I have an older coleman electric furnace (not heat pump) with a york a/c unit attached. The thermostat was replaced a few months ago and should not be the problem. My heating elements come on and off normally, but the blower will not turn on when in auto. I can turn it on manually, but the a/c runs when the blower runs even with the heat / cool switch is off. So all parts work fine, but do not work properly together. Worked fine when I went to work yesterday, but no joy when I came home last night. Help please, it's COLD in here!!

With an electric furnace, the fan should come on as soon as there is a call for heat. If it does not, I suspect a bad fan relay or if it is a multi-speed fan, the heating speed could be burned out.

Sounds plausible, but if it were the fan relay, could that cause the a/c to turn on with the blower? Here is what I have... 2 switches on the thermostat. 1 is heat / off / cool. 2 is fan manual / auto. Here is what I get...
1 heat, 2 auto = coils heat up, but no fan.
1 off, 2 auto = nothing.
1 cool, 2 auto = a/c works fine.
1 heat, 2 manual = a/c comes on.
1 off, 2 manual = a/c comes on.
1 cool, 2 manual = a/c comes on.
O.K. while writing this I double checked to see what I had with each combination just to make sure that I had the right info, and behold the first one (1 heat, 2 auto) worked the correct way. Now I know that it was not working correctly before, and the a/c still comes on when the fan is switched to manual, so something is still wrong.
The initial problem... I came home yesterday and turned up the heat, (I turn it down but not off when I go to work). It was taking a while to come on so I went to investigate... I could smell the coils so I opened up the cover and could see the coils glowing but the fan was not on and the only way I could get the fan to come on was to turn it to manual which turned on the a/c. I don't remember if the a/c and the heating coils were operating simultaneously or not.
Sorry for the long story, but want to give as much info as possible. Still thinking the fan relay? I hope so, that might be easier than calling an exorcist...
Thanks for all your help...

A/C should not come on unless stat is set for cool. Are you sure the A/C is coming on or just the fan? Is the A/C a package unit or does it use the furnace fan?

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Originally Posted by Grady White

A/C should not come on unless stat is set for cool. Are you sure the A/C is coming on or just the fan? Is the A/C a package unit or does it use the furnace fan?

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The a/c is a separate unit outside (compressor?) that uses the same blower as the furnace. When I switch the fan on manually, I can go outside and hear the unit running. I can also see the cooler panels inside near the blower start to ice up.
For now, the heat seems to be functioning normally again without explanation, and I don't plan to run the fan without heat or cool, so I guess that I am essentially back to normal. But I know that something is still not right and can expect future issues as the gremlins will inevitably act up again...
The thermostat sends the signals for heat / cool / fan on / fan off...
But what component receives and interprets these signals?
Is this a single component, or multiple, and is this likely where my problem is coming from? Also if this is where my trouble is, could it be something that is going out and could cause intermittent problems?

Sounds like your new thermostat was wired incorrectly. What color wires hook to what terminals on the stat, and what color stat wires hook to which terminals at the furnace? Let us know this, and we should be able to give info. Also, most conventional thermostats come preset for gas forced air systems. You may need to look through the stat install instructions and set your stat up for electric heat vs gas heat. Some electric units require the fan to be operated through the stat, while gas units have the fan control through the furnace itself.

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Originally Posted by mygirlsdad77

sounds like your new thermostat was wired incorrectly. What color wires hook to what terminals on the stat, and what color stat wires hook to which terminals at the furnace? Let us know this, and we should be able to give info. Also, most conventional thermostats come preset for gas forced air systems. You may need to look through the stat install instructions and set your stat up for electric heat vs gas heat. Some electric units require the fan to be operated through the stat, while gas units have the fan control through the furnace itself.

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Hmmm... Let me look at the wiring...
A little history...
I bought the house about 6 months ago. The previous owner had a York a/c unit installed outside about a year and a half ago that joins an existing older Coleman furnace and shares the same blower / duct system and thermostat.
About two months ago, I came home one evening and the heat would not come on. Turn on... Nothing... No fan (but maybe coils, I don't remember)...
I don't remember my exact thought process, but I remember thinking that the thermostat had gone awry. Removed and replaced thermostat and still had same issues. Called the folks that installed the a/c unit, hoping that there was some sort of warranty, or at least they were familiar with my system. After much testing and contemplation they pretty much agreed that it looked like a bad thermostat. Awesome people, very friendly and were not going to charge me, but I slid them $20 for gas and all were happy... Though unlikely, it looked like my stat went bad and I got a bad stat in the replacement. I returned the "bad" stat and got a bare bones, all mechanical, non-programable, Honeywell.
Everything has been working just fine for about two months then - refer to my original post...
Am thinking that maybe I have a short in the wires, or the next component in the chain is bad. It seems that I have a recurring, intermittent problem.. .
Damn gremlins...
What should be the next component downstream of the thermostat?
As for my thermostat... I have a 5 wire...
R = red
Rc = pink
W = white
Y = yellow
G = green
Jumper removed from the new thermostat that was between the R and Rc.
Please help, for I am besieged...

The fact that you have a separate wire to the "rc" makes me think you have a separate transformer in the outdoor unit? I need to know where the wires that are hooked to the stat terminate in the furnace, and out to the outdoor unit. Or, you may be better off getting a tech back in there to figure this all out. Good luck, and please let me know how things work out.

