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Intertherm unit replacement

Posted: Fri Dec 25, 2009 7:11 am
by homebuff
Hey Robert!
David here again.
My Stepson & family came over last night for Xmas & looked over my unit that we dicussed about it kinking on & off at random (even with the burner on) & told me as old as my unit (Manf. date 1987 Intertherm 3 ton a/c gas heat furnace MGH-055-ABWN-06) it needed to be replaced as old as it was.
So he started searching on Ebay & found some from around $400.00-$1000.00 & higher.
I found one on Ebay that was a new unit that was purchased from a dent sale store still in the carton & guranteed it to work, similar model.
Told him I could only afford one in the middle $400.00-$500.00 range.
Now that he's gone home I cannot remember what he typed in to continue searching for a unit.
I thought you might be able to help me search for the right unit for my home.
Just some search details is all I need to get started.
No need to reply today since you probably want to spend some valuble time with your family.
Thank's! David
Hope you & your family are having a great Xmas.

Re: Intertherm unit replacement

Posted: Sat Dec 26, 2009 11:58 pm
by Robert
Hi David,

I would never buy a used furnace from the internet and only a new one from a reputable dealer with a warranty.

With that said, $400 to $500 wouldn't be enough.

I would get yours inspected and if safe, use for one more year while saving to have enough to buy one that will not bite you after the sale.

As for searching help, never tried it as I don't advise it, but would think gas furnaces, mobile home furnaces, etc...


Remember, a gas furnace must be mobile home rated and any furnace must be compatible as for as blower unit with the smaller mobile home ducts.


Had a great Christmas, hope you and yours did as well.


Thanks,
Robert

Re: Intertherm unit replacement

Posted: Sun Dec 27, 2009 5:39 am
by homebuff
:) Thank you Robert
The furnace is driving me banana's kicking on & off real early in the morning.
That's when it does it the most. During the day it work's ok. It will tend to cycle on & off & can't do anything about it unless I turn it off at the main switch inside the unit & does it when the burner is lit or when the burner is not lit.
I tried the test you told someone else here on a problem he was having identical to his by removing the blue & black wire at the rocker switch & kumping them together & made no differance. Even tried jumping across them with a screwdriver on the switch terminals.
That switch test I ruled out as being the culprit.
The furnace to me looks to be in pretty good shape.
This is the first winter with the new motor I installed myself & was acting a little strange last summer too.
Maybe I wired something wrong when I installed the motor.
I went by the schematic carefully.
Did not use the added harness that came with the motor I purchaced from you.
The only thing I did not hook up was a green wire & just taped it back out of the way.
It spins up slow like it's suppost to in the wnter & speed up slowly & turns on very fast in the summer time like it's suppost to.
Do you believe that large green wire has a purpose & needs to be hooked up somewhere?
Today i'm going to go over the wiring to the motor & inside the box at the relay's & get back with you later in the day.
If you had a step by step procedure which circuits I should concentrate on with my multimeter to find a problem in the fan circuits that would most likly help me.
I'm real good with a multimeter cause I use one at work on veh''s on all range settings.
It's a fluke meter, one of the best made.
The cycling problem doing it in the early morning hours only is what's got me concerned.
When I turn the inside switch to the on the burner goes out like it's suppost to & comes on when in the auto position & the thermostat is up to where it turns the burner on.
To me there's got to be a short in the fan circuit alone or the limit switches are defective.
Your prices on the limit switches are a bit high for me but the rocker switch is reasonably priced.
My theory on the limit switches is the contacts inside are maybe burn't & not contacting good enough & makes it trip to often.
Thank's & sorry to bother you & have a great remaining weekend.

Re: Intertherm unit replacement

Posted: Tue Dec 29, 2009 1:25 am
by Robert
Hi David,

The only step by step is the email one on one for $20 fee.


Don't know what else can be done from here.



