# no heat...help



## buhler (Oct 7, 2008)

I have a tempstar furnace which worked fine till a week ago..for a time the blower motor would make a humming sound before kicking in...now nothing. I checked the thermostat and there is no spark when you flip the mercury switch side to side. I tried the crossng w/r trick at the thermostat and on the furnace..nothing...no spark no nothing. What is the next step? new blower motor? 

Thank you 
Joe Buhler


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## hvaclover (Oct 2, 2008)

If the furnace is making no noise what ever, then it may nor have power going to it. Check breakers and fuses. Could be the power switch. Can't help you with out more info.

If you have a spark igniter than you have an older furnace.


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## Marvin Gardens (Sep 30, 2008)

One good test is to pull the motor and see if it spins freely without noise. The if you are comfortable you could plug in the motor to see if it starts okay. White is ground and any other color will work for hot. Most are black, blue and red for different speeds. Of course be real careful so that you don't short out the motor. If you have never done anything like this before then ignore my advice here.

As hvaclover said, check power first.


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## buhler (Oct 7, 2008)

i have power going to the furnace and the motor turns freely with no noise. I pulled it out and it is clean and in good looking shape. I checked the power entering the furnace and it is all good to go. I read some where about touching the w + r i think wires together right at the furnace it's self....nothing. Is it possible the motor is blown and not allowing a full circit back to the switches?


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## hvaclover (Oct 2, 2008)

Where'd go, Europe? It's been ten days since your post.Any thing is posisble. Touching r and w at furnace will blow the stat.

Need alot more info then you are supplying.

Are burners comming on?


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## buhler (Oct 7, 2008)

LOL..no sry i got sent out to work for a couple weeks just got home.:whistling2:

anyways no the burners are not coming on...it is like it is dead in the water. i checked the power where the wire enters the furnace as it is tied in with merets. Good power there..i chased the blackwire down and it runs to the swtich on the bottom panel (safety Switch i am guessing for when the panel is open) ..good power there. Then it heads under to the blower motor i believe.


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## hvaclover (Oct 2, 2008)

How old. What brand. Do you have a pilot light that is on all the time?

Do you know the efficiency (80% vents into the chimney and 90% vents thru the wall with plastic pipe).


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## Marvin Gardens (Sep 30, 2008)

buhler said:


> i have power going to the furnace and the motor turns freely with no noise. I pulled it out and it is clean and in good looking shape. I checked the power entering the furnace and it is all good to go. I read some where about touching the w + r i think wires together right at the furnace it's self....nothing. Is it possible the motor is blown and not allowing a full circit back to the switches?


Does the motor go on with power?


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## buhler (Oct 7, 2008)

not to sure of the age of the furnace but there is NOT a pilot light on all the time it comes on only when needed, it is a Tempstar and as for the percentage again guiessing up i would say 80% vents into chimney.


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## buhler (Oct 7, 2008)

Marvin Gardens said:


> Does the motor go on with power?


i will pull the tray out and try hooking the wire up directly like i read here i hope that is what you meant. I am not a pro or know anything about furnaces but i work in the oil patch and have learnt a little about power as i am the fixet guy at the rig..lol...this 110 is pretty mild compared to the 480 i deal with on the rig....so keep your fingers crossed.


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## hvaclover (Oct 2, 2008)

OK, put the door panel on the blower section and turn the stat all the way up and tell me what happens. (Where is the circuit board on this furnace)


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## buhler (Oct 7, 2008)

there is a circut board on the side wall of the furnace where the burners are..not to sure if this is the correct one your talking about. There is also a circut board under attched to the blower motor wall it looks like.


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## hvaclover (Oct 2, 2008)

buhler said:


> there is a circut board on the side wall of the furnace where the burners are..not to sure if this is the correct one your talking about. There is also a circut board under attched to the blower motor wall it looks like.


Check for a small automotive syle fuse on the board in the blower section.

If none hold safety switch down and check for 24 volts from r to c.

Tell me what youe find.


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## buhler (Oct 7, 2008)

there are no fuses anywhere...i removed all panels and plugs and checked inside and out. I am not getting any power in side the unit, i still have 120 going in from the swtich and the wires where it enters the furnace tho. Guess i am going to have to get on the waiting list for a furnace guy around here at 150/hr....damit


sorry forgot to say *THANK YOU* to you guys for all the help trying to trouble shoot this furnace grief for me...it is really appreciated.


~Joe


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## hvaclover (Oct 2, 2008)

buhler said:


> there are no fuses anywhere...i removed all panels and plugs and checked inside and out. I am not getting any power in side the unit, i still have 120 going in from the swtich and the wires where it enters the furnace tho. Guess i am going to have to get on the waiting list for a furnace guy around here at 150/hr....damit
> 
> 
> sorry forgot to say *THANK YOU* to you guys for all the help trying to trouble shoot this furnace grief for me...it is really appreciated.
> ...


