Hi All,

I have a Lennox furnace (G26) with a problem now: the blower fan cannot be auto on or off, I should always put it to ON from the controller. If I put it to Auto, it wouldn't work.

Please help me figure out the problem.

Thanks,

Patrick

On Monday, March 9, 2015 at 1:53:10 PM UTC-4, wrote:
Hi All,

I have a Lennox furnace (G26) with a problem now: the blower fan cannot be auto on or off, I should always put it to ON from the controller. If I put it to Auto, it wouldn't work.

Please help me figure out the problem.

Thanks,

Patrick

What happens when it's on auto? Furnace fires up, overheats, then shuts down?
What age is this furnace? If it's an old furnace, they used a thermostatic
switch that turns on the blower when the plenum gets warm enough. Newer furnaces for probably last two decades typically have the on/off function
designed into the main control board. If you have the former type, then
it's probably the thermostatic switch. If you have the latter, it's a bit
strange, because the controller board also has to turn it on in response to
the thermostat fan switch calling for it to be turned on when you do it
manually. So, it would seem more likely that the fan just wouldn't go on
at all, but it's possible a fault on the controller board could cause it.

Thanks.

When turning it on Auto, the furnace can fire up, but the blower fan will never on. This causes furnace to be overheats then shuts down.

The furnace is about 8 years old.. where is the thermostatic switch located most likely?

Thanks,

Patrick

On Monday, March 9, 2015 at 2:53:17 PM UTC-4, Patrick Feng wrote:
Thanks.

When turning it on Auto, the furnace can fire up, but the blower fan will never on. This causes furnace to be overheats then shuts down.

The furnace is about 8 years old.. where is the thermostatic switch located most likely?

Thanks,

Patrick

With the model number you should be able to find a wiring diagram online.
Or there typically is one on the inside of one of the removable panels
that give you access to the two furnace compartments. That would show
how it's wired, if it even has a switch. If it's only 8
years old, it may not have a thermostat switch for the blower. Newer
ones are just timed to go on X secs after the furnace fires up. If
it has a switch, it's located somewhere near the top where it can measure
the plenum temperature.

wrote in message
...
Hi All,

I have a Lennox furnace (G26) with a problem now: the blower fan cannot be
auto on or off, I should always put it to ON from the controller. If I put
it to Auto, it wouldn't work.

Please help me figure out the problem.

Thanks,

Patrick


You shoulda bought a Goodman, chump.
LOL

wrote:
Hi All,

I have a Lennox furnace (G26) with a problem now: the blower fan cannot be auto on or off, I should always put it to ON from the controller. If I put it to Auto, it wouldn't work.

Please help me figure out the problem.

Thanks,

Patrick

Hi,
Your G26 is high efficiency furnace with at least 92% efficiency. When
it fails(going down with over heat) you should read trouble code.
Two LED indicators blinking. There must be inside the furnace cover
panel, you should have a trouble code chart or in your owner's manual.
When you say you keep the fan running from furnace side. Are you
jumpering G and R terminal on the control board thermostat interface
terminal strip? If so Did you try same from your thermostat side?
Trouble-shooting requires logical steps. 3 things to check is in order
is thermostat wiring from thermostat to furnace control board.
Good luck. Also check you warranty some comes with 10 year warranty.
Our furnace came with 10 year P&L warranty.
黃公

On Monday, March 9, 2015 at 4:19:00 PM UTC-4, Tony Hwang wrote:
wrote:
Hi All,

I have a Lennox furnace (G26) with a problem now: the blower fan cannot be auto on or off, I should always put it to ON from the controller. If I put it to Auto, it wouldn't work.

Please help me figure out the problem.

Thanks,

Patrick

Hi,
Your G26 is high efficiency furnace with at least 92% efficiency. When
it fails(going down with over heat) you should read trouble code.
Two LED indicators blinking. There must be inside the furnace cover
panel, you should have a trouble code chart or in your owner's manual.
When you say you keep the fan running from furnace side. Are you
jumpering G and R terminal on the control board thermostat interface
terminal strip? If so Did you try same from your thermostat side?
Trouble-shooting requires logical steps. 3 things to check is in order
is thermostat wiring from thermostat to furnace

How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming on,
furnace safety then shutting the furnace down? And similarly, how would
a fault in either of those explain the fact that the fan works with
the manual fan selection at the thermostat? Every furnace I've seen,
if that problem description is accurate, the problem has to be at
the furnace.

On 3/9/2015 6:57 PM, trader_4 wrote:


How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming on,
furnace safety then shutting the furnace down?

95% of the heating and AC posts here start with "I replaced the
thermostat and the heater still does not work" Its a tradition.

trader_4 wrote:
On Monday, March 9, 2015 at 4:19:00 PM UTC-4, Tony Hwang wrote:
wrote:
Hi All,

I have a Lennox furnace (G26) with a problem now: the blower fan cannot be auto on or off, I should always put it to ON from the controller. If I put it to Auto, it wouldn't work.

Please help me figure out the problem.