Take care and best wishes,
Robert

Re: Intertherm unit replacement

Posted: Tue Dec 29, 2009 6:00 am
by homebuff
:D Good morning Robert
Hope your getting yourself all set up for New Years.
This morning I woke up out of a dead sleep & I was lying there & it was cold in the house.
When all of a sudden the fan just came on for about 5 seconds then went off & never came back on.
The furnace was not on ether cause I can usually hear it from the living room where I was sleeping.
Wife got up & set the thermostat up some & the burner kicked on & as alway's it came on & started heating the house up like it's suppost to.
Now that's crazy.
I'm still considering on getting a limit switch soon.
I'll see what I can do about the One On One procedure soon & maybe we can get this thing figured out.
You & your family have a Happy New Year
Have to wait till at least Thurs or Fri to get the money.
Things are somewhat tight around here for now.
Have a great one. :wink:
David

Re: Intertherm unit replacement

Posted: Tue Dec 29, 2009 11:57 am
by Robert
Hi David,

Sounds good, holler if you need anything.


Happy New Year !!



Take care and best wishes,
Robert

Re: Intertherm unit replacement

Posted: Tue Jan 05, 2010 8:20 am
by homebuff
:D Morning Robert
The crazy unit has been working ok in the daytime but the wee early mornings it cycles too often even with the burner lit.
Been really cold here down in the low teens at night.
Read on a site where some have a shield that covers the swtches keeps the incoming air from disturbing the switches.
Going to take a look at it soon to see if it has one & maybe broke off.
Said I had to remove the blower assy. to get a better look at it.
Have a great day. :wink:
David

Re: Intertherm unit replacement

Posted: Wed Jan 06, 2010 6:29 am
by Robert
Hi David,

Was gonna holler at you to give you some humor and a good laugh in all this. You should know by now how I feel about Hunter t-stats, LOL.

We have two homes right now, heat went out in old home and weather is bad here, so needed heat to protect water pipes there.


After troubleshooting during late night doing work over there, found a bad t-stat as problem and it was a new t-stat.

Being as it was 1AM, only place open was Wally World as I do not carry t-stats on my van.

The ONLY t-stat they had that would work for my furnace was a $20 Hunter. It is now installed in my old home.

Hardest thing hvac I ever had to do, LOL. :lol:

Some of the furnaces have the shields over the fan switch, but not all.

WHEN it cycles, test both terminals of fan switch for 120vac. IF it is there on one side , but not there on the other, then you know the fan switch is tripping.

IF you haven't replaced it yet, do so.

IF you have, then look for signs of a broken off shield over fan switch and be sure fan switch and limit are not in opposite locations.

Some furnaces have them reversed and limit is under a shield, if that is the case, reverse the locations.

IF neither of those conditions are seen, then probably need to go to another fan switch with slightly higher differential in on/off temps for switch.


Thanks,
Robert

Re: Intertherm unit replacement

Posted: Wed Jan 06, 2010 8:04 am
by homebuff
:lol: Thank's for that bit of humour Robert I needed that after the eposode I had last night
You wouldn't have wanted to be around me last night for sure cause I got really mad at it from cycling off & on constantly, I mean contantly!!! :evil:
I layed there as long as I could then got up & went & jerked the Hunter off the wall :twisted: but it was not controlling the heat since I had switched the 2 heat wires a few weeks ago to the 2 wire old thermostat on the other end of house, so I ruled out the Hunter all together.
Thought it might have been causing some problems with the other wires on the thermostat.
It plugs right into some pins & easy to remove & I removed it real fast.
Went & layed back down hoping it would stop the nagging cycling but it wouldn't.
Got up & cursed a little & went & hit the fan cage with my fist hard & dented it in a little.
My Wife hollored stop that!! it's not going to help getting mad.
I know anger is not the answer but I was real mad & asked the Lord to forgive me.
I'll check that voltage tonight when I get home & rewire the 2 wires together like you had told someone else to do to rule out the switch which I had already done that before & made no differance.
The 3 sections 3 ft in sq. of underbelly material that I had removed to repair some leaky pipes, by the way are still there & have not got around to repairing the holes, could it have some affect on controlling the heat in the flooring keeping to duct work too cold.
How does the unit work in these cold situations?
I know it has something to do with air controll.
Thank's so very much for hanging in there with me in my time of crisis.
If you have been watching the weather lately down in our area it has been getting very very cold.
Have a frost bite warning in our area & got really cold last night too.
Not a good time to have problems with the furnace indeed.
Again thank's for the humour it really it really helped calming me down.
Keep them coming, I'll need it till I get the furnace working right & i'll give the switch a try & go ahead & purchase a new one but have to wait to get a new limit switch when I have the money.
$85.00 is a bit steep for my pocket book.
I might be able to get my Stepson to find me one a bit cheaper since he's in that business.
Never has time to come over & help this poor old boy out & not too happy with him right now.
Even my HAVAC friend wont come over.
My Stepson thnks just going ahead & replacing the unit is the easy way out & I don't think there's alot wrong with it that can't be fixed.
Too much money tied up in it already.
Has pleanty of air coming out the register's so that means I can rule out the a-coil maybe being dirty (which I have not checked yet) causing my problem?
I've babbled on too much so i'll close & hope your warmer where your at than me.
Going to work where it's warmer & hope my wife stays warm.
One good thing, the pipes are ok, thank the Lord :D
Take care. :wink:
David

