# Old Lennox furnace clicking pilot light, but heat array not being lit



## Ljacob (Oct 19, 2012)

Got a HS18 Series Lennox Gas Furnace, This is probably a 40 year old or so furnace. It was inspected in September. Just had ducts cleaned yesterday. It seemed that the duct cleaning had never been done correctly up until that time. There was so much accumulated dust. I felt the duct cleaner was very thorough. The furnace worked fine before. 

Early in the morning I heard a repeated clicking sound coming from the furnace in the basement. I opened the front panel, the pilot light was on, fan blowing but array of gas heads not lit. 
I raised the heat on the thermometer and the array lit. so this may intermittent, although a new problem presently.

There is a small metal switch on the side of the box that goes up and down. I think it is usually pointed down, but I do not know what it adjusts. It appears it has something to do with the fan or air flow. Should that be up or down? UP it seems keeps the flow going even if the heat is not on. That does not seem appropriate to me but I am looking for information on that as well.

What could cause the clicking sound. 
I have not ordered a repair man because one visit can cost $200 and another payment per month for repair coverage. 

Can you please tell me more about this Furnace. We are concerned that it is too old, but was working fine, even ran the AC during the summer.

thanks for your expertise and time.


----------



## Skivvywaver (Mar 18, 2001)

Can you upload a picture of the switch? If you have the fan set to the on position, the fan will run whether the furnace is lit or not. If that is the case, that is why it lit when you turned up the T-stat.


----------



## Ljacob (Oct 19, 2012)

Hi thanks for your input. The switch is a simple toggle switch in close vicinity to the electrical line input into the box and the toggle switch is also 10 inches below the gas inline. With the switch up, the fan is going on with the heat, but is stops when the furnace heat goes off at temperature. 

I am thinking that possibly the duct cleaning might have dropped some dust on to the gas jets, that the fan might have blown off or burned off once it was lit..... 

I still can not tell what that toggle switch does. 

L


----------



## Skivvywaver (Mar 18, 2001)

The toggle switch is most likely the power to the furnace.Turn it off and nothing is going to work. 

Did you check the T-stat to see if the fan is set to on or auto? You want it set to auto.


----------



## Ljacob (Oct 19, 2012)

The furnace switch is in another room, but in the basement.


----------



## Ljacob (Oct 19, 2012)

It is now set on auto so the furnace goes on when the temp goes down below the desired range


----------



## Ljacob (Oct 19, 2012)

Thanks for your help. The furnace seems to going now. It may have been coughing after the first proper duct cleaning in 50 years. There were other's but they obviously did not do what they said they would.

Leah. Any one wants to know who did a great job in Toronto, let me know.


----------

