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Old 07-15-2009, 06:06 PM   #16
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Lennox G20 Series - Bad blower board - or is it more?


ABout the fuse:

My secondary side is 24V.

is the 40V/24V inline fuse the one I ask for??

Not quite sure what I'm supposed to be getting here.

Took me a while to understant what 'former meant.

Not as "old Hat" as I thought.

Richard

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Old 07-15-2009, 08:17 PM   #17
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Lennox G20 Series - Bad blower board - or is it more?


Ok,

The secondary side of the transformer says 24V 30VA. That seems high for such a little Circuit blower board?? ...or is VA different from amps??

I'm finally getting IT here. So, 40VA/24V. Sorry, I'm a bit slow (too - Dracula reference).

I was at the hardware store and the locals told me to get an amp rating and come on back. Only they didn't have a method for placing the fuse in-line.

The local auto parts store does have in-line fuses. Thick wires. Before I wire nut a 40 amp fuse to each of the two 24 lines I think I'll call my local appliance part store and ask for the correct fuse and methodology for installation. I am assuming the fuse goes between the board and the 'former. Please correct me if I'm wrong. Does it have to be BOTH 24v lines exiting the 'former??

Yup, ignorant. (Keep your fangs to your self Dracula)

Thanks for your upcoming advise. Almost there!

Really, Thanks a ton!

Richard
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Old 07-15-2009, 08:22 PM   #18
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Lennox G20 Series - Bad blower board - or is it more?


Go back to the auto store and ask for a spade inline fuse with 14 or 16 agw. Install it in the 24 vac circuit off the transformer before it goes to the board.

For the fuse just usa a automotive 3 amp and you will be fine


Most board of the day will have either a 3 or 5 amp fuse. I use 3 amp. I buy the inline fuse adapter at radio shack and the fuses at an automotive store in bulk.
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Old 07-15-2009, 08:41 PM   #19
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Lennox G20 Series - Bad blower board - or is it more?


Thanks Plumber,

So it sounds like Just one of the two wires coming out needs to get fused???????

Yoyizit, is the "40/24 = ~1.5A slow blow" A better choice?

I'm mostly learning here now as I realize that either solution is better than the "lack of fuse" I currently have.

It was 97 outside today, thanks guys for getting me this far. The house is a single level and is cooling off nicely! I'll wait til tomorrow to finalize this restoration.

So again, fuse 1 line or both 24V lines?????

Respectfully submitted,

Richard
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Old 07-15-2009, 08:47 PM   #20
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Lennox G20 Series - Bad blower board - or is it more?


One line.

Also need to figure out which is power and ground of the transformer and install in the power side.

1.5 slow is OK but the 3 amp will do the same thing. Then if it blowes in the middle of the night your car may have a spare.

Just remember this KISS

K - Keep
I - It
S - Simple
S - Stupid

Sometimes it does get more complicated but with this just keep it simple.

Round fuse are not very common and can be hard to find sometimes
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Old 07-15-2009, 08:55 PM   #21
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Lennox G20 Series - Bad blower board - or is it more?


If he replaced the transformer with an OEM he will need to know which color is hot because Lennox transformers of that vintage do not show a reading from 24 v hot to ground because the way they wound the primary and secondary.
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Old 07-15-2009, 09:02 PM   #22
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Lennox G20 Series - Bad blower board - or is it more?


Clover

Could he use a DVOM and from one lead go to one of the secondary wire and the other lead go to the transformer block

I have never encountered this tansformer you talk of.
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Old 07-15-2009, 09:23 PM   #23
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Lennox G20 Series - Bad blower board - or is it more?


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Clover

Could he use a DVOM and from one lead go to one of the secondary wire and the other lead go to the transformer block

I have never encountered this tansformer you talk of.
Don't know. Never tried that.But if it works it will tell which is hot. I just made sure I had 24v across the secondary and made sure I had the color right. But if he changed it and got a standard transformer it won't make any difference,
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Old 07-15-2009, 09:30 PM   #24
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Lennox G20 Series - Bad blower board - or is it more?


Oh guys,

Ignorance lead me to a NON-OEM transformer at my local Appliance parts store. I'm thinking, :A transformer is a transformer."

Well, Did I get lucky???? It is running. But.....

So, I bought a class 2 40VA transformer PRI 120V SEC 24V.

So, if it is non-lennox will there be a reading... now. So am I looking for one side to show voltage and one to not??

