Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 10-23-2012, 12:02 PM   #1
Newbie
 
Join Date: Oct 2012
Posts: 4
Rewards Points: 0
Share |
Default

Lennox furnace issues


Hi all,

We have a Lennox G23Q3/4-125-4 furnace. A couple of weeks ago it stopped blowing. My wife and I took out the owner's manual and were able to determine that the bcc was bad. We could tell that it was overheating in the chamber which is why it was shutting down and following the flowchart, there was no voltage between N1 and A (though I assumed at the time that N1 was the left most neutral terminal which I'm thinking may have been wrong).

So we replaced the bcc, the old one definitely had some burn marks on the back and the furnace is blowing air now. But it still shuts off before reaching temp. It will blow for about 4 or 5 minutes then shut off. I can see 24 volts across the gauge that triggers the auto shut off. The blower keeps blowing though and 30 seconds later it kicks back on again.

So end result is that our house is being warmed which is good. But we'd like to know why it keeps shutting off periodically. Is this normal? If not, what can we do? It seems there are ways to change the blower speed but we can't seem to find where to adjust this.

Thanks!

griztown is offline   Reply With Quote
Old 10-23-2012, 04:36 PM   #2
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 0
Default

Lennox furnace issues


Check the simple things first. Filter clean and registers open? The next step would be to check the temp on the limit and measure the air temp in the mounting hole to see if the limit was damaged from over heating. Take a look at the bottom side of the AC coil,if you have AC, and make sure it's clean. Beyond that you'll need a multimeter to check blower motor amps and capacitor.

Marty S. is offline   Reply With Quote
The Following User Says Thank You to Marty S. For This Useful Post:
ben's plumbing (10-23-2012)
Old 10-23-2012, 08:59 PM   #3
Newbie
 
Join Date: Oct 2012
Posts: 4
Rewards Points: 0
Default

Lennox furnace issues


Quote:
Originally Posted by Marty S. View Post
Check the simple things first. Filter clean and registers open? The next step would be to check the temp on the limit and measure the air temp in the mounting hole to see if the limit was damaged from over heating. Take a look at the bottom side of the AC coil,if you have AC, and make sure it's clean. Beyond that you'll need a multimeter to check blower motor amps and capacitor.
Thanks Marty, we had the furnace serviced just a few weeks before it died so the filters should be clean.

I'll try and run through some of these steps and let you know.
griztown is offline   Reply With Quote
Old 10-26-2012, 07:56 PM   #4
Newbie
 
Join Date: Oct 2012
Posts: 4
Rewards Points: 0
Default

Lennox furnace issues


To measure the temperature in the mounting hole, are you suggesting we take out the limit and measure the temperature there? I do have a multimeter fortunately, what would I be looking for at the capacitor and blower? Just to make sure they have 120 volts? Wouldn't you assume that I wouldn't feel any hot air blowing through my vents if there was a problem there?

Thanks!
griztown is offline   Reply With Quote
Old 10-27-2012, 07:58 AM   #5
Member
 
Join Date: Oct 2009
Location: Nebraska
Posts: 2,362
Rewards Points: 0
Default

Lennox furnace issues


The capacitor will have a mfd rating,check with the meter that it's correct. A weak capacitor makes the motor spin too slow.If your meter doesn't have a mfd scale... take the amps of a capacitor wire(either one), measure the voltage with a lead on both sides of the capacitor. (Amps x 2652)/volts=mfd.
Motors have rated amps printed on them,should run under that.BTW the blower speeds are adjusted at the motor. The spot next to the white neutral is high and each spot farther away is a lower speed.
Yes take the limit out and measure the temp at the spot where the sensor part of the limit would be. Some of the G23's had a 3" stem on the limit and others used a disk. Either way if the temp never gets to the limit trip range then you know the limit is weak. Simple process of elimination.
Marty S. is offline   Reply With Quote
The Following User Says Thank You to Marty S. For This Useful Post:
how (10-27-2012)
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Natural Gas Cost For Furnace 1 Hour Run Time hammerlane HVAC 15 11-11-2013 10:34 AM
Lennox Pulse furnace pau HVAC 4 10-11-2011 07:59 PM
Smoke and Vent on a New Lennox Furnace Handymannabee HVAC 3 04-13-2011 03:46 PM
Portable generator and Lennox furnace joshbloomberg Electrical 7 02-10-2010 10:25 PM
RE: Loud and Noisy Furnace - LENNOX 90UGF Please help. amilayajr HVAC 10 10-11-2009 06:57 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.