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Billy
Billy, HVAC Technician
Category: HVAC
Satisfied Customers: 19657
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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I have a Janitrol Dependable Ninety-Two furnace. Tonight the

Resolved Question:

I have a Janitrol Dependable Ninety-Two furnace. Tonight the blower began to run continuously without heat. The status light on the furnace is blinking 4 times in succession, which, according to the Chart on the inside of the panel, indicates a problem with the "Open Limit Switch". The Chart says to check "main limit open" and "aux limit open".

I haven't been able to get a hold of my tech & would really like to fix the problem myself. Is that possible, and, if so, how do I do it?
Submitted: 3 years ago.
Category: HVAC
Expert:  Tom replied 3 years ago.

Tom :

Hi..sorry you're having furnace problems..

Tom :

I don't have a wiring diagram for your furnace..but I'll do my best to help..

Customer :

Hi, Tom. Thanks. It's going to be cold tonight, too.

Tom :

The first limit is the hi temp limit...usually an auto reset...

Tom :

standby while I pull up a couple of images for you ..

Tom :

The first pic is an auto reset hi limit...usually in the front of the furnace above the burners...a couple of wires attached..if it trips..the furnace blower kicks on to cool the heat exchanger...after it's cooled it should run again..

Tom :

The second one is a manual reset....it has an actual reset button...

Tom :

You will have to reset it and the power in order to make your furnace run again..

Tom :

Now the trick is locating them...sometimes there are more than one..

Tom :

It could be located around the burner compartment...sometimes they are even located on the blower housing...

Tom :

Then you have to try and figure out WHY it tripped...

Tom :

It's an indication of an unsafe condition that must be corrected..... did you check your furnace filter?

Customer :

Yes, furnace filter needs to be changed.

Tom :

Often times if the filter is plenty dirty it will not allow enough air over the heat exchanger...tripping a temperature limit switch.

Tom :

Do you want to try and locate the manual reset and try resetting it? It should click when pushed if it was tripped.

Customer :

Yes. My computer is upstairs, &, of course, the furnace is down. So it'll be a few minutes.

Tom :

No problem...take your time.

Customer :

Also, I have the power to the furnace off right now. Should it be on to reset?

Tom :

no..not necessary..


 

Customer :

OK, be right back.

Tom :

Standing by!

Customer :

Did not locate any such switches. Everything seems to be running from a circuit board.

Tom :

Ok...the switches will be plugged into the circuit board probably via a wire harness....

Tom :

let me see if I can scare up any more info...give me a couple of minutes..if I can't help I'll opt out so another tech can try to assist..

Customer :

Ok

Tom :

Ok.. no luck..I thought I had a source....

Tom :

There are limit switches in there....the trick is to locate them...I'm going to opt out and see if one of our techs is more familiar with your Janitrol....If I find something I will reply back. Tom


 

Expert:  Billy replied 3 years ago.

 

Hello,

 

Do you know where the gas valve is?

 

 

Customer: replied 3 years ago.

yes

 

Expert:  Billy replied 3 years ago.

 

Behind the gas valve on the wall is a 2"x3" rectangle flat plate with 2 wires hooked to it.

 

Do you see that plate?

 

 

Customer: replied 3 years ago.

I'll have to go look.

 

Expert:  Billy replied 3 years ago.

 

Standing by

 

 

Customer: replied 3 years ago.
I think I see what you are refering to, although the 2 white wires look more like chords.
Expert:  Billy replied 3 years ago.

 

Those are the ignitor.

 

If you give me the model number of the furnace I will send picture. I know it is the Dependable 92 series but I need model.

 

 

Customer: replied 3 years ago.

GMPN1 00-4 REV B

Expert:  Billy replied 3 years ago.

 

 

See page 3 here...look at the vertical rectangle above the burner, it is in the middle

 

http://www.alpinehomeair.com/related/LPM-01%20Install%20Instructions.pdf

 

Customer: replied 3 years ago.

Yes I have located it.

 

Expert:  Billy replied 3 years ago.

 

First easy stuff

 

Tap on that switch a couple times with power off....turn power back on and see if code is still present.

 

 

Customer: replied 3 years ago.
I already tried that. Code is still there.
Expert:  Billy replied 3 years ago.

 

remove the 2 wires and touch the tips of metal direct together..see if code persist

 

 

Customer: replied 3 years ago.
I don't understand.
Expert:  Billy replied 3 years ago.

 

There are 2 wires attached to the plate....take those 2 wires off and touch them together so the metal tips touch.

 

 

Customer: replied 3 years ago.
Touched metal on 2 wires together. Code persists.
Expert:  Billy replied 3 years ago.

 

Thank you. We are almost done.

 

Reattach the 2 wires...now...placed around the burner at the sides and top are small dime sized switches with tiny reset buttons in the center. find these and press the center button and see if one clicks

 

 

Customer: replied 3 years ago.

That worked! 4 switches around the burner - top bottom & each side. I pressed them all, didn't hear any click, but when I powered on the furnace, the blower didn't automatically go on as it had been. I turned up the t-stat &, VIOLA, the pilot kicked on the burner & we are blowing heat as I type.

 

Thank you.

Expert:  Billy replied 3 years ago.

 

Excellent.....now if it trips again you will want to get it checked. Sometimes it is a nuisance trip...but if it starts to do it every hour...call someone in to check. Thank you for your patience!

 

Billy

Billy, HVAC Technician
Category: HVAC
Satisfied Customers: 19657
Experience: Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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