# furnace problem ? **URL:** \ **Category:** General Inspection Discussion\ **Created:** [December 3, 2008, 9:46pm UTC](https://forum.nachi.org/t/furnace-problem/34145 "2008-12-03T21:46:48Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Aaron\_lore](https://avatars.discourse-cdn.com/v4/letter/a/cdc98d/32.png) [@Aaron\_lore](https://forum.nachi.org/u/Aaron_lore)\ **Post date:** [December 3, 2008, 9:46pm UTC](https://forum.nachi.org/t/furnace-problem/34145/1 "2008-12-03T21:46:48Z")
I have a 17 year old furnace that cycles on and off every 5 min. or so. I have been told to leave blower running so I don’t ruin blower, but is there any adjustments that I can make to stop this problem. Or is this a problem? ---
**Author:** ![mlarson](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mlarson/32/89225_2.png) [@mlarson](https://forum.nachi.org/u/mlarson)\ **Post date:** [December 3, 2008, 9:51pm UTC](https://forum.nachi.org/t/furnace-problem/34145/2 "2008-12-03T21:51:44Z")
> [@Aaron\_lore](#): > > I have a 17 year old furnace that cycles on and off every 5 min. or so. I have been told to leave blower running so I don’t ruin blower, but is there any adjustments that I can make to stop this problem. Or is this a problem? When is the last time it was serviced? Could be several things causing this. The only one you should consider are checking to make sure your air filter is clean. There can also be problems with the burner lighting system or blower blower control but these are well beyond the expertise of the typical home owner. Be safe and and contact a HVAC service technician. ---
**Author:** ![wwilson3](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/wwilson3/32/58197_2.png) [@wwilson3](https://forum.nachi.org/u/wwilson3)\ **Post date:** [December 3, 2008, 10:05pm UTC](https://forum.nachi.org/t/furnace-problem/34145/3 "2008-12-03T22:05:32Z")
_is it the burner coming on off every 5 min or the fan? if it is the fan the furnace needs a cleaning the heat exchanger may be full of soot, if it the burner it may be the high limit switch cutting in and out_ ---
**Author:** ![bboerner](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/bboerner/32/354840_2.png) [@bboerner](https://forum.nachi.org/u/bboerner)\ **Post date:** [December 3, 2008, 10:22pm UTC](https://forum.nachi.org/t/furnace-problem/34145/4 "2008-12-03T22:22:06Z")
[hvac-talk.com](http://hvac-talk.com) Pro’s all over the place on that board that can tell you specifics. ---
**Author:** ![dandersen](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/dandersen/32/59398_2.png) [@dandersen](https://forum.nachi.org/u/dandersen)\ **Post date:** [December 3, 2008, 10:40pm UTC](https://forum.nachi.org/t/furnace-problem/34145/5 "2008-12-03T22:40:23Z")
Also can be the thermostat. It takes more than symptoms to tell you what’s wrong with a gas heater. Call for service. ---
**Author:** ![rray](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rray/32/2162_2.png) [@rray](https://forum.nachi.org/u/rray)\ **Post date:** [December 4, 2008, 6:37am UTC](https://forum.nachi.org/t/furnace-problem/34145/6 "2008-12-04T06:37:44Z")
It’s short cycling. Many possible reasons. Call your local heating and cooling professional to determine the problem and repair options. ---
**Author:** ![gluck](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/gluck/32/1787_2.png) [@gluck](https://forum.nachi.org/u/gluck)\ **Post date:** [December 4, 2008, 2:06pm UTC](https://forum.nachi.org/t/furnace-problem/34145/7 "2008-12-04T14:06:45Z")
Three problems you never ignore; 1 - your mother-in-law 2 - the brakes on your car 3 - your furnace Call for service YESTERDAY ! ---
**Author:** ![rray](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rray/32/2162_2.png) [@rray](https://forum.nachi.org/u/rray)\ **Post date:** [December 4, 2008, 2:37pm UTC](https://forum.nachi.org/t/furnace-problem/34145/8 "2008-12-04T14:37:37Z")
Hey, George. I’m perplexed. So you do not ignore your mother-in-law, but you can ignore your spouse? Hmmmmmmmmmmm. LOL ---
**Author:** ![wchris1](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/wchris1/32/101_2.png) [@wchris1](https://forum.nachi.org/u/wchris1)\ **Post date:** [December 4, 2008, 6:18pm UTC](https://forum.nachi.org/t/furnace-problem/34145/9 "2008-12-04T18:18:55Z")
> [@gluck](#): > > Three problems you never ignore; > > 1 - your mother-in-law > 2 - the brakes on your car > 3 - your furnace > > Call for service YESTERDAY ! **George,** 1 - When she was alive - AGREE 2 - AGREE 3 - AGREE - Serviced this past weekend **Aaron,** Recommend calling your local trusted HVAC contractor . . . several possibilities . . . call now. ---
**Author:** ![jwantz](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@jwantz](https://forum.nachi.org/u/jwantz)\ **Post date:** [December 7, 2008, 10:58pm UTC](https://forum.nachi.org/t/furnace-problem/34145/10 "2008-12-07T22:58:00Z")
What “short-cycles” the burner or the blower? If the burner short cycles it mayy be a clogged filter, causing the “high-limit” control to turn off the burner. ---
**Author:** ![John\_Dee](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/john_dee/32/2157_2.png) [@John\_Dee](https://forum.nachi.org/u/John_Dee)\ **Post date:** [February 2, 2009, 9:10pm UTC](https://forum.nachi.org/t/furnace-problem/34145/11 "2009-02-02T21:10:28Z")
Replace the " Fan Switch". aka ;cam stat, fan limit combo , etc; it is weakened by the helix bi metal that over a long period of time weakens. to stop it from short cycling , it would be wise to seek a professional, They have a free directory and resources that are local nationally to everyone. also , you can ask any question and get life time support or help as long as the site is open and you are a member. [HvacrTalk.com](http://HvacrTalk.com) 😉 ---
**Author:** ![rsole](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rsole/32/172986_2.png) [@rsole](https://forum.nachi.org/u/rsole)\ **Post date:** [February 5, 2009, 6:04pm UTC](https://forum.nachi.org/t/furnace-problem/34145/12 "2009-02-05T18:04:24Z")
Good possibility that it is the thermostat. There is an adjustment for what is called anticipation. If that is off or not working, it will cause the furnace to short cycle.