Don't you even think of giving up! From the switch there is a J box. You may have lost the nuetral!

TRY JUMPING THE SAFETY SWITCH IF ALL ELSE FAILS


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## buhler (Oct 7, 2008)

okay i will try that real quick i will let you know what is on the jbox so you can advise me which 2 to use to jump it. I am asuming you mean the panel the power wires are going to after they come from the safety switch on the lower door?


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## hvaclover (Oct 2, 2008)

buhler said:


> okay i will try that real quick i will let you know what is on the jbox so you can advise me which 2 to use to jump it. I am asuming you mean the panel the power wires are going to after they come from the safety switch on the lower door?


NO! CHECK J BOX FOR LOOSE NUETRAL (WHITE WIRE).

tHE PUSH BUTTON ON THE BLOWER SECTION THE BOTTOM PANEL.

REMOVE THE WIRES FROM THE SWITCH AND JOIN THE FEMALE END CONNECTORS WITH A PIECE OF METAL OR WIRE.


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## buhler (Oct 7, 2008)

Okay here is where the wires run to..from the safety switch they go to a box, the name on the box is "Heatcraft" model # FTC5-EH01 , on the right hand side of the box at the top it has a wire at a plug that says "Limit" , then below that on the right hand side it says "Valve". On the left hand side at the top it says "COM" and below that it says "24 vac". In the center there is 2 wires going to 2 plugs with a label over both saying "Blower" 1 goes to a plug labeled "com" and 1 goes to a plug labed "NO". From there they go up to the top of the furnace to another box it is a "Honeywell" along the right hand side of that box there are 7 wires and from the top it says:

Spark no number
TH-W #7
24V #6
24V GRD #5
Burner GRD #4
PV #3
MV/PV #2
MV #1

does that help you any?


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## hvaclover (Oct 2, 2008)

THOSE ARE THE CONTROLS we'll get to those.

Listen careful now: the switch on the outside of the furnace that shuts off power, should look like a light switch. Do you have a switch like that to turn power on and off to furnace?


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## buhler (Oct 7, 2008)

yes i do..there is power to there and past it to the furnace


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## hvaclover (Oct 2, 2008)

buhler said:


> yes i do..there is power to there and past it to the furnace


 
OK, the wires from the swich attach to the furnace power wire, locate the spot where the switch wires join up with the furnace wires.


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## buhler (Oct 7, 2008)

Okay i taced the wires into the furnace..they join up inside the furnace at the top left hand side..there they are just tied to 2 other black/white wires..they go down and into a panel by the lower motor. The white wire splits..one end goes to what looks like a coil of some sort and the other wire goes to a plug that leaves that box and heads to the motor. The black wire also splits when it enter the box...1 goes to the same coil as the white on did and the other goes to the back of a 7 wire plug area.


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## hvaclover (Oct 2, 2008)

buhler said:


> Okay i taced the wires into the furnace*..they join* *up inside the furnace at the top left hand side*..there they are just tied to 2 other black/white wires..they go down and into a panel by the lower motor. The white wire splits..one end goes to what looks like a coil of some sort and the other wire goes to a plug that leaves that box and heads to the motor. The black wire also splits when it enter the box...1 goes to the same coil as the white on did and the other goes to the back of a 7 wire plug area.


 Are thy joined with wire nutS?


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## buhler (Oct 7, 2008)

with merets or i guess wire nuts..(yellow)..they both are tied with merets and head down into the furnace. The white goes straight to the lower panel, but the black of course goes to the safety panel switch and then to the lower panel also. I have good power to that point i know for sure(on the black that is)


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## hvaclover (Oct 2, 2008)

Turn the light switch on the furnace off. Remove the wire nut (they should unscrew).

Once you have the wires from the switch disconnected turn the switch back, check across the black and white wire. Should Be 120 volts.

Make sure of the voltage and tell me what it reads. Before you answer I want you to check the black wire from the switch to ground and tell me what it is .


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## buhler (Oct 7, 2008)

it is 120V....


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## hvaclover (Oct 2, 2008)

Reconnect the wires.

In the blower section is there a metal box with the the letters W C R Y and R.

What we are looking for here is the theromostat wire connection.

The heat wire goes to W terminal and should be white in color.
There is also a R terminal with a red thermostat wire to it.

There is a C terminal. There should be nothing connected to it unless you have air conditioning.

Locate these and tell me.


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## buhler (Oct 7, 2008)

okay there are a ton of wires and they go as follows;

"C" white wire
"W" white wire
"R" white wire
"Y" has 2 a red and black wire going to it
"G" has a white wire

yes i have central air.

somebody has had them apart as they are all marked with duct tape on each one.


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## hvaclover (Oct 2, 2008)

Making progress now, good.

OK, these will tell a big part of the problem.

Make sure you reattach the Yellow wire nuts to the wire they came off.

Once you make sure they are on good and tight I want you to turn the light switch on the side of the furnace to "ON".