Hi, back again...
My furnace has inexplicably been working just fine for the last two weeks, until yesterday. It seems that the fan has decided to stop cycling on and off and just runs constantly now. The heating coils have decided to stop cycling on as well. I suddenly realized yesterday that the blower had been running for quite awhile and I was chilly... Must investigate... 10 degrees colder in the house than it should be and fan is running a marathon (a/c is not cycling on, but neither is the heat). Messed around with it for a minute and somehow got it to work again and house warmed back up. Went to bed last night, the blower was running and it was warmish in the house so I didn't think much of it... Wake up this morning and the blower had run all night and it was 20 degrees colder in the house than it should have been.
There are two components that are becoming suspect... The five wires that come off the thermostat all go directly to "electrical component A". There is also "electrical component B" that has some heavy duty looking wires going in from somewhere out of sight and also pretty heavy duty wires that go out and connect it to "component A". Guessing that these are electrical switches or relays of some sort. Am considering replacing them if I can ensure that I can get the proper replacement part, which does not sound easy. Any tips or ideas??
This whole adventure has been strange, I have recurring problems, but not always the same symptoms. But always the same result... IT'S COLD!!
Should I call an electrician or a priest??

Personally, I think the stinking thing is haunted.

Can you share pics of electrical components A & B?

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Originally Posted by Grady White

Personally, I think the stinking thing is haunted.

Can you share pics of electrical components A & B?

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Yes sir, truly evil spirits...
If this works then there should be 3 pics attached. The pinkish wire coming out the top of "A" goes to the thermostat. The wires that are on the right of "B" go to "A", and the wires that go to the left of "B" go into the box where my heating coils are.
I don't know if any of this helps or not, but at least you know what the beast looks like...

I got in there tonight and shook wires and felt connections, even inside the box with my heating coils. Nothing felt loose or improperly connected, but now the damn thing is working again the way that it should.

Intermittent problem sounds like a short circuit to me, but different symptoms each time does not sound like two wires crossed... Maybe an electric component that is failing internally?? I'm not an electrical genius, but it is my best uneducated guess...
Let me know if more pics would help...

"A" is the transformer which supplies control voltage (24 volts AC).
"B" is a relay. We'll get into that later but for now I'll explain "A".
R is power to the t-stat. Y is for the compressor on the A/C. W is for heat. G is for the fan on the furnace. C is common (neutral or ground) so there can be a circuit.
The Y terminal is simply a tie point to connect the yellow from the stat to a wire to the outdoor unit relay (not the same relay as "B"). I don't understand why nothing is connected to W. Is the W terminal on the stat connected?

On the stat, I have red connected to R, yellow to Y, white to W, green to G, and pink to RC.
I see on the transformer that they have red and yellow to Y, green to G, white to C, pink to R and nothing to W...
Seems strange to me...

The red from Y & the white from C most likely go to the outdoor unit for cooling.
Off the bottom of the relay in your middle picture there are two wires, one red & one brown (or tan?). Where do they go?

Yes, the red and white are separate from the other colors, I didn't see that before... They come from the dark brown wire that you can see coming from under the transformer.
Also the purple wire from the relay goes to a wirenut and changes (presto) into a black with white stripe that comes from the same place as the brown that contains the red and white. You can see these wires in the first pic...
Both the tan and red go to wirenuts and come out the other side as blue wires. The tan one ultimately connects to the transformer at G and the red one connects at C. They are the blue wires in the first picture but the wirenuts are not visible in the pic.

The more I read, the more confused I get. Just went back to read some of the early posts & discovered Red to R & Pink to Rc at the stat yet no red wire (other than the one from the piece of two lead stat wire) connected to the transformer. I presume there is no jumper between R & Rc. Correct?
May I please have the model or part number off the stat?

Oops. I goofed. Need to read more carefully. I now see there is indeed no jumper.

From what I can see in the pics, the white from the 8 lead stat wire is not connected to anything. Is that right?
The 8 lead is the wire connected to the stat?

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Originally Posted by Grady White

Oops. I goofed. Need to read more carefully. I now see there is indeed no jumper.

From what I can see in the pics, the white from the 8 lead stat wire is not connected to anything. Is that right?
The 8 lead is the wire connected to the stat?

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I apologize for the confusion, but I feel your pain...
The only wires connected to the transformer from the 8 lead are the pink, yellow, and green. The red and white wires come in from the dark brown lead. I didn't notice it before, but I think that the red and white at the stat are also separate from the 8 lead, because I have a lot of slack in them, but not in the others.
I think this pic is my stat... Honeywell YCT87N1006 The Round Heat/Cool Manual Thermostat.
It is a bare bones, non-programable, mechanical, dial type Honeywell. I have double checked that the micro-switches on the back are set correctly for my system.

Sorry to be such a pain but I need more pics. Would you please open the box behind the transformer & take a picture of what's inside?

If you can, please confirm what's going on with the two wires inside the dark brown jacket.

I had the same problem last winter. The fan wouldn't turn off. When my electric furnace guy came, he told me the "brains" of the furnace was bad and he had to replace it. Entire cost was $95 and haven't had a problem since.