20 replies to this topic

[gonorm]

My furnace worked last week, but this week it no longer fires up.
When I set the thermostat to call for heat, the inducer fan starts but the pilot never sparks. The inducer runs for a few minutes and then shuts down. I would like to figure this out since I have some time but have not made in progress over last couple days searching the internet. Thanks.
Norm

[RegUS_PatOff]

does the Pilot Gas Valve open ?

[gonorm]

I don't hear a click that would indicate pilot gas valve opening, but it could be hidden by the inducer noise. Is there a simple test to see if the pilot gas valve operates?

[RegUS_PatOff]

should be able to "feel" the Gas Pilot Valve open, and / or smell the Gas
Check the thermal Fusible Link Fuse on the Yellow wire that connects to the Gas Valve and the Spark Generator

[gonorm]

RegUS, I separated the molex before and after fusible link yesterday and found continuity across fusible link. I will go put my finger on the gas valve and call for heat to see if there is a click. I have not smelled gas but let me put nose closer.

[gonorm]

I don't feel a click with my finger on the gas valve. I don't smell gas. The gas could be getting exhausted by the inducer fan. What next?

[RegUS_PatOff]

check the Pressure Switch (and it's tubing)
Common - Yellow
Normally Closed - Orange
Normally Open - Brown

[Dan Webster]

Blow through the tubing to make sure the vacuum between the switch and the inducer is clear.

[gonorm]

I did the pressure switch. NO and NC ok. Blew into hose and actuated pressure switch. Both sides changed state. Blew into hose from pressure switch to inducer. Air moving. Also found continuity on the temp limit switch behind the gas valve.

[RegUS_PatOff]

If the Pressure Switch is activated, there should be 24v AC (measured to ground) at the
Gas Valve
4 Yellow
5 Brown

[gonorm]

Noob question. Do I remove the connector and probe gas valve tab to ground or do i probe connector to ground?

[gonorm]

Yellow connector at gas valve has 26.7v. Brown connector is 0v.

[RegUS_PatOff]

either the Fuse is blown or a bad Flame Sense Switch:
24v AC at Yellow
24v AC at Green
24v AC at White (only when there's Flame)

[gonorm]

At connector PL5 feeding into the PIL I found
26v at yellow
0v at brown which feeds green into the PIL
0v at white

The 26v at yellow proves the Fusible link. I think.
Strange but also found 3.5v at yellow before touching to ground. Only did this on yellow not other brown and white connections. What do you think.

So would the 0 v at brown feeding the gas valve and 0 v a brown feeding green into the PIL indicate a problem with the Ignitor?

Thanks for your help.

[RegUS_PatOff]

(make sure the Brown / Green wires aren't shorted to ground)
You could disconnect PL5, and there should be continuity between Yellow and Green, if not, bad PIL
Jumper Yellow to Brown on (still disconnected) PL5, and you should get Sparks at your Ignitor and get Pilot Flame

[gonorm]

Checked and found both sides of PL5 brown and green not shorted to ground.

Disconnected PL5 and found no continuity between Yellow and Green on PIL side. So bad PIL.

Jumped Yellow to Brown on ILO/GV side, powered furnace, after 15-20sec sparker started and pilot lit and maintained blue flame. I then cancelled thermostat after 10sec before unit fired up.

So I need a new PIL? Can you help with part number to search. Recommend source.

Also any instructions on correct procedure to replace PIL assembly or do you just figure it out.
Looks like I have to disassemble the bottom of the fire box and remove gas fitting and couple of screws.

Nice job Sensei.

[RegUS_PatOff]

sorry, I don't know anything about that Furnace
just what I found on internet searches...
PIL part number may be
LH-680-005
LH680005
Sears $ 140
eBay $29 used
$40 +$7 new
Do a search for each of those part numbers

There was a "old" class action lawsuit or something on the Heat Exchanger on that Furnace ..
http://hipspro.com/p...iled_notice.pdf

[Dan Webster]

Is THIS you?

[RegUS_PatOff]

Is THIS you?

$ 180

[gonorm]

Thanks. "This" must be the ouch price. Man those guy must love using the markup calculator.

Can you clean these things and get them working again or are they normally shot to sh*t?

Can you reuse the sparker or do you I need a new one also?