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    chuckb's Avatar
    chuckb Posts: 15, Reputation: 1
    New Member

    Dec 11, 2007, 09:54 PM
    Self test OK, but no heat from day&night forced air furnace
    So this morning I cleaned the filters and turned power off to the furnace. Now power is back on, self test passes (inducer, igniter, humidifier relay (no humidifier hooked up), blower high, blower low), but when I put it back in operation heat does not come on - just th 'inducer.' the igniter does not try and come on under normal (not test) operation.

    Suggestions welcome, and about a year ago, I replaced the igniter.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert

    Dec 11, 2007, 10:59 PM
    Take it apart like you said you did in another post. You will figure it out.
    That's right you need a ignitor.
    chuckb's Avatar
    chuckb Posts: 15, Reputation: 1
    New Member

    Dec 11, 2007, 11:12 PM
    OK, so I measured some 50 ohms on the igniter - seems high, but then, that's 2+ amps and I did see it glow orange during the test operation.

    I'm confused on what happens when. I looked at various post to do with fan limit (switch closed - should it open at some normal op point?), some vacuum thing (N.O. contact, never gets any AC on it - is that later in the startup sequence?).

    What does it take for the igniter to come on - what switches (besides the interlock switch on the cover) need to be open/closed, etc. The PC board has lots of stuff on it, including test points, but I don't have a sequence or a diagram to go with.

    chuckb's Avatar
    chuckb Posts: 15, Reputation: 1
    New Member

    Dec 11, 2007, 11:58 PM
    OK, I mucked with things and found a temp switch that was not closed - it measured 25VAC on it when it was not closed. I took it off, measured it and saw that it had a center reset switch which I pushed. The switch is similar in appearance to the two by the intake jets(?), but it is on the upper side, by the exhaust (mine's a downdraft?) furnace - warmed air blows down into the plenum, which is in the crawlspace.

    I'm still expecting pg&e - one week turnaround to check things out.

    I wonder what temps those temp switches sense. Oh, and I'd tested the pressure switch with my own breath - cute switch, but I'm not sure what it does in the setup.

    Interesting stuff. Interesting board.

    I wonder why they don't post schematics inside? Oh, and there was some other switch to do with the blower on the housing - never found it, but there's a sticker that talks about it.

    Lastly, I heard that there is some lawsuit against day&night, which I hear is out of business.

    What's up with that?

    Enjoy it while you can,
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert

    Dec 12, 2007, 02:51 AM
    Day and Night out of business. You got to be kidding.

    Carrier,Bryant, Day and Night are all the same company. Plus they make generic brands for other brand names. One of the largest HVAC corporations in the world. They are part of the UTC group. United Technologies Corp.

    Share holder value increase of 337% from 1997 to 2006. My stock did very well!

    In 2006 they did 47.8 Billion dollars worth of business. Not to shabby!


    Carrier heating and air conditioning systems
    Hamilton Sundstrand aerospace and industrial systems
    Otis elevators and escalators
    Pratt & Whitney aircraft engines
    Sikorsky helicopters
    UTC Fire & Security protection services
    UTC Power
    United Technologies Research Center

    20th largest U.S. manufacturer (2006 list, Industry Week)
    43rd largest U.S. corporation (2006 list, Fortune)
    55th largest publicly held manufacturer in the world (2006 list, Industry Week)
    126th largest in the world (2006 Global 500 list, Fortune)
    Named "Most Admired" aerospace and defense company (2001-2006 lists, Fortune)

    215,000 employees (2006)
    47th largest employer in the world (2006 Global 500 list, Fortune)

    $47.8 billion (2006)

    $6.4 billion (2006)

    Commercial & industrial 63%
    Commercial aerospace 21%
    Military aerospace & space 16%

    60% of total revenues (2006)

    Over 4,000 locations in approximately 62 countries; UTC does business in approximately 180 countries.

    $3.7 billion or $3.71 per share (2006)

    $47 billion (as of Dec. 31, 2006)

    $3.2 billion (2006)

    $954 million (2006)
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert

    Dec 12, 2007, 02:54 AM
    Weak limit switch (test or replace)
    Lack of proper air flow (check all openings)
    Gas pressure higher than acceptable for your unit. (adjust)
    chuckb's Avatar
    chuckb Posts: 15, Reputation: 1
    New Member

    Dec 12, 2007, 07:36 AM
    OK, so yesterday, not finding a manual (wife's new filing system), I looked up day and night and came up with:
    Class action lawsuit (time to secure some of your gains?)
    And a 'day and night furnace' concern with a 408 phone number. I called the first, but got an eastern time zone recording referring me to their web pages. I then called the second, and asked the guy if they were manufacturers with that name, and he said that the manufacturer went out of business a while back.

    Last night I found the schematic on the back of the lower panel. It shows a yellow wire going to a couple of switches in series. It first goes to the yellow (normally open) vacuum/pressure switch) and it seems to work. Out of it comes an orange wire, firs to auxiliary limit switch that is somewhere on the big fan housing. That one appears to work (although I've not found it!) as it comes back to what the schematic calls als2 (auxuliary limit swtich two) which is the one that I reset last night. When I put things back together, the problem came back. So, last night, I decided to have a brandy and go to bed after hooking up a 1500w portable floor heater on a long fat extension cord, to thaw out whoever was frozen. This morning, it being my wife's birthday, I put it in the bathroom for her - she should be out within the hour or so...

    I then went back to the furnace. That same als2 was popped. I turned of power, manually reset it (center button) and LEFT THE BOTTOM PANEL OFF. The furnace has been working for the past 20 minutes w/o signs of a problem. I left its closet door open to keep an eye on it. It's probably not advisable to run it w/o that bottom cover that exposes als1, the igniter, the flames, etc. so, I'll turn it off shortly, once everyone thaws out.

    How does als2 work? Is it a temperature switch? Why does leaving the panel off not pop it? The only things I can think of in addition to your suggestion of replacing it are:
    1. oil fan (?) not sure where/how - old one had a little cap for oil on the shaft/bearings.
    2. the foam around the front removable panels has flaked off - is that a cause for concern/some pressure limits?

    Thanks for your help, and I'm glad I contributed to your stock gains!

    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member

    Dec 12, 2007, 07:52 AM
    Next time you have a problem, you can find a sequence likely close enough at

    Also pictures of many components.
    chuckb's Avatar
    chuckb Posts: 15, Reputation: 1
    New Member

    Dec 12, 2007, 08:02 AM
    Hey, labman. That was a good link - I checked it last night and it helped me a lot, especially the photos. I did see the limit switch right above the burners, took it out, looked at it and put it back.

    I did not see an image of what my furnace calls as the auxiliary limit switch (two of them, and they look like the same kind of switches on close to where the air goes in (venturi?) to the burners - one on each side. I'm guessing temperature, but for air?? (not coupled to metal surface) one quick disconnect on each side and a small button between, all on a round can.

    Oh, are the guide dogs, guide dogs for the blind or for some other purpose?

    Our dog is useless but otherwise great for petting, eating, laying by the fire, and keeping my skinny son warm at night,

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