While I'm a firm believer in the KISS menatality, I'm starting to feel like I'm fixing something that ain't broke. None-the-less, I do INTEND to get a fuse their to prevent future woes! Provided I can figure out what's best.

So, check for voltage and fuse one side?

Richard
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Old 07-15-2009, 09:32 PM   #25
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Lennox G20 Series - Bad blower board - or is it more?


So am I looking for one side to show voltage and one to not??

True

And put the fuse in the one that shows voltage
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Old 07-15-2009, 09:38 PM   #26
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Lennox G20 Series - Bad blower board - or is it more?


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So am I looking for one side to show voltage and one to not??

True

And put the fuse in the one that shows voltage

Yeah you're ok. That OEM was just another way lennox keeps everybody in the dark about about the true specs on their parts.

They sell a motor that says 3/4 hp on it and it really is almost or is a full horsepower.
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Old 07-15-2009, 09:38 PM   #27
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Lennox G20 Series - Bad blower board - or is it more?


Quote:
Originally Posted by inn8pwr View Post
Nice.

So are these in line fuses??

BTW:

I went ahead and put her back together and the house is cooling as we speak.

Thanks for the help. Looks like I can avoid the expense of a blower board for now.

I will look into the 40V/24V inline fuses.... if you meant inline.

Thanks,

Richard
http://www.rd.com/images/tfhimport/2...g003_size2.jpg
So all it was was an open 'former secondary winding? You got away lucky.

I guess if you fuse the primary 120v winding then both windings and the upstream wiring are protected. 40VA/120v = 1/3A.

Last edited by Yoyizit; 07-15-2009 at 09:47 PM.
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Old 07-15-2009, 09:41 PM   #28
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Lennox G20 Series - Bad blower board - or is it more?


Quote:
Originally Posted by Yoyizit View Post
40VA was just an example. Fuse it depending on the 'former rating.
http://www.rd.com/images/tfhimport/2...g003_size2.jpg
So all it was was an open 'former secondary winding? You got away lucky.

He ain't outta the dark yet. He's gotta find out why it blew.
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Old 07-15-2009, 09:58 PM   #29
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Lennox G20 Series - Bad blower board - or is it more?


I am hoping the reason it blew was the water leak down the thermostat wire etc.

I'm hoping that all water residue is gone.

However, the fact that the system worked for 1 week and then DIED AFTER I solved the water problem is still mystery. A weakened 'former decidedd to kick the bucket on it's own time??

The system has always RAN fine once on, it just WON'T start a new cycle when prompted by the thermostat (historiclly speaking here - read the full thread for detail).

FYI: My old thermostat was a 4 wire and the new thermostat accommodates the system fine - with 4 wires.

All wire connections to AC and internals look fine (what's visualized easily). The thermostat wire is new.

Actually, I need to get the electronic air cleaner working. I imagine that would be good for the seasonal allergens in the air??? I'll bet it's the power supply in that puppy that died.... perhaps another thread??

I'll get to the Transformer fuse tomorrow and let you know what I find!

Thanks for all the help, and for speaking in Lay-persons terms.

Hmmmm, I wonder if there is a circuit that spikes when the thermostat tells the system to turn off????????????? Wish I had the fuse on there now!

Thanks again,

Richard
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Old 07-15-2009, 10:02 PM   #30
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Lennox G20 Series - Bad blower board - or is it more?


Quote:
Originally Posted by inn8pwr View Post
I am hoping the reason it blew was the water leak down the thermostat wire etc.

I'm hoping that all water residue is gone.

However, the fact that the system worked for 1 week and then DIED AFTER I solved the water problem is still mystery. A weakened 'former decidedd to kick the bucket on it's own time??

The system has always RAN fine once on, it just WON'T start a new cycle when prompted by the thermostat (historiclly speaking here - read the full thread for detail).

FYI: My old thermostat was a 4 wire and the new thermostat accommodates the system fine - with 4 wires.

All wire connections to AC and internals look fine (what's visualized easily). The thermostat wire is new.

Actually, I need to get the electronic air cleaner working. I imagine that would be good for the seasonal allergens in the air??? I'll bet it's the power supply in that puppy that died.... perhaps another thread??

I'll get to the Transformer fuse tomorrow and let you know what I find!

Thanks for all the help, and for speaking in Lay-persons terms.

Hmmmm, I wonder if there is a circuit that spikes when the thermostat tells the system to turn off????????????? Wish I had the fuse on there now!

Thanks again,

Richard

The most common reason for blown transformers is homosexual electrons

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