furnace won't come on


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Old 10-13-09, 12:42 PM
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furnace won't come on

Gas funace, forced heat, installed in 1998. Did not use last year. Turn thermostat and nothing happens. Checked power supply switch to unit. Switch is on. Still, when I turn up/on thermostat no sound, no click, nothing. Need help/advice.
 
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Old 10-13-09, 06:03 PM
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No Heat

Make sure the furnace doors are on properly. There is a switch behind the blower door which is operated by the door being in place. If the door is off or not tight the furnace won't run.

Something else to check is: On many furnaces there is a circuit board & on that board is often an automotive type fuse.
 
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Old 10-13-09, 06:42 PM
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Dampness or humidity may have affected electrical connections from that off-year. Where is the furnace located in the dwelling, out of curiosity?

You said the switch is on but did you make any kind of confirmation that 120 volt power is getting to the inside of the furnace? And do you have multimeter to test with? Is the thermostat mechanical or digital, and if digital is the screen active, to show power, and that you are overriding any set program?

If you have a voltmeter, easy tests at the thermostat wires inside the furnace can be made after you turn up the stat -which actually will make paragraph 2 unnecessary.
 
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Old 10-13-09, 08:05 PM
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Originally Posted by ecman51`
Dampness or humidity may have affected electrical connections from that off-year. Where is the furnace located in the dwelling, out of curiosity?

You said the switch is on but did you make any kind of confirmation that 120 volt power is getting to the inside of the furnace? And do you have multimeter to test with? Is the thermostat mechanical or digital, and if digital is the screen active, to show power, and that you are overriding any set program?

If you have a voltmeter, easy tests at the thermostat wires inside the furnace can be made after you turn up the stat -which actually will make paragraph 2 unnecessary.
Furnace is enclosed just off the hallway. Will check thermostat with multimeter (thermostat is mechanical type). You said something about dampness, can you tell me what I should look for?
 
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Old 10-13-09, 08:09 PM
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Originally Posted by Grady
Make sure the furnace doors are on properly. There is a switch behind the blower door which is operated by the door being in place. If the door is off or not tight the furnace won't run.

Something else to check is: On many furnaces there is a circuit board & on that board is often an automotive type fuse.
Found switch behind panel door of unit. Seems to be making contact (makes a click when I put panel back on). Still looking for fuse you mentioned. Can you give me a hint?
 
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Old 10-14-09, 05:54 AM
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Have you checked the breaker in the main panel?
 
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Old 10-14-09, 02:31 PM
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Fuse

Your furnace may or may not have a circuit board on which may or may not be a fuse. The board, if there, is usually in the blower compartment.
 
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Old 10-14-09, 03:44 PM
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What are the make, model and serial numbers?
 
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Old 10-14-09, 04:19 PM
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Furnace off a hallway? They do that in mobile homes. Maybe you have one of those auxillary switches hiding somewhere by an exit door, that controls the furnace.
 
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Old 10-14-09, 07:57 PM
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Originally Posted by Grady
Your furnace may or may not have a circuit board on which may or may not be a fuse. The board, if there, is usually in the blower compartment.
Checked circuit board. No fuse.
 
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Old 10-14-09, 08:02 PM
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Originally Posted by ecman51`
Furnace off a hallway? They do that in mobile homes. Maybe you have one of those auxillary switches hiding somewhere by an exit door, that controls the furnace.
It's a three bdrm. two bth home with a space in the hallway like a closet, only there is a furnace set up behind the door.
I mentioned before, I found the power supply switch. It's right next to the unit on the wall and it is in the on position.
 
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Old 10-14-09, 08:16 PM
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Originally Posted by Skip4661
What are the make, model and serial numbers?
Panel has ULTRA SX80 High Efficiency on i t.
Honeywell inside. Model No. GHJO75D14-1A
Serial No. 8484A24632
Says manufactured by Armstromg Air Conditioning.
 
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Old 10-15-09, 05:15 AM
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Do you know for sure that you are getting 120v at the switch?
Have you checked the main breaker?
Did you verify you are getting 120v at the furnace?
 
