furnace problems

tom_43

doing repairs to an old furnace, replaced the gas control valve,installed a new 3-wire pilot. wiring is correct according to wiring dia.There is gas flowing to the gas control valve and pilot burner. But when system is turned on the pilot does not ignite the gas pilot. and yes i,m get spark at the pilot.

Mitch_4

what is

Your inlet supply pressure? What mod# of furnace and ingnition system? need more info.

Mike

Dale

Match

Well, maybe you have an old Carrier bi metal pilot. Best guess given you say 3 wires. If the spark doesn't ignite it then how about a match. If there's gas at the correct pressure it will burn. I wonder what your gas pressure is. Sounds like you are doing the Yatzee method of parts replacement. What you have purchased so far would pay for a pro to diagnose the system. Has your furnace been under water? If so lots of strange wiring connection problems can result. As the other post suggested alot more info is needed to get us past the guess stage.

oil-2-4-6-gas

.

sounds like spider webs

Brian_24

If it is a carrier or bryant you need to change the spark electrode. Sometimes when you change the three wire assembly it gets tweaked out of alingment and it is a royal pain to get it lined up. Just had the same thing yesterday. Good luck,
Brian

Greg_22

Coleman Evcon Furnace

Have: Model AGU12520A Ser# 940817853. Getting communication from t-stat to furnance,the fire chamber is firing at full capacity, but the fan is not operating. Is this the motor shot or else? Thanks for helping who tries.

Greg_22

Coleman Evcon Furnace

Have: Model AGU12520A Ser# 940817853. Getting communication from t-stat to furnance,the fire chamber is firing at full capacity, but the fan is not operating. Is this the motor shot or else? Thanks for helping who tries.

Unknown

Tom, give us some part numbers

and we can help you out. Are you a homeowner? I have to ask so please do not be offended.

You say the pilot does not ignite the gas pilot that is a little confusing. Is what you are saying that the spark does not light the pilot? That can be caused by not placing the spark gap correctly and also not placing it in the area of the best gas/air mixture.

Unknown

Greg, do you have

a control board in the blower compartment? If so what is the model number and make?

Is there 120 volts to the motor?

Is the furnace shutting off on high limit?

You could also have a bad capacitor on the motor.

Send some more info. With more info we can help you.

Greg_22

How do you tell if the furnace is shutting off in hi limit?

Unknown

Hi Limit will shut off

typically because the fan does not come on. Your post stated that the fan does not come on is that the system fan or the combustion air blower?

If the burner comes on and the fan does not run it must shut off on limit or it is dangerous.

Greg_22

Should I replace the hi limit and start there?

Unknown

Greg do not replace

the high limit!!! You need to have a professional look at your furnace.