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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a lennox conservator 3 g16. I had to replace the

Customer Question

I have a lennox conservator 3 g16. I had to replace the flame sensor. Did so. Well when I was taking it out I unplugged it from the Robertshaw 780-745 (ignition control?). When I did so I also accidently unplugged 2 other wires. And now, I tried plugging it back in but now my pilot won't light. Ignitor is clicking just no gas. I know that the mv quick connect is red, GND is green, and tr next to that is yellow. But I have th, pv/mv, and pv and the color wires I don't know which go to them. I have brown (kind of?), blue, and orange.
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: 20 min
JA: Do you plan on doing the work yourself?
Customer: Yes
JA: Anything else we should know to help you best?
Customer: Not that I can think of
Submitted: 5 months ago.
Category: HVAC
Expert:  D.E. Anderson replied 5 months ago.

Hi, how are you? Can you tell me which component each of those wires are running to? I have pulled a diagram up but that's a replacement module and I want to make sure that the wires are the same and haven't been altered through servicing. Thanks

Customer: replied 5 months ago.
Red, blue, and orange are coming from the gas valve.
Customer: replied 5 months ago.
Sorry...also brown I have no idea where it goes, yellow goes to what I think is the thermostat control on the furnace side, green obviously ground.
Customer: replied 5 months ago.
I beleive I have them connected correctly now though. I finally got the pilot lit...but the ignitor keeps clicking and won't let the burner come on. I'm assuming it has something to do with the flame sensor.
Expert:  D.E. Anderson replied 5 months ago.

Ok, Red, you said you are certain is MV, Blue should be on PV on the valve and PV on the controller. Is there a mv/pv terminal on your gas valve?

Customer: replied 5 months ago.
I beleive so, but it's not labeled on the gas valve
Expert:  D.E. Anderson replied 5 months ago.

Trace the brown wire back and tell me where it goes to

Expert:  D.E. Anderson replied 5 months ago.

The gas valve doesn't have any labels? Can you get a model number off of the valve for me?

Customer: replied 5 months ago.
Here is the brown wire and the info for the gas valve.
Expert:  D.E. Anderson replied 5 months ago.

Wire the brown to TH

Expert:  D.E. Anderson replied 5 months ago.

Can you take a picture of the wire terminations on the gas valve for me?

Expert:  D.E. Anderson replied 5 months ago.

PV from the controller should wire to PV on the valve and MV to MV and then you should have a common connection.

Customer: replied 5 months ago.
I think every thing is plugged in appropriately now. But I'm not sure about the orange and white. Orange goes to the gas valve and the white is my flame sensor.
Expert:  D.E. Anderson replied 5 months ago.

You have to have a common wired to the gas valve. So I think your orange is your common. There should be a terminal on the controller labeled flame sense.

Expert:  D.E. Anderson replied 5 months ago.

wire orange to the MV/PV terminal on the module

Expert:  D.E. Anderson replied 5 months ago.

Try to run it.

Customer: replied 5 months ago.
Now the blue wire is not connected to anything (that comes from the gas valve) and now the pilot is not kicking on. I'm going to turn the valve off for a few minutes then turn it on and try again.
Customer: replied 5 months ago.
For the 3 plugs at the bottom where the orange and white wires were say pv for the top sensor for the middle and remote for the bottom.
Customer: replied 5 months ago.
the pilot still didn't light by the way.
Expert:  D.E. Anderson replied 5 months ago.
I thought you wired blue from PV on the gas valve to PV on the module.
Customer: replied 5 months ago.
If I keep the blue in pv/mv and plug the white line (flame sensor) in the middle at the bottom and orange into the one above it (pv) then the pilot kicks on but the ignitor continues to click and the burner will not kick on
Expert:  D.E. Anderson replied 5 months ago.

I need to opt out as I have an unexpected situation arising at home. I apologize for the inconvenience. There should be another expert shortly to assist. Thank you for your understanding.

Expert:  BillyHvac replied 5 months ago.

does this look like your wiring?

It is how the unit was wired new...click here

Customer: replied 5 months ago.
If I'm seeing this correct not quite. The gas valve has an orange wire going to the control. That's the wire I'm not 100% is in the correct spot. But like I told the last guy everythi g is coming on appropriately except the ignitor continues to try to click and light the pilot that it has already lit.
Customer: replied 5 months ago.
It seems to me that the new flame sensor that I got is not working like it should to tell the system to stop the ignitor and turn the burner on.
Expert:  BillyHvac replied 5 months ago.

.

Customer: replied 5 months ago.
with this picture, I just discovered this little green wire not connected to anything. It's comes from my thermostat. Should I connect it to the green wire next to the empty space or possibly the empty screw?
Expert:  BillyHvac replied 5 months ago.

There are 2 greens that I see...the one hanging loose....what does other end go to?

I see a green on G which should come from stat

Expert:  BillyHvac replied 5 months ago.

does this look closer? click here

Expert:  BillyHvac replied 5 months ago.

and here is about spark after pilot lit...click here

Customer: replied 5 months ago.
It would help but it doesn't make too much sense to me plus I am not able to check continuity. Everything seems to be fine and work properly otherwise.
Expert:  BillyHvac replied 5 months ago.

ok, terminal 6....what wire is attached and where does it go?

Expert:  BillyHvac replied 5 months ago.

And if you can bear with me...

On terminal R where thermostat wires attach...there are 2 reds. One goes to thermostat..where does the other go?

Customer: replied 5 months ago.
I do not think I understand. I have to leave for a moment and go pick up my kids.
Customer: replied 5 months ago.
Is it possible that the new flame sensor is bad?