Push in the safety switch (might have to wedge it closed). Make sure the thermostat is turned all the way up.

With the safety swich pushed in check R to C. you should have 24volts.

Tell me when you do that.


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## buhler (Oct 7, 2008)

i have NOTHING, i checked the wires all are tight but no current


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## hvaclover (Oct 2, 2008)

Ok now we are going to check the transformer. Thats the big coil that the black wire from the safety swich goes to.

Is that what you see? The black wire going to the big coil?

Tell mw hat you see. I'll be here til we find out the problem for sure.


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## buhler (Oct 7, 2008)

yes the black wire goes in to the bottom of the panel and splits into 2 smaller wires..one goes to the big coil and the other end plugs into a black box with 7 plugs on it.


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## hvaclover (Oct 2, 2008)

buhler said:


> yes the black wire goes in to the bottom of the panel and splits into 2 smaller wires..one goes to the big coil and the other end plugs into a black box with 7 plugs on it.


 
The big coil is a transformer. There should also be a white wire going to the coil. It steps down 120 v to 24 v.

The 24 wires should come out of the opposit side of the transformer rom whee the black and white wire 120v went in. They will be of smaller guage and usually not white and black. Find were thes connect and see if there is 24 v present.


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## buhler (Oct 7, 2008)

found them they were blue and yellow, the blue came out and around to the white box on the front of th panel marked "24 vac", and the yellow went to the back of i believe the "C" terminal"..i got nothing ..when i tested them.


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## hvaclover (Oct 2, 2008)

OK understand one thing :I know that unit but I am no there with you. So I am condtionally saying the transformer is gone.

As long as you had power to the furnace and you pushed in the safety switch when you tested the 24 v side of the transformer and got nothing than it should be it.

I would bench test the transformer out side the furnace. If it still checks bad buy a 40va 120v to 24v transformer,

Now listen, trans former don't usally go bad on their own.

Before you you put the new one in remove all the thermostat wires from the RWYC terminals. Install the new trans. Wit the power off of course.
When you get it first turn the heat up as highe as it goes. Connect red to R terminal. 
Turn on power and check for 24v from R to C. If you HAVE 24V put white wire to W terminal.

It should fire now.

BEWEAR YOU COULD HAVE A SHORT IN THE T'STAT WIRES. CHECK EACH WIRE WITH AN AMP METER AS YOU PUT IT ON, IF THE AMPERAGE STARTS TO CLIMB OVER 1 AMP KILL THE POWER. THAT WILL BE THE WIRE WITH THE SHORT.

nOW I AM GONNA GO GET LAID AND POP SOMe PILLS I DESERVE IT.

GOOD NIGHT.


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## buhler (Oct 7, 2008)

Thank you for your time and mostly the help i know it was probaly real trying on your end to put up with my constant pestering.., that was the problem so a new transformer was 30 bucks, it is in and installed...and we are warm.:thumbup::thumbup::thumbup:

~joe


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## hvaclover (Oct 2, 2008)

No prob. That's what we're here for. Hvac guys burps co2 and fart freon we are so into this gig LOL


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## simpleman1962 (Oct 29, 2008)

Buhler
Sounds to me like you have a low voltage problem with a fuse to the transformer or the transformer itself. Find the transformer and see if you have 24v on the red/blue or yellow/blue wires from transformer. If no voltage either transformer or fuse leading to transformer (some units do not have fuses inline with transformer. 


Simpleman


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## hvaclover (Oct 2, 2008)

simpleman1962 said:


> Buhler
> Sounds to me like you have a low voltage problem with a fuse to the transformer or the transformer itself. Find the transformer and see if you have 24v on the red/blue or yellow/blue wires from transformer. If no voltage either transformer or fuse leading to transformer (some units do not have fuses inline with transformer.
> 
> 
> Simpleman


He already did that simpleman


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## milender (Nov 11, 2008)

Hi, I'm in the suburbs of Detroit also. And I have the same problems as buhler. Transformer shows 24 v. no blower, or ignitor action. Have 80s Comfortmaker electric ignition, vents thru chimney, no inducer. I've jumped red and white at thermostat, nothing. 120v to furnace OK, blower door switch held in I can hear very slight hum, I'm thinking from the transformer. Blower cage spins freely. Any thoughts, or what did buhler do? Thanks


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## hvaclover (Oct 2, 2008)

Ignition module problem, probably vent limit switch open.


Funny you should mention this right now; I was just taking inventory of parts stock and I got more parts for your furnace then I'll probably use on a service call..


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## milender (Nov 11, 2008)

Hi Thanks, Yes broken wire at the switch, reattached and I have heat, thanks. May need those parts. Hope I don't, but who knows? I'm Downriver.


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## hvaclover (Oct 2, 2008)

milender said:


> Hi Thanks, Yes broken wire at the switch, reattached and I have heat, thanks. May need those parts. Hope I don't, but who knows? I'm Downriver.


Not far...Sterling Heights.


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