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 18:36:40 · 7 answers · asked by Anonymous in Home & Garden ➔ Do It Yourself (DIY)
jen- can you ask him how to check to see which one is bad with the voltage meter... im sure my friend knows but hes not here thanks so much... is it as simple as unplugging one violet wire from one end of the limit switch and checking it with the voltage meter?? my worries is that all 4 of my limit switches kinda hook together please email me and let me know what he says thanks
2006-11-04 19:33:59 · update #1
I'm sorta coming in on this late, but it sounds like your limits are doing what they are supposed to do,, turn off the furnace when it overheats...This sounds like you have an air flow problem,,, Have you checked to make sure your filters are not plugged with dirt,,, are all your vents open,,, are your return vents clear,, not covered with a throw rug or a piece of furniture..Is your blower coming on... Do you have A/C,,, if so maybe your A-Coil is plugged with dirt... On the name plate of the furnace it should give you a limit for the temperature rise,,, This is the difference between the air in the return going to the furnace and the air in the supply leaving the furnace... it will probably be a range like 35-65,,, Example,, if you have 65 deg air going to furnace and the air leaving is 125 deg... your rise is 60 deg and it is OK.. but if you have 65 deg air going in and the air leaving is 145 deg, then your rise is 80 degrees ans it is over the furnaces rating and this will probably cause you to cycle on limit.
some limits have to be manually reset,, there will be a little red button that pops out in the middle of the switch,, just push the button in if you have this kind to reset it,,, Good Luck,, I hope this helps,, Bob G
2006-11-05 08:53:27 · answer #1 · answered by Bob G 2 · 0⤊ 0⤋
Some furnaces have a circuit board that allows for 3 failures then they lock out until you turn the power off and then back on. This could be what happened when the fuse was pulled then reinstalled. I really need to know what furnace you have manufacturer and model. There are many different furnaces out there. A simple test to find out what switch is opening is to get jumper wires from radio shack and jump the various limit switches. But- CAUTION_ they are there for a reason. Your rollout switches are there to protect gainst a fire or a blocked vent. Your fan/limit switch is there to keep your furnace from overheating due to a bad blower motor/ plugged filter, or blocked heat runs. Jumpering these switches can cause personal injury or death.
2006-11-06 04:57:10 · answer #2 · answered by avengergt 3 · 0⤊ 0⤋
Any simple meter can be bought at HomeDepot to check continuity thru the switch. Any of the limits can be bad. The meter when set will make a beep if the switch is good
23 years HVAC
2006-11-05 06:11:54 · answer #3 · answered by myothernewname 6 · 0⤊ 0⤋
You can tell which limit switch is bad buy jumping them out one by one with a jumper wire. Just put the jumper on one side of the limit then the other end to the out side on the limit. By doing this you can see which one is bad if the furnace runs then that limit is the bad one
2006-11-04 23:44:36 · answer #4 · answered by aussie 6 · 0⤊ 0⤋
He also said you need a Voltage Meter to check all limit switches and fan switches to see which one is bad!!!
2006-11-04 19:01:14 · answer #5 · answered by ? 2 · 0⤊ 0⤋
the line and pump is on your humidifier. possibly which may be defective. there is in all probability no longer something incorrect with your furnace. How previous is your humidifier? Do you have a guaranty on the finished HVAC gadget which you had put in 4 years in the past?
2016-10-15 09:44:53 · answer #6 · answered by hadad 4 · 0⤊ 0⤋
Or you can move to California ( Los Angeles ) where it is 95 degrees today!!!! Do not need a heater.
2006-11-07 11:28:51 · answer #7 · answered by Dan G 2 · 0⤊ 0⤋