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Old 10-15-09, 07:28 AM
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I'd hate for it to be 40-below out and we can't get to the part, quickly enough, as to if there is actually power inside that furnace, and/or where it might be lost at.

To be a good diagnotician, nothing can ever be assumed. For one little example, luckily for the people who call me up that do not have lights, that I am able to diagnose that their light switch is bad, quickly, and replace it, without presuming there should be power because there is a light switch on the wall.
 
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Old 10-17-09, 09:16 AM
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Originally Posted by dun11
Do you know for sure that you are getting 120v at the switch?
Have you checked the main breaker?
Did you verify you are getting 120v at the furnace?
Will check for current at the switch....
Sorry for the delayed reply. Had to work a double and sleep was very much needed. Thanks for following up.
Wish it was as easy as flipping a breaker, but this old house still has glass and cartridge fuses.....
 
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Old 10-17-09, 09:22 AM
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Originally Posted by ecman51`
I'd hate for it to be 40-below out and we can't get to the part, quickly enough, as to if there is actually power inside that furnace, and/or where it might be lost at.

To be a good diagnotician, nothing can ever be assumed. For one little example, luckily for the people who call me up that do not have lights, that I am able to diagnose that their light switch is bad, quickly, and replace it, without presuming there should be power because there is a light switch on the wall.
Appreciate the insight.... point well taken. Will check for power. Makes sense... How can light come on if there's no power to it?
 
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Old 10-17-09, 11:22 AM
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Originally Posted by poppag123
Appreciate the insight.... point well taken. Will check for power. Makes sense... How can light come on if there's no power to it?
Naturally I had to reread all the posts after what you now just said. This is the first post where I see any hint that you gave a clue it was getting power. Earlier you said you get a click. But a click in a push button switch can occur even with no electric.

I, or we, will have to spend time in totally reviewing this thread.
 
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Old 10-17-09, 12:34 PM
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Here's a thought: the problem may not be your furnace. It could be that you need to replace your thermostat.
 
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Old 10-17-09, 12:41 PM
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Originally Posted by bluesquirrel
Here's a thought: the problem may not be your furnace. It could be that you need to replace your thermostat.
Thanks for the reply....
Some one suggested I 'jump' the thermostat wires, so I took the thermostat off and just connected the two wires together... nothing.
 
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Old 10-17-09, 12:47 PM
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Originally Posted by ecman51`
Naturally I had to reread all the posts after what you now just said. This is the first post where I see any hint that you gave a clue it was getting power. Earlier you said you get a click. But a click in a push button switch can occur even with no electric.

I, or we, will have to spend time in totally reviewing this thread.
Hello,ecman51.
I see that you are online now, maybe you can help out a bit more...
The 'click' I mention before was the sound that you hear when you push the the panel switch in ( when I put the panel back on, I could hear it click). Didn't mean to say that it was, or I thought that it was electrical.
 
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Old 10-17-09, 12:48 PM
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Since you have a light [on the control board(also called a motherboard) or ignition module], does it say what the code is for how the light behaves? If on the open motherboard, it have to have a legend elsewhere, like on the inside blower door. If on an ignition module they usually print that blink code legend right on the boxy module.

Have you looked for a fuse on the motherboard?
 
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Old 10-17-09, 01:05 PM
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Originally Posted by ecman51`
Since you have a light [on the control board(also called a motherboard) or ignition module], does it say what the code is for how the light behaves? If on the open motherboard, it have to have a legend elsewhere, like on the inside blower door. If on an ignition module they usually print that blink code legend right on the boxy module.

Have you looked for a fuse on the motherboard?
When I said 'how could the light work if there is no power' it was just my saying that I understood what you were saying about thinking there was a problem with the furnace when really the problem is that there's no power.
Sorry, don't mean to be confusing.
The control board has no light on it and so far I can't seem to find any type of fuse on it.
I put the leads from the multimeter on the wires where the furnace connects in the junction box(which would be the wires coming from the fuse box). I got no reading at whereas I thought I should have gotten a reading of 120 volts.
 
