I tried firing up my furnace today for the first time this year, and it will not ignite. When the furnace is turned on the blower motor starts, the igniter lights up, I can hear a relay click (assuming the gas valve relay) the funace does not ignite a flame, I do not smell gas, the gas valve is on, the main gas valve is on, I checked the pressure switch which seems to be working properly. After 3 cycles of this I get a single blinking light which indicates ignition failure (duh) says to check gas flow, gas pressure, gas valve, and flame sensor. Well the gas is on and my hot water heater which runs off the same gas feed is working just fine. The flame sensor is out of the equation as I am not even getting any starting flame for the flame sensor to pickup. I am guessing the gas valve is the problem but, it worked fine last year when I shut it down for the season so is it possibly clogged from dust? Any help would be appreciated.

The cheapest thing to do first is to clean the flame sensor. A bit of sand paper or steel wool will do the trick. Stay away from the ignitor since it is sensitive.

After it is cleaned try the furnace again and post back. Here are a few pics of what the flame sensor might look like.

If the flame sensor does not fix the problem then you need to check the ignitor to see if it is glowing. You will need to be at the furnace the moment it is turned on to see if you can detect a glowing in the burner compartment.

Ignitors look like these

Quote:

---

Originally Posted by hvac1000

The cheapest thing to do first is to clean the flame sensor. A bit of sand paper or steel wool will do the trick. Stay away from the ignitor since it is sensitive.

After it is cleaned try the furnace again and post back. Here are a few pics of what the flame sensor might look like.

---

Ok the flame sensor is not the problem. I am not even getting a flame for the flame sensor to sense...
The igniter does glow as I stated in the original post. Then I can hear the gas valve relay click but there is no flame that ignites.

Since you already TESTED the flame sensor since you stated it is not a dirty flame sensor I suggest you put your volt meter on the gas valve and see if 24 volts are being supplied to the valve during a call for heat. The voltage should be there right before the unit shuts down.

I will give it a try and let you know thanks