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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?

Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?

The whole story:

My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I
got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?

thanks
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mm mm is offline
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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?

On Fri, 21 Mar 2008 18:10:34 -0700 (PDT), stoneattic
wrote:

Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?

The whole story:

My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I


Well, it would have been best if you had figured out what ruined the
first relay. I don't know much about how these things are wired these
days, but it's very very unlikely the relay ruined itself.

I'll bet if you check the new relay, its contract points are fused
too.

What would ruin a relay? Maybe it's a 24 volt relay but somehow 110
volts it getting to the coil?

got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?

thanks


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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?


"mm" wrote in message
...
On Fri, 21 Mar 2008 18:10:34 -0700 (PDT), stoneattic
wrote:

Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?

The whole story:

My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I


Well, it would have been best if you had figured out what ruined the
first relay. I don't know much about how these things are wired these
days, but it's very very unlikely the relay ruined itself.

I'll bet if you check the new relay, its contract points are fused
too.

What would ruin a relay? Maybe it's a 24 volt relay but somehow 110
volts it getting to the coil?


That would fry the coil, not the contacts

got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?

thanks




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Default Fan runs constantly in "Auto" but not at all in "On" onThermostat?

On Mar 21, 9:19 pm, mm wrote:
Well, it would have been best if you had figured out what ruined the
first relay. I don't know much about how these things are wired these
days, but it's very very unlikely the relay ruined itself.

I'll bet if you check the new relay, its contract points are fused
too.

What would ruin a relay? Maybe it's a 24 volt relay but somehow 110
volts it getting to the coil?



Thanks for the reply.

I don't think the new relay is fused because if the relay were fused
wouldn't you expect it to run in both "auto" and "on" like it did
before?

I checked and the relay is rated for 13.8FL @ 120 and 82.8LR @ 120.
The 24v side of it is hard wired so I can't screw that part up.
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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?


"stoneattic" wrote in message
...
Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?

The whole story:

My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I
got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?

thanks


Depending upon the make and model of the unit, something other than the
thermostat is sending power to the fan relay. Some units use a delay timer,
which could be faulty, or shunted wires at the blower could cause it




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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?

stoneattic wrote:

On Mar 21, 9:19 pm, mm wrote:

Well, it would have been best if you had figured out what ruined the
first relay. I don't know much about how these things are wired these
days, but it's very very unlikely the relay ruined itself.

I'll bet if you check the new relay, its contract points are fused
too.

What would ruin a relay? Maybe it's a 24 volt relay but somehow 110
volts it getting to the coil?




Thanks for the reply.

I don't think the new relay is fused because if the relay were fused
wouldn't you expect it to run in both "auto" and "on" like it did
before?

I checked and the relay is rated for 13.8FL @ 120 and 82.8LR @ 120.
The 24v side of it is hard wired so I can't screw that part up.

Hi,
If 'stat fan control does not have an effect, logic control board in the
furnace went bad. Try to measure 24V on that relay primary(coil) if
there is 24V all the time with G lead removed at the furnace end not at
the 'stat to rule out shorted wire. then, well?
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Zyp Zyp is offline
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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?

stoneattic wrote:
Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?

The whole story:

My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I
got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?

thanks


You're right. You messed up on the wiring. Check the units blower door for
the mfg.'s wiring diagram, and compare notes. I think you'll find you've
mis-wired the relay. And BTW, if you're not careful, you will let ALL THE
FACTORY SMOKE out of the motor and it won't run at all.

--
Zyp


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Default Fan runs constantly in "Auto" but not at all in "On" onThermostat?

On Mar 22, 3:53 pm, "Zyp" wrote:
stoneattic wrote:
Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?


The whole story:


My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I
got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?


thanks


You're right. You messed up on the wiring. Check the units blower door for
the mfg.'s wiring diagram, and compare notes. I think you'll find you've
mis-wired the relay. And BTW, if you're not careful, you will let ALL THE
FACTORY SMOKE out of the motor and it won't run at all.

--
Zyp


I'm pretty sure something is not wired right, despite my best effort.
There is no wiring diagram in the blower units door unfortunately.
Assuming I have the thermostat connected correctly...

What I've got is..
power coming in (white and black and bare "ground")
red and black on the N/O side of the fan relay, a black and a white on
the coil of the relay
a blue and a white going to the oil burner motor
a red, an orange, and a black going to the fan limit control

any ideas?
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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?


"stoneattic" wrote in message
...
On Mar 22, 3:53 pm, "Zyp" wrote:
stoneattic wrote:
Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?


The whole story:


My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I
got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?


thanks


You're right. You messed up on the wiring. Check the units blower door
for
the mfg.'s wiring diagram, and compare notes. I think you'll find you've
mis-wired the relay. And BTW, if you're not careful, you will let ALL
THE
FACTORY SMOKE out of the motor and it won't run at all.

--
Zyp


I'm pretty sure something is not wired right, despite my best effort.
There is no wiring diagram in the blower units door unfortunately.
Assuming I have the thermostat connected correctly...

What I've got is..
power coming in (white and black and bare "ground")
red and black on the N/O side of the fan relay, a black and a white on
the coil of the relay
a blue and a white going to the oil burner motor
a red, an orange, and a black going to the fan limit control

any ideas?