Thanks,

Patrick

Hi,
Your G26 is high efficiency furnace with at least 92% efficiency. When
it fails(going down with over heat) you should read trouble code.
Two LED indicators blinking. There must be inside the furnace cover
panel, you should have a trouble code chart or in your owner's manual.
When you say you keep the fan running from furnace side. Are you
jumpering G and R terminal on the control board thermostat interface
terminal strip? If so Did you try same from your thermostat side?
Trouble-shooting requires logical steps. 3 things to check in order
is thermostat wiring from thermostat to furnace control board.

How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming on,
furnace safety then shutting the furnace down? And similarly, how would
a fault in either of those explain the fact that the fan works with
the manual fan selection at the thermostat? Every furnace I've seen,
if that problem description is accurate, the problem has to be at
the furnace.

trader_4 wrote:
On Monday, March 9, 2015 at 4:19:00 PM UTC-4, Tony Hwang wrote:
wrote:
Hi All,

I have a Lennox furnace (G26) with a problem now: the blower fan cannot be auto on or off, I should always put it to ON from the controller. If I put it to Auto, it wouldn't work.

Please help me figure out the problem.

Thanks,

Patrick

Hi,
Your G26 is high efficiency furnace with at least 92% efficiency. When
it fails(going down with over heat) you should read trouble code.
Two LED indicators blinking. There must be inside the furnace cover
panel, you should have a trouble code chart or in your owner's manual.
When you say you keep the fan running from furnace side. Are you
jumpering G and R terminal on the control board thermostat interface
terminal strip? If so Did you try same from your thermostat side?
Trouble-shooting requires logical steps. 3 things to check is in order
is thermostat wiring from thermostat to furnace control board.

How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming on,
furnace safety then shutting the furnace down? And similarly, how would
a fault in either of those explain the fact that the fan works with
the manual fan selection at the thermostat? Every furnace I've seen,
if that problem description is accurate, the problem has to be at
the furnace.

Ed Pawlowski wrote:
On 3/9/2015 6:57 PM, trader_4 wrote:


How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming on,
furnace safety then shutting the furnace down?

95% of the heating and AC posts here start with "I replaced the
thermostat and the heater still does not work" Its a tradition.

Hmm,
I suggested to check three parts including control board. I did not
define the problem. I wish I had a magic to point my finger right off
the bat to the problem.

Tony Hwang wrote:
Ed Pawlowski wrote:
On 3/9/2015 6:57 PM, trader_4 wrote:


How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming
on,
furnace safety then shutting the furnace down?

95% of the heating and AC posts here start with "I replaced the
thermostat and the heater still does not work" Its a tradition.

Hmm,
I suggested to check three parts including control board. I did not
define the problem. I wish I had a magic to point my finger right off
the bat to the problem. OP, I'd appreciate the feedback after problem is
solved.

Tony Hwang wrote:
Tony Hwang wrote:
Ed Pawlowski wrote:
On 3/9/2015 6:57 PM, trader_4 wrote:


How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming
on,
furnace safety then shutting the furnace down?

95% of the heating and AC posts here start with "I replaced the
thermostat and the heater still does not work" Its a tradition.

Hmm,
I suggested to check three parts including control board. I did not
define the problem. I wish I had a magic to point my finger right off
the bat to the problem. OP, we'd appreciate the feedback after problem is
solved.

Tony Hwang wrote:
Tony Hwang wrote:
Tony Hwang wrote:
Ed Pawlowski wrote:
On 3/9/2015 6:57 PM, trader_4 wrote:


How would a fault in either the thermostat or the wiring to the
thermostat result in the furnace starting, firing, the fan not coming
on,
furnace safety then shutting the furnace down?

95% of the heating and AC posts here start with "I replaced the
thermostat and the heater still does not work" Its a tradition.

Hmm,
I suggested to check three parts including control board. I did not
define the problem. I wish I had a magic to point my finger right off
the bat to the problem. OP, we'd appreciate the feedback after
problem is solved. If your trouble-shooting reached control board, time
to check fan switch B4 replacing the board.

On 3/9/2015 2:53 PM, Patrick Feng wrote:
Thanks.

When turning it on Auto, the furnace can fire up,
but the blower fan will never on. This causes furnace
to be overheats then shuts down.

The furnace is about 8 years old.. where is the
thermostatic switch located most likely?

Thanks,

Patrick


Under the cover, front wall, near the burners.

-
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

Goodman furnaces rule!

Stormin Mormon wrote:
On 3/9/2015 2:53 PM, Patrick Feng wrote:
Thanks.

When turning it on Auto, the furnace can fire up,
but the blower fan will never on. This causes furnace
to be overheats then shuts down.

The furnace is about 8 years old.. where is the
thermostatic switch located most likely?

Thanks,

Patrick


Under the cover, front wall, near the burners.

-
.
Christopher A. Young
learn more about Jesus
. www.lds.org
.
.
Hmm,
Lennox G26 series may or may not have primary limit switch(Lennox call
it) depending on model. They use several different control board.