Heil Furnace driving me insane - and broke!

yuri

By disconnect switch I mean the one that supplies 120 volts to the furnace and is mounted on your wall or ceiling ( main power switch ). Those light switches are cheap and will fail with age.

What about Robin Olds. You guys should google him and read up about him, one tough smart ballzy guy. Or watch HIstory Channel - Air Aces.

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Drider75

Its hard wired with a breaker, and no switch - its a standard plug. There is 120 reaching the furnace, as there is 24V present at the transformer and control boards.

techpappy

Maybe I missed where you checked it but, is it possible the ID motor is seized/obstructed preventing rotation? From reading previous threads this can happen without blowing breakers. Just a thought.

Drider75

Nope - ID motor is fine, I jumpered 24v to it, it will run all day. One of the first things I checked...

It appears the only thing I have not done is replace the gas valve. At this point, its only another $130 so that will probably be my next try. Sure would be nice to find a service manual for this POS, I hate replacing stuff and guessing, goes against everything I've ever done as a tech person.

techpappy

You keep saying you have applied 24V to the ID fan..I thought they were all 120V...maybe this should be confirmed..

bausin

You said the inductor motor runs fine with 24VAC; although the diagram you posted shows it's 115VAC. So what voltage is it getting when it should be turning but isn't?

bausin

I really don't understand most of the suggestions in this thread. Why bother checking the pressure switch if the inducer motor is not starting? Or the gas valve?

Figure out why the inducer is not running first. Then we can get the braintrust here back to solving my problem. :-)

Drider75

Sorry, 115V, not 24. Its NOT the fan.

Drider75

This is a pretty simple furnace - there are only few things that can cause the inducer not to start:

1> Bad door interlock (checked, fine - actually its now bypassed)
2> Bad limit switch - there are 4 - all checked fine
3> Bad inducer fan - it runs fine when voltage applied to it directly
4> Bad fan timer board - replaced with new one
5> Bad connections - checked all, unseated and re-seated.

Its all been checked, we have 4 hours into this, $500 and two tech visits and the POS still does not work. Never seen anything like it.

Marty S.

Wouldn't be the first time a new part was bad out of the box.
24V between W and C...check
Limits and roll outs closed...check
board sending 120v to inducer...no
Seems like that new board is either not wired right or it's faulty

yuri

That does happen, sometimes they repackage them after some clown used it or damaged it whilst he did his parts changing routine and then took it back for a refund and lied about what he did. Did you make sure you grounded/discharged yourself B4 touching the board. Static electricity can damage them. I always touch the side of the furnace and hold it while sliding a board out of the anti static bag and periodicially touch the furnace to eliminate that hazard.

Post some closeup pics of the furnace with both doors off so I/we can see what controls it has.

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bausin

> what voltage is it getting when it should be turning but isn't?

>>Sorry, 115V, not 24. Its NOT the fan.

So does that mean you're not getting any voltage to the inducer?

danpik

Is the board puting out the 120 volts for the ID fan? Check it by unhooking the ID connection on the board and start the furnace. Measure with a volt meter and see if the ouput is working

jkv

It may be a long shot but replace that tube its the only thing you havent done sometimes they will get a hairline crack in them