The colors mean little. You need a diagram. Your fan/limit control may be
defective


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Default Fan runs constantly in "Auto" but not at all in "On" onThermostat?

On Mar 22, 7:24 pm, "RBM" wrote:
"stoneattic" wrote in message

...



On Mar 22, 3:53 pm, "Zyp" wrote:
stoneattic wrote:
Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?


The whole story:


My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now I
got the weird situation described above. I picked up a new thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?


thanks


You're right. You messed up on the wiring. Check the units blower door
for
the mfg.'s wiring diagram, and compare notes. I think you'll find you've
mis-wired the relay. And BTW, if you're not careful, you will let ALL
THE
FACTORY SMOKE out of the motor and it won't run at all.


--
Zyp


I'm pretty sure something is not wired right, despite my best effort.
There is no wiring diagram in the blower units door unfortunately.
Assuming I have the thermostat connected correctly...


What I've got is..
power coming in (white and black and bare "ground")
red and black on the N/O side of the fan relay, a black and a white on
the coil of the relay
a blue and a white going to the oil burner motor
a red, an orange, and a black going to the fan limit control


any ideas?


The colors mean little. You need a diagram. Your fan/limit control may be
defective


If I had a diagram I'd be all set
There in lies the problem. There's no diagram to be found.
I'm thinking that the fan limit control may be bad as well, but until
I get it wired correctly I won't know.


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Default Fan runs constantly in "Auto" but not at all in "On" on Thermostat?


"stoneattic" wrote in message
...
On Mar 22, 7:24 pm, "RBM" wrote:
"stoneattic" wrote in message

...



On Mar 22, 3:53 pm, "Zyp" wrote:
stoneattic wrote:
Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?


The whole story:


My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that
indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now
I
got the weird situation described above. I picked up a new
thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the
wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?


thanks


You're right. You messed up on the wiring. Check the units blower
door
for
the mfg.'s wiring diagram, and compare notes. I think you'll find
you've
mis-wired the relay. And BTW, if you're not careful, you will let ALL
THE
FACTORY SMOKE out of the motor and it won't run at all.


--
Zyp


I'm pretty sure something is not wired right, despite my best effort.
There is no wiring diagram in the blower units door unfortunately.
Assuming I have the thermostat connected correctly...


What I've got is..
power coming in (white and black and bare "ground")
red and black on the N/O side of the fan relay, a black and a white on
the coil of the relay
a blue and a white going to the oil burner motor
a red, an orange, and a black going to the fan limit control


any ideas?


The colors mean little. You need a diagram. Your fan/limit control may be
defective


If I had a diagram I'd be all set
There in lies the problem. There's no diagram to be found.
I'm thinking that the fan limit control may be bad as well, but until
I get it wired correctly I won't know.


If you can identify the make and model, the manufacturer may have a diagram
on their website


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Default Fan runs constantly in "Auto" but not at all in "On" onThermostat?

On Mar 22, 9:43 pm, "RBM" wrote:
"stoneattic" wrote in message

...







On Mar 22, 7:24 pm, "RBM" wrote:
"stoneattic" wrote in message


...


On Mar 22, 3:53 pm, "Zyp" wrote:
stoneattic wrote:
Does anyone have an idea as to why the fan on my heater/AC would run
constantly when the thermostat is set to have the fan in "Auto" mode
but not run at all when in "On" mode?


The whole story:


My fan was running all the time regardless of thermostat setting,
including heat and AC off. I disconnected the green wire from the
thermostat and it kept running. From everything I read that
indicated
a stuck fan relay. When I looked at the fan really it was cooked,
burned plastic, etc. So I replaced it with the same model. I'm
pretty sure I wired it exactly the same, I took notes, etc. So now
I
got the weird situation described above. I picked up a new
thermostat
thinking that maybe the burned relay took out the thermostat but it
does the same thing. That makes me believe I did screw up the
wiring
but after much reading and checking and rechecking the wiring looks
right. Does any know what could cause this?


thanks


You're right. You messed up on the wiring. Check the units blower
door
for
the mfg.'s wiring diagram, and compare notes. I think you'll find
you've
mis-wired the relay. And BTW, if you're not careful, you will let ALL
THE
FACTORY SMOKE out of the motor and it won't run at all.


--
Zyp


I'm pretty sure something is not wired right, despite my best effort.
There is no wiring diagram in the blower units door unfortunately.
Assuming I have the thermostat connected correctly...


What I've got is..
power coming in (white and black and bare "ground")
red and black on the N/O side of the fan relay, a black and a white on
the coil of the relay
a blue and a white going to the oil burner motor
a red, an orange, and a black going to the fan limit control


any ideas?


The colors mean little. You need a diagram. Your fan/limit control may be
defective


If I had a diagram I'd be all set
There in lies the problem. There's no diagram to be found.
I'm thinking that the fan limit control may be bad as well, but until
I get it wired correctly I won't know.


If you can identify the make and model, the manufacturer may have a diagram
on their website


I figured it out.
It was a wiring mistake on my end. I just started from scratch. My
mistake was trying to figure out the problem with the way it was
currently wired. I just disconnected everything and work the wiring
out logically.
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