Janitrol Furnace (Blower won't turn on when in the "auto" setting)


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Old 10-12-11, 05:03 PM
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Janitrol Furnace (Blower won't turn on when in the "auto" setting)

Hello everyone,

In the rehab house I bought, somebody cut a few wires in my furnace, ripped out the A/C units, destroyed the electric to the garage, ripped off the gutters and did a whole lot of other annoying damage.

Two days ago, I didn't even know how to light a pilot on a furnace, but after calling around and seeing how much places charge for service calls, I decided to do a little internet research.

The first problem was that I couldn't even get gas to the pilot. In the end, it turned out that the pilot was just clogged, but after I got that working I had to run to Lowes to buy a new thermocouple to keep it lit.

The second problem was that the Red wire for the blower had been cut, so I put that back together. Now, the blower will run continuously if put in the "ON" position on the thermostat.

The third problem, is that a blue wire which came from the left side of the Limit Switch was not connected to the transformer. After connecting this, with the pilot light working and the electric on, and the thermostat set to 6 degrees higher than the current temp, and the blower in the "AUTO" position, the burners would ignite and stay on for several minutes.



So...... Everything works now, except the blower will not come on when the thermostat has it in the "AUTO" position.



My first thought, from my research, is that it would be the Limit Control..... but here's the thing...

1) The limit control does rotate on its own when the burners are on, leading me to believe its heat censor is operational.

2) The limit control "clicks" like it's supposed to, assumedly when it reaches the set temps for blower on/off and burner off.

3) When having the electric off and using a meter, you can see that when the blower should be off the circuit is open, and if you rotate it slightly by hand and hear the click that should turn the blower on the meter beeps, signifying a closed circuit.



I'd really hate to buy a part I don't need, but I can't think of anything else that would be giving me problems here. As I stated before, I'm a complete novice when it comes to furnaces aside from my 2 day crash course, but it seems to me like the limit control should be functioning properly.

Does anybody have any ideas I could try before breaking down and calling a pro?????


THANKS!!!!!!!!
 
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Old 10-12-11, 05:07 PM
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well, your limit should be wired to the blower or relay... is it?
 
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Old 10-12-11, 05:13 PM
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Hi hvactechfw,

Yes, there is an orange and red wire to the limit as well as two white wires.

In my noviceness.......... It looks like the power goes to the upper right of the limit and the power from the upper left of the limit goes directly to the blower. So..... I'm a little confused why the blower doesn't kick on when the circuit is closed when the limit dial's middle knob temp is reached.

I assume that the limit is working and turning the burner off when the plenum reaches the "high" temp, but there may be some other fail-safe that is turning the burners off and the limit control itself doesn't do a damn thing......




Oh... and just to add... I did check the wiring behind the thermostat and the red, white, green and yellow wires are all where they should be, so I don't believe the problem is there at all. Also, these wires are all connected to the proper places on the transformer.




EDITED TO ADD:

"Relay"..... sorry.... I'm not sure what a relay is. Even if it's not the problem, I'd like to learn everything I can about a furnace while doing this. Could you explain this to me?

Thanks again!


EDIT 2:

Or just show me a link to a description that is good......

I looked it up and I know I have a relay from pics that I've seen, but I can't seem to find a good description of this part online like I have found for other parts.
 
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Old 10-12-11, 05:25 PM
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the relay will run the blower at different speeds..... when you call for fan on by the thermostat it sends a 24VAC signal through the G terminal to the relay which allows 120VAC to be applied to the blower motor. Behind the blower door there is often a schematic that, if you cant trace the wires from the limit, will show you what wires should be installed where.

Typical fan limit schematic

 
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Old 10-12-11, 05:43 PM
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There is a schematic behind the blower and, to my surprise, I can actually figure some of it out. Some of it is foggy though because wiring inside doesn't always match the color code of the schematic so I get lost on some parts. There is a learning curve here, but after a few days of looking at it, I do believe I'm starting to understand quite a bit more than the first time I looked at it.


I can tell you that I took the "hot" wire that was connected to the "R" on the transformer and put it on the "G". The only thing that this did was run the fan continuously as if the thermostat was on the "ON" position.