Re: Intertherm unit replacement

Posted: Wed Jan 06, 2010 9:30 am
by Robert
Hey David,

You're very welcome, hang in there.



Take care and best wishes,
Robert

Re: Intertherm unit replacement

Posted: Thu Jan 07, 2010 6:24 am
by homebuff
:) Robert I need some assistance. Intertherm model MGH-055-ABWN-06
I was wondering if the limit switch part # 636174 will work in replacement of the part # 626292 or 626235 which theses are no longer availible.
Planning on purchasing the Fan switch # 631947 & a limit swtich as soon as I get my tax refund.
Tired of my furnace acting up & giving these parts a shot to see if it will correct my concern.
Give me the correct limit switch part # if the 626174 will not work.
It has the 3 terminal type setup.
If this doesn't fix it then I will be asking for your $20.00 assistance
From reading your last post, you offered no reply on the under belly holes if it would cause my problem or not. :?
Thank's :wink:
David

Re: Intertherm unit replacement

Posted: Thu Jan 07, 2010 9:59 pm
by Robert
Hi David,

What is the temp rating of the fan and the limit on your current fan&limit switch ?


No, belly openings won't cause your furnace to cycle on and off.


Thanks,
Robert

Re: Intertherm unit replacement

Posted: Fri Jan 08, 2010 5:19 am
by homebuff
:) I'll check that out today.
Must be on the frt. metal tag sticker I assume with all the other info about the furnuce & blower.
Had to leave my furnace going all night from being so cold & it never shut off but the furnace stayed lit.
Stayed pretty cozey last night as long as that thing kept going.
I was afraid to mess with the thermostat cause if I had it would have started the cycling again.
Worried about my next months electric & gas bill though.
The holes in the belly would to me have some affect though on the temps coming out of the registers cause the temps are not as hot as when it was working fine a long time ago.
Got to get those holes fixed this spring for sure.
I'll try to get the correct belly tape I need later here.
Furnace is way too important right now.
Went to some other sites for the limit switch & theirs are obsolete also for that type & alot higher than yours.
Your prices are alot more affordable than others & tend to buy what ever I will need from you in the future.
Thank's for getting back & thanks for all the support you've been giving me & sorry for being such a pest.
Down in the single digits here & the wind chill a lot worst.
David.
Have a great weekend. :wink:

Re: Intertherm unit replacement

Posted: Fri Jan 08, 2010 1:36 pm
by Robert
Hi David,

The belly holes will definitely effect the supply temps, but won't cause the constant cycling on and off.


The limit temps are printed on front of Fan & Limit Switch.

Example: L145-40 is limit and F130-30 is fan side.


Thanks,
Robert

Re: Intertherm unit replacement

Posted: Fri Jan 08, 2010 2:47 pm
by homebuff
:) Thank's Robert i'll check it out & get back with you tonight.
David