okay a couple of days ago i asked a question about this and got some very helpful answers so here i am again. my led light is telling me that i have an open limit switch. so i went and bought new one and replaced it (well guess what i have 4 doh!!) so i started cleaning everything (with the gas and power off of course) and had a friend over... he checked the fuses he saw that one was not blown but weak so he cleaned it off and pluged it back in and wala heat... he left furnace working great ... for about 15 minutes. bam... back to just cold air. he bought some new fuses again wala heat... 15 minutes later ... yep cold air. now its saturday night... cold here in utah... plz help thanks!!!!
2006-11-04 18:34:58 · 8 answers · asked by Anonymous in Home & Garden ➔ Maintenance & Repairs
i dont have a code book just the chart inside the furnace... says 4 blinks "open limit switch"
2006-11-04 18:51:05 · update #1
when this all started my furnace just blew cold air constantly.. the gas would not ignite at all...nor would the fan turn off (except when all power is shut off) the only time ive had heat in the last two days is when we pulled out and replaced the fuse... then it was for only a very short period of time...then just cold air again
2006-11-04 19:57:56 · update #2
yep got a brand new filter... although i admit my old one was pretty gross... which i think may have led to all these problems
2006-11-04 19:59:10 · update #3
Hi,it seems like you have more than one problem,if you are blowing fuses,you probably have a shorted low voltage wire,unless i am misunderstanding you and the fuse is a fusible link,a limit switch.Weak fusible links will fail.If it is the low voltage fuse you can eliminate the problem by using an ohm meter to find the shorted conduuctor.You should replace your weak link.If your filter was severely plugged,you probably have a dirty blower wheel,secondary heat exchanger,(if you have a high efficiency furnace),and possibly evaporator coil.Find out what your temperature rise is by using athermometer onthe return and supply ducts,compare this to the temp rise range on the furnace.Using a higher fan speed may get you by until you can have the furnace cleaned out.Also a cracked heat exchanger could be causing the limit failure,If you don't have a carbon monoxide detector get one.If you watch the fire in your fur nace and the flames jump,when the fan starrts this is likely the case.If you think this has happenned you can call your local fire department to check it on a non emergency basis.You can also call a heating contrator good luck.
2006-11-05 01:21:11 · answer #1 · answered by Scott EThe anode rod inyour hwh 2 · 0⤊ 0⤋
open limit switch is such a generic code. If the switch was constantly bad you would not have any heat at all. I would assume that you have looked, AKA changed your air filter, bad air flow will cause high limit trip. Another culprit could be the pressure switch. that would give you heat for a short time and then open up. Does the furnace give you heat every time you turn the power off. That in itself is a good indicator of where to start for a good diagnosis
2006-11-04 19:53:42 · answer #2 · answered by Leo C 2 · 0⤊ 1⤋
help is on the way,,,,,,its not a fuse problem, the furnace is running about 15 min then no heat, tells me that your main limit switch is bad, the big black one that goes in the wall of your furnace, has 2 wires connected to it, change this out and you should be good to go,,,good luck, tell ya how to find out for sure yourself if this is right, take the 2 wires off of the black square limit and put them together and tape them up and start the unit up, if it runs and don't cut off than this is it,,,, be sure to take them back apart and replace it if it is ,,,good luck
2006-11-05 11:26:19 · answer #3 · answered by technician68 3 · 0⤊ 0⤋
I work for a Lennox dealer, and have had much experience with that series of furnace. Thor is right in regards to the burners being dirty, for the love of god, please have that unit serviced, although I don't share his hatred of DSI furnaces. Although dirty burners and delayed ignition are the most likely problems, gas pressure, gas valve operation and heat exchanger status could all be contributing factors to your current issue. Please have a professional service this unit. (and not one of those fly-by-night companies either) I can't speak for other furnace dealers, but any Lennox dealer will most likely be pretty reputable due to Lennox's fairly strict regulations on who can and can't sell their furnaces.
2016-05-22 00:31:57 · answer #4 · answered by ? 4 · 0⤊ 0⤋
If this is a high efficiency furnace, check to make sure the vent pipes are no blocked/clogged. Typically one or two white PVC pipes exiting the house.
2006-11-05 05:21:57 · answer #5 · answered by frogpaws 2 · 0⤊ 0⤋
Is the fuse the right amp ? Sounds to me like the fuse is getting too much juice. back track it to the source and see if there is an intermittent ground, frayed or loose connection. wish I could be more help
2006-11-04 18:53:55 · answer #6 · answered by WESTERN M 2 · 0⤊ 0⤋
My husband is a furnace guy, Do you have a code book for the LED Code? Could be a weak ignighter...
2006-11-04 18:49:36 · answer #7 · answered by ? 2 · 0⤊ 0⤋
Make sure all your vents are wide open. Also check that your flue pipe is clear.
2006-11-05 13:09:51 · answer #8 · answered by Mike M 1 · 0⤊ 0⤋