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Author Topic: Lennox Gas Furnace - Frozen Spark Plug  (Read 4442 times)

Offline rockinrobin

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Lennox Gas Furnace - Frozen Spark Plug
« on: November 11, 2014, 09:17:58 PM »

My mother had an AC Repair Tech that came out today but he couldn't remove the original spark plug in a 23 year old Lennox Gas Furnace and he's suppose to be back tomorrow with a new plug.
I told her to have him use Rust-Buster (if available) or PB Blaster when he comes back.

Meanwhile, does anyone have any other idea's on how to remove the old Spark Plug?

Offline tgoods

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Re: Lennox Gas Furnace - Frozen Spark Plug
« Reply #1 on: November 15, 2014, 11:17:40 PM »
Heat.

Offline rockinrobin

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Re: Lennox Gas Furnace - Frozen Spark Plug
« Reply #2 on: November 16, 2014, 12:26:22 PM »
Heat.
Do you mean a Heat Gun?
I found the Service Manual and it says to use the Lennox spark plug/sensor removal tool (p/n  20H43) but this tool cost $200.
It's a Lennox Pulse 21 Gas Furnace Model# G21V5-100-3

Offline mz3own

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Re: Lennox Gas Furnace - Frozen Spark Plug
« Reply #3 on: November 16, 2014, 03:17:10 PM »
if it's a spark plug wouldn't a standard sparkplug socket work for it? Based on car background, adding heat isn't the ideal way because you are most likely dealing with dissimilar metals and adding heat to that will just lock them in. Try let it cool off first. Then try a bit of canned air held upside down to further cool the threads. Then tighten, yes tighten the spark plug just a touch. Then try to loosen
« Last Edit: November 16, 2014, 03:22:26 PM by keithvibe »

Offline schleifha

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Re: Lennox Gas Furnace - Frozen Spark Plug
« Reply #4 on: February 04, 2015, 06:44:16 PM »
First and foremost did they do a full pressure test on the heat exchanger? In the last 2 years I have probably changed out 20 of those furnaces! If they havent pressure tested it first i would make them do that if they dont know how tell them to leave! Get a true lennox tech to come out and do them.  If they have done it and it is good them move on to the spark plug.  On getting them out it can be a real pain and if they dont come out well your kinda S.O.L. They make them super fun to work on beings how you have to have kind of a special tool to get in there in the first place and you cant see what you are doing. 

Offline schleifha

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Re: Lennox Gas Furnace - Frozen Spark Plug
« Reply #5 on: February 04, 2015, 06:47:10 PM »
Heck i didnt see how long ago this one was even replyed on just saw it was "new" sorry for waking up an old dead thread!

 

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