Gas furnace not starting on its own

Reply

  #1  
Old 02-01-07, 09:26 AM
Member
Thread Starter
Join Date: Feb 2007
Posts: 2
Gas furnace not starting on its own

I have a Lennox natural gas forced air furnace. The furnace usually turns on and shuts off 2 degrees below and 2 degrees above the setting on the programmable thermostat. The past few days the temp inside the house has been dropping several degrees, up to 4 degrees, below the setting on the stat before I realize the furnace has not turned on. When I check the furnace it is doing nothing except for the blower is running at its normal low speed, I have the fan set to Auto. If I turn the unit off at the thermostat then back to 'Heat' then I immediately hear what sounds like a fan on the furnace kick on, then a few seconds later the ignitor starts clicking and immediately the burners ignite. After a minute or so the blower speed increases, like it should, and everything is working fine.

On top of that, some times, not always after running several minutes and raising the temp. up a degree or 2 the furnace will turn off even before it reaches the setting on the thermostat. After that I will allow the blower to kick back down to its low speed then I will turn the thermostat off, like before, and turn it back to heat and it will start back up. Any ideas? Is it the thermostat? The thermostat is only about 6 years old. It believe it was a ACE Hardware store brand, LUX is the real brand name or manufacturer of it.
 
Sponsored Links
  #2  
Old 02-01-07, 09:32 AM
mattison's Avatar
Member
Join Date: Mar 2003
Location: Cinti, OH
Posts: 5,549
The next time it is off when it should be on, remove the front panel and there should be a flashing light. Count the code and there should be a label telling you what the code means.

Do you have a clean filter in it ? If so what type is it ?
 
  #3  
Old 02-01-07, 11:33 AM
Member
Thread Starter
Join Date: Feb 2007
Posts: 2
I remember looking through the panel this morning and saw that the 2 green LED's were alternatly flashing. I did some searching online and I guess that means it had a 'Failed Ignition' and it went into 'Hard Lockout Mode'. I was looking at the furnace several times this morning but am not completly sure if that code was flashing immediately after it failed to start. However, I do believe that's when I saw it. I've had some dealings with the furnace before and luckily I remembered to look at the code. I am at work right now and unable to check the code for sure. If that is the right code what do I need to do? In the meantime when I get home this evening I will double check the code.

It's funny you should ask about the filter. I normally put these 3 month filters with Allergen filtration blah blah blah, but a couple of weeks ago I bought the cheap Walmart filters, which I don't normally do, and am currently using that. Could the filter be the problem?
 
  #4  
Old 02-01-07, 12:27 PM
mattison's Avatar
Member
Join Date: Mar 2003
Location: Cinti, OH
Posts: 5,549
I would start by cleaning the flame sensor. If you pull the cover where the burners are located the sensor should be on the far left and will be a simple metal type rod. Just clean it off with some scotch brite or a dollar bill and see if that fixes the problem.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes