[chhfsc]

Payne 394jaw036045 furnace - not been used for over a year (was working before).
Pilot came on when call for heat, but furnace does not.
Gas valve is sx345ns0x2, it has 5 electrical terminals, terminal 2 is connected to terminal 3 with a black wire. 26VAC from 3 to 4 and 3 to 5, 0VAC from 1 to 2.
Valve terminal to the controller connection as follows:
Wire color----Controller----Valve terminal #
white---------- W ---------------1
yellow--------- Y ---------------4
green--------- GC --------------5

Is terminal 1 not getting the voltage to open the main gas valve?
If yes, what is the problem? Controller board?

 

[yuri]

Does it have what in the biz we call a "3 wire pilot burner"?

Looks like the one in this pic.

They have a bi-metal heat activated warp switch which needs to close and allow power to the board to turn on the main valve. They stick when they get old.

DO NOT buy one that is not a OEM Payne/Carrier type as we have had problems with no name Chineez knockoffs not working.

There is a way to test them but I have not seen one in several years. That old furnace is obsolete where I am. Used to run into them.

 

[chhfsc]

Does it have what in the biz we call a "3 wire pilot burner"?

Looks like the one in this pic.

They have a bi-metal heat activated warp switch which needs to close and allow power to the board to turn on the main valve. They stick when they get old.

DO NOT buy one that is not a OEM Payne/Carrier type as we have had problems with no name Chineez knockoffs not working.

There is a way to test them but I have not seen one in several years. That old furnace is obsolete where I am. Used to run into them.

Yes, it has a 3 wire burner. Can it be cleaned or repaired?
Is it difficult to find and replace?

 

[yuri]

You have to replace it and can get it from americanhvacparts.com or supplyhouse.com.

It is fairly easy to replace as long as you have done some mechanical repairs on motors or computers and are good with your hands. Not hard to find. Payne is owned by Carrier so it may be a Carrier part when you get it.

Stay here today and maybe another tech can tell you how to test it. Was very rare where I am and I have not seen one in 5 years and forgot how.

 

[chhfsc]

You have to replace it and can get it from americanhvacparts.com or supplyhouse.com.

It is fairly easy to replace as long as you have done some mechanical repairs on motors or computers and are good with your hands. Not hard to find. Payne is owned by Carrier so it may be a Carrier part when you get it.

Stay here today and maybe another tech can tell you how to test it. Was very rare where I am and I have not seen one in 5 years and forgot how.

The pilot flame is going straight up, could the problem be the pilot flame not heating the bimetal?
To remove the 3 wire switch, looking downward on the switch assembly, which way should the nut be turned? clockwise or counterclockwise.

 

[yuri]

It does not look like the flame is hitting the bi-metal on the left.

There is a orifice inside the unit to control the flow of the pilot gas and it may be dirty. Not sure if you can remove and clean it if there is dust in it.

Do you burn Propane? The flame looks very white and Propane can do that.

The pilot gas pressure regulator in the gas valve may be not letting enough through. Most of the time it is a dirty orifice.

To replace the unit you remove the 2 screws holding it to the bracket and loosen the pilot line tube. Nut is the same as any bolt or plumbing fitting. Righty tighty, lefty loosey. You can see the brass/bronze nut in my picture in post #2.

Not sure if you can check the pilot gas pressure as I have never had to do it but it could be a problem. I would see if you can clean the orifice and if that does not solve it, replace the 3 wire unit.