostic light flashes fast (asking for heat).
Inducer comes on.
igniter does not come on.
Furnace repeats sequence 3 times and then enters lock out mode.

What I tested when the unit was calling for heat:
I have 28 volts to both terminals of both limit switches.
I have 28 volts to all 3 terminals of the pressure switch.
Tested continuity of the igniter and it was good.

I am thinking the board is bad. Am I missing somthing else I should check? Does the igniter have to fall under a certain resistance to function? (I only tested continuity). Thanks for the help.

 

[roughneck]

Does the igniter get power?

 

[ronney]

Does the igniter get power?

Good question. I cant touch the terminals when its plugged in with my meter. Can I disconnect it and test the harness coming from the board?

 

[roughneck]

Yes you can

 

[yuri]

Maybe not. The newer boards check for continuity of the igniter when they startup. If you disconect it the board may show a fault code. You should be able to stick your probes in the molex connector socket. Some use a reduced voltage like 80 volts. That is stamped on the sticker on the igniter which is usually made by Norton.

 

[WyrTwister]

When you are testing for 28 VAC power , are you testing with one meter probe in contact to the C - Common ?

Help me out here , is the igniter 120 VAC ? Hot surface igniter ?

Can you post a photo of the wiring diagram ?

God bless
Wyr

 

[user_12345a]

Pull the ignitor and visually inspect it. check continuity.

if you know the ignitor type, you can look up what the resistance should be and compare.

more likely to be the ignitor than board.

 

[ronney]

When you are testing for 28 VAC power , are you testing with one meter probe in contact to the C - Common ?

Help me out here , is the igniter 120 VAC ? Hot surface igniter ?

Can you post a photo of the wiring diagram ?

God bless
Wyr

I tested the contact to ground wire on unit.

The igniter is a TRANE IGN00145 80 volt. Sorry i will post pics tomorrow when i get back to the house. Thanks

 

[ronney]

Pull the ignitor and visually inspect it. check continuity.

if you know the ignitor type, you can look up what the resistance should be and compare.

more likely to be the ignitor than board.

Here is the pic of the type of igniter I have. It is a "bar" type with no visible damage.

 

[yuri]

VERY rare those burn out. Need to check the resistance of it in ohms. Not sure what that is as I sell Lennox.

 

[WyrTwister]

Do your testing of " low voltage " circuits / components with one probe touching the C - Common wire / terminal . The other to what you wish to measure voltage . ( 24 VAC )

Do your testing of " line voltage " circuits / components with one probe touching the N - Neutral wire / terminal . The other to what you wish to measure voltage . ( 120 VAC )

God bless
Wyr

 

[beenthere]

Check the ohms of the ignitor. Its probably the problem, but until you check it, or replace it, can't say for sure.

 

[ronney]

Check the ohms of the ignitor. Its probably the problem, but until you check it, or replace it, can't say for sure.

I have a Trane IGN00145 80 volt igniter. I can't find the resistance values online anywhere. Does anyone have a clue what it should read?

 

[beenthere]

Less then 180 ohms.

 

[zappa]

I have a Trane IGN00145 80 volt igniter. I can't find the resistance values online anywhere. Does anyone have a clue what it should read?

Yours is a silicone nitride which should read around 13-18 ohms.