I'm not sure if that would help explain the problem at all.......

If not, perhaps I'm not giving enough information for you or anyone else to come up with any ideas.

Would it help if tomorrow I posted some images of the wiring in my furnace so that you might get a better picture of what I'm trying to say.

If a picture says a thousand words, it probably speaks a million words from that of a dumbass
 
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Old 10-12-11, 06:00 PM
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if you follow the wire on the fan side of the limit to the blower you need to verify power in and out of the limit by way of a volt meter.
 
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Old 10-13-11, 02:28 PM
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Unfortunately, I was borrowing a friend's multimeter and I don't have a way to test it now. I will be picking up a cheapo 120-480V Volt Meter at Lowes on Saturday and I'll get back to you about it.

We tested the continuity of the limit itself, but forgot to test if power was leaving it to the blower unit. I assume it's safe to believe that there is power to the limit because it rotates, or am I wrong about that?
 
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Old 10-13-11, 02:47 PM
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well, you would need to verify there is power in first
 
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Old 10-13-11, 03:16 PM
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So the fact that the limit dial rotates when the burners come on doesn't mean that there is sufficient power even going to the limit?

Okay. I'll test both the power in and out when I get my meter.

Thanks again
 
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Old 10-13-11, 03:24 PM
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the limit dial rotates due to the heat generated by the burners/ heat exchanger not by power.
 
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Old 10-13-11, 03:41 PM
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Great to know!

Thanks again
 
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Old 10-14-11, 12:23 PM
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Hi again,

I got it working!!!!!!

I remembered I had a cheapo unit that would light up when you touched one end to the ground and the other to the hot wire. There was indeed power going to and from the fan limit.

I traced the Red wire leaving the fan limit to behind the transformer and it was capped to another red wire going to the plug unit which has the ajoining plug for the blower in the case underneath.

The Red wire was then connected to a Green wire on the blower for some reason. I switched it so the Red traveling all the way to the blower connected to the (unused) red wire to the blower and voila!!!!!


At this point, I do believe the previous owner(s) seriously did some sabotage and it wasn't just accidental cut wires while removing the A/C units and the copper piping for the A/C. They sure weren't happy to be foreclosed on.


Anyways.... now the wires from the blower that are connected to the upper portion of he furnace are:

Red (from limit)
Black (goes into transformer box, but didn't trace it from there)
White (goes into transformer box to meet with other white ground wires which are capped)

And then there's the Brown and Brown with yellow stripe (which both come from, and go back to the blower after going through the capacitor.



Now that I've watched 2 cycles and:
1) The burners come on when I turn the desired temp on thermostat 1 degree above current temp.
2) The blower comes on at about a minute later.
3) The burners shut off when the desired temp is reached on the thermostat.
4) The blower shuts off about 3 minutes after the burners shut off.

Would you say that I've tackled the problem and that this furnace should be safe as well as operational?



BTW.... thanks for the questions. Made me think about what was going wrong and something just clicked this morning.
 
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Old 10-14-11, 02:53 PM
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operational, yes. Safe I can't say with out a pro having looked at to determine that.
 
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Old 10-14-11, 05:54 PM
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Hehe..... well.... fingers crossed than.

They charge too much
 
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Old 08-09-13, 07:05 AM
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Hello,

I just wanted to say thanks again to hvactechfw for his assistance getting my furnace working.

I've survived two relatively mild winters so far with it appearing to be fully operational and (fingers crossed) it hasn't blown up on me yet.

I'm REALLY cheap, so I haven't pushed it past about 64 degrees, and I don't think we've had any days that were sub-zero in the last two winters, so I doubt I've been putting too much strain on it. Something tells me this winter will be a bear..... I think we're due. I'm pretty confident that this unit should provide enough heat until I can afford to install a new energy efficient model.

THANKS AGAIN MAN!!!!


(My apologies if some people think it was unnecessary to bump this thread. I figure everyone likes a happy ending, and just wanted to give a shout out to the moderator who took time out of his day to help solve my problem.)
 
 

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