no pilot light

adrenalic

Hi
I have a Bryant (BDP) plus 90 model 398A gas [COLOR=blue! important][FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif][COLOR=blue! important][FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]furnace[/FONT][/FONT][/COLOR][/COLOR]. I woke up this morning and the house was cold. I tried to restart the furnace, the motor starts but NO ticking sound for the pilot light and so the pilot light doesn't come on. the motor keeps on running and no pilot light . I replaced the circuit board with a new one last year. Do you think it is the spark ignitor not working?. how do I test it. could I just replace it without testing and hope it was the problem. anything I need to worry about when I replace it? I know it has " [COLOR=blue! important][FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif][COLOR=blue! important][FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]high [/FONT][COLOR=blue! important][FONT=verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif]voltage[/FONT][/COLOR][/FONT][/COLOR][/COLOR]" written on it. so, I will teurn off the electric switch before I start. Thanx for any help.

SKIP4661

Start by checking the drain hoses and make sure the drain is clear.

adrenalic

what drains?

SKIP4661

That model may have a black trap mounted to the blower housing in the bottom of the furnace. It is kind of behind the circuit board. This trap will have 2 hoses going to it. Pull the hoses off and see if any water is backed up in the furnace.

adrenalic

pulled the 2 hoses from the black trap. No water back up is evident.

adrenalic

I also unhooked the black trap and the pvc tubing, cleaned them all up and reassembled and connected the 2 tubes. still no go.
the pilot light is not getting a signal to click and ignite.

SKIP4661

If you have a meter you can check continuity with, remove the burner box cover, unplug the 3 wire pilot wires and check for continuity across the wires. The schematic will tell you whats normally open and closed.

adrenalic

burner box cover. Is it the box which has a little window where you can see the pilot lite?.

adrenalic

if it is. I removed 3 screws from the bottom and tried to remove e front cover. It is jammed. could it be ruste or glued? how hard should I pull?.

SKIP4661

You might have to pry the cover off. Sometimes they are stuck pretty good.

adrenalic

OK, I was able to remove the cover.
I tried to start the furnace with the cover off, and it did. after the inducer motor started, I heard the ticking sound and few seconds later the pilot light came on, I covered the burner box and all flames ignited . I am afraid when the furnace goes thru the next cycle the pilot light will not come on again. does this help in diagnosing what is going on?

adrenalic

Problem solved.
the problem was with the intake pipe. when I took off the burner box I could see a lot of junk behind the strainer of the intake pipe. unscrewed 4 screws on top of the intake pipe and disconnected it from the burner box and removed the dirt .
I hope this will help someone else.
Many thanx to Skip. you led me to the burner box.

dac122

Yup. Debris, kids and pests are sworn enemies of intake pipes.

Basically your inducer wasn't able to pull enough vacuum due to the blockage to close your pressure switch. The system worked like it was designed to keep you safe.