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Old 10-17-09, 01:11 PM
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Now we are getting somewhere. You mean you have no 120 volt power in the black and white wire nuts, inside the furnace switchbox, if you voltmeter test between the two?
 
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Old 10-17-09, 01:22 PM
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Originally Posted by ecman51`
Now we are getting somewhere. You mean you have no 120 volt power in the black and white wire nuts, inside the furnace switchbox, if you voltmeter test between the two?
Now it seems we're on the same page....
Let me try to explain what I have on this end...
The furnace has a junction box behind the panel where it connects the power line the the wires of the furnace.
The wires run from the the furnace to a switch mounted on the wall outside next to the furnace. I imagine this was set up to be the main shut off for the unit...
I tested the white and black wires where they connect to the furnace in the box inside the unit behind the panel and there was no reading.

Hope this helps.
 
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Old 10-17-09, 01:38 PM
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Test all the way back to the main panel box. If you have a disconnect/fuse or breaker box near the furnace, with either one fuse or breaker in it - you have more to look at. You have to not only look/test in there -but you also have to check in your main panel box. That other (sub) box that has one fuse or breaker is there only by a code thing where you have to have that there if the furnace is out of sight of the main house panel box. This should be very elementary now in finding your problem, visually or with a test meter.
 
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Old 10-17-09, 01:48 PM
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Originally Posted by ecman51`
Test all the way back to the main panel box. If you have a disconnect/fuse or breaker box near the furnace, with either one fuse or breaker in it - you have more to look at. You have to not only look/test in there -but you also have to check in your main panel box. That other (sub) box that has one fuse or breaker is there only by a code thing where you have to have that there if the furnace is out of sight of the main house panel box. This should be very elementary now in finding your problem, visually or with a test meter.
There isn't a breaker box box next to the furnace, but there is a box with one breaker in it next to the fuse box, both located in what we call the utility room beacuse it has the water heater in it also. The breaker is not kicked to the off position so I didn't consider it might have anything to do with the furnace. Thought it was for the dryer? Since we still have the fuse box, any hint on what to check there? Has glass and cartridges. Bad cartridge?
 
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Old 10-17-09, 02:18 PM
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If for an electric dryer, it will either have two 30 amp fuses next to each other in the box, or one circuit breaker that is twice as wide as a single one, and it will say 30 on the switch part.

In the main panel box, it would be one of the glass (likely 15 amp)fuses. You need to remove the one for the furnace, and set your test meter to ohms, and test to see if it has continuity, like it is supposed to. (You test between the bottom metal and side metal threads, or a piece of springy metal on the side of the fuse, when testing).
 
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Old 10-17-09, 02:37 PM
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Originally Posted by ecman51`
If for an electric dryer, it will either have two 30 amp fuses next to each other in the box, or one circuit breaker that is twice as wide as a single one, and it will say 30 on the switch part.

In the main panel box, it would be one of the glass (likely 15 amp)fuses. You need to remove the one for the furnace, and set your test meter to ohms, and test to see if it has continuity, like it is supposed to. (You test between the bottom metal and side metal threads, or a piece of springy metal on the side of the fuse, when testing).
Went to check - the breaker is twice as wide and says 30 on the switch so this box is for the dryer then.

Opened the fuse box and viewed the glass fuses....
All seem to be OK, no broken filiment(excuse the spelling).
Wouldn't ya know it - the one for the furnace isn't named on the legend found on the inside of the fuse box door!!! Guess I'll have to check the ones not listed. At least this way I get to find out whats what and list them myself....
This will take a bit of time so I'll get to now.
Glad you're here, ecman51.
 
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Old 10-17-09, 02:51 PM
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When you identify which is for the furnace, then also test the fuse socket at the base, by switching to ac volts on your meter, and test between the bottom metal and to ground. (Note that testing between base and threaded side may not work unless something is turned on and current can progress through a resistor to neutral!) We can't take anything for granted. I have ran into bad fuse socket connections on such panel boxes already and have had to fix. I've come across about everything you can imagine regarding working with housing from 1860's(maybe earlier, even) to present housing on a daily basis.

I'm glad I'm here, too.
 
 

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