[tutooo]

Hi everyone. I am new and this is my first post.

I am trying to figure out why one of my cooling systems is not working properly and was hoping I can get some advise. I have a Lennox G40UH(X) heating/cooling system and I noticed that it does not cool when I tested out the AC this week. I moved into my home a few months ago and this is the first time I tried to turn it on. I tried my best to troubleshoot and confirmed that the fan on the outside unit is working and air is blowing through the vents inside from the furnace as well. I then went upstairs to take a closer look at the furnace and notice that the burners turn on every time even though I set the thermostat to 'Cool'. Is this normal? The previous owners made some repair to the unit before I moved in and I am scared that the technician wired something wrong.


Thanks.
tutooo

 

[roughneck]

Sounds wired wrong. Or possibly has the wrong thermostat.
The furnace should not turn on with the cooling.

 

[tutooo]

That was my logic and thank you for confirming. The thermostat is the original unit installed (Honeywell) and I tried replacing it with the same unit I have downstairs.

I also noticed inside the furnace a green wire that was not connected to the 'G' connection so i connected it but the results are the same.

 

[roughneck]

G is for the blower. Or someone was stealing a common using that wire.

 

[tutooo]

I have no idea what is going on right now. I am a handy guy but have zero experience with cooling/heating systems. I opened the covers off of my second furnace to try and compare the wirering to the circuit board and notice that the good furnace only has 6 wires wile the one i am having trouble with has 8 going to it. They both have humidifiers hooked to them. I tried attaching a picture of the one I am having issues with.

 

[roughneck]

The white wire on Y is the issue. But why is there 3 white wires?

 

[tutooo]

I wish I knew. Here is a picture from the working unit. It also has a second wire going to 'Y' but it is red and it has a white one going to 'C'. Not sure why this one has less wires connected to it.

 

[roughneck]

You'll have to trace the wires out. Should be one multi conductor running the outdoor unit, and another running to the thermostat. Have to see there the third goes, maybe to a condensate overflow switch or some other accessory

 

[user_12345a]

The second wire could be for an accessory like a humidifier - not the best way to wire it but it works.

There's most likely a short between W and Y - wires touching.
could also be a heatpump wired to the furnace to defrost.

When you turn on the heat, does the a/c come on?

You can disconnect and tape off the wires to W temporarily if u wish to use the a/c. Having the furnace fire at the same time supplying 110F+ air to the indoor coil will damage the a/c.

 

[tutooo]

You'll have to trace the wires out. Should be one multi conductor running the outdoor unit, and another running to the thermostat. Have to see there the third goes, maybe to a condensate overflow switch or some other accessory

Here is how it is connected at the thermostat:

First pic with the blue wire on 'Y' is the system I am having trouble with. There is no yellow wire. The second is the working one.

 

[roughneck]

The thermostat is wired correctly

 

[BayouRunner]

There are two white wires on the W. Disconnect the one on the right in the picture and I think it will work. Otherwise you have something wrong at the thermostat. My reasoning behind this is The white wire on the left is in the same bundle as the red r wire so I am assuming this is going to the thermostat. It won't hurt anything to try it.

 

[tutooo]

The second wire could be for an accessory like a humidifier - not the best way to wire it but it works.

There's most likely a short between W and Y - wires touching.
could also be a heatpump wired to the furnace to defrost.

When you turn on the heat, does the a/c come on?

You can disconnect and tape off the wires to W temporarily if u wish to use the a/c. Having the furnace fire at the same time supplying 110F+ air to the indoor coil will damage the a/c.

Hi. I don't think there is a direct short between W and Y. I tried removing and tightening them.

I don't believe it does. I used the heating this winter and it seemed to work fine. I hope I did not have the AC blasting the entire time

 

[BayouRunner]

I saw the picture of the thermostat after I posted. Nothing wrong there

 

[tutooo]

There are two white wires on the W. Disconnect the one on the right in the picture and I think it will work. Otherwise you have something wrong at the thermostat. My reasoning behind this is The white wire on the left is in the same bundle as the red r wire so I am assuming this is going to the thermostat. It won't hurt anything to try it.

Thanks. I will try this later tonight when I get home from work.

So what input is for the heater? 'W'?

 

[roughneck]

W is heat
Y is cooling
R is 24 V
C is common
G is fan

 

[user_12345a]

The short could be in the wire.

Follow the second wire on w, see where it goes - try disconnecting it.

 

[tutooo]

Thanks for confirming the Thermostat is wired id roughneck and BayouRunner.

I am sure the problem is the setup at the furnace. I found a box with a control board in it. Looks like someone replaced it before I moved in to fix the heating and wired it wrong.

 

[tutooo]

W is heat
Y is cooling
R is 24 V
C is common
G is fan

Thanks. Did I do anything wrong by connecting the green wire to 'G'? Is was disconnected when I first looked at it.

 

[BayouRunner]

The w actually is the wire that is calling for heat. There should only be one wire hooked to w and it should go directly to the thermostat. I have no idea of where that other white wire is going to but there should only be one. Another theory could be the programming on the thermostat if that one is programmable. It could be set up for a heat pump but lets try removing that wire first, then post up what happens and we will go from there. I would like to know what that other wire goes too if removing the white wire does not work.