Lennox G21Q Issue - HVAC - DIY Chatroom Home Improvement Forum

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


Thread Tools Display Modes
Old 11-24-2008, 01:14 PM   #1
Join Date: Nov 2008
Posts: 1
Rewards Points: 10

Lennox G21Q issue

I have a Lennox G21Q4/5-100-3 that is giving me a little trouble.

This problem went unsolved last year and we basically went without heat - there were busted water pipes and cold hands.

I've been looking at this issue on and off for the last two weeks. I have cleaned flapper assembly and replaced flapper and checked intake/exhaust for blockage. At this point, I believe the issue it that the furnace gets started and the blower may or may not start and, if it does start, shuts off when it shouldn't. I found the blower motor to have a ton of hair/crap caked in the side where the electric connects to it. Cleaned this all up but the problem persists. When the blower goes to start or when it cuts out prematurely there is usually a noticeable zzzt-zzzt-zzzt sound and I have seen a small electrical arc (not sure if that's correct terminology). I thought it was the transformer that was the problem (p/n 78H5501), but after seeing the electrical arc on what I think is a blower control (Heatcraft FTC5-EH04), I think that's it. I can usually bump this unit, or the red wire that connects to it, (sometimes zzzt-zzzt-zzzt) and the blower will fire up and usually run until the thermostat setting is reached (doesn't matter what the temp reading is on the limit control). After that, whos to say.

Next I'm going to reseat all of the connections on the blower control, this time with the power off so I don't get zapped. But otherwise I'm looking for some insight as to what going on here and if replacing the blower control is recommended (price?).

A couple of side questions:
1. Does the limit control read actual temperature in the heat exchange compartment?
2. What is the function of the expansion tank?
3. Is the heat exchanger or the furnace itself being 'beat on' by it continually reaching the cut-off point because of this blower issue?



Last edited by gotzapped; 11-24-2008 at 03:12 PM.
gotzapped is offline   Reply With Quote
Old 11-25-2008, 02:04 AM   #2
Join Date: Nov 2008
Location: palm coast fl
Posts: 588
Rewards Points: 500

i tryed to look at a parts breakdown for that unit and it was not helpful really. it sounds like the thing your banging on is some kind of relay and just from what your describeing id say replace it

1- yes
2- to reduce noise (not sure totally)
3- like your car continueally o/h its not the best thing for it
4- lennox sucks (sorry did i say that out loud)


Last edited by kennzz05; 11-25-2008 at 02:07 AM.
kennzz05 is offline   Reply With Quote
Old 11-25-2008, 02:28 AM   #3
An old Tradesmen
Join Date: Oct 2008
Location: Somewhere
Posts: 34,577
Rewards Points: 8,144

It needs a thorough check out by a "Qualified" Lennox tech.
beenthere is offline   Reply With Quote

g21q , lennox

Thread Tools
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
Cable issue or wiring issue? Duchey Electrical 57 12-15-2008 01:34 PM
For all you Lennox owners ibwahooka HVAC 9 11-23-2008 04:06 AM
Fireplace framing/tile issue robdville Building & Construction 13 11-14-2008 07:14 AM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1