Nordyne Gibson KG6RC-100C-16B Problems

[vson]

Nordyne Gibson KG6RC-100C-16B

I have just installed a pressure switch that I just ordered from you, and now realize that this is not the problem. I have checked all of the safety switches and all seem to be getting 24-26VAC to both sides of them. Now here is where I am stumped; there are two wires to the GV - yellow (the 24V supply wire), and black (the return wire). When I only unhook the black I can read 15Vac across the GV, and I can read 24-26Vac when it switches for it to come on. When I attach the black back to the GV, I get .4Vac accross the GV, and sometimes nothing when it switches on. The problem is, sometimes it lights and goes for about 10 seconds, and sometimes it just clicks and resets. I am stumped as to whether I need a new GV, or a new control board.

Can anyone shed any light on this, or give me some other chices to check? Any help would be appreciated,

Thanks

[Robert]

Hi,

Does the control board have a flashing diagnostic light ? If so, is it flashing and if so, how many times ?

Disconnect yellow and black wires, set t-stat to call for heat, wait about a minute and see what you read across the two wire disconnected.


Thanks,
Robert

[vson]

The light blinks twice sometimes, and sometimes it blinks three times - both pressure related. When I disconnect the two wires and check the yellow to chassis, I get 15Vac initially, and 24-26Vac when it is tripped on, the black reads 0Vac from the black to chassis.

[Robert]

See if the small booster fan motor comes on with a call for heat immediately.

If so, does it sound to be running good and smooth ?


Is the air pipe from booster motor connected tight and clear with no blockages ?


Are the small tubes or tube connected to pressure switch tight, unkinked, clear and not damaged ?


If so and all above seems/appears ok, then probably a bad pressure switch without being there to test it.


Let me know if you need ordering info.


Thanks,
Robert

[vson]

I checked all tubes, and the induction motor comes on just fine - I just replaced the capacitor for that, it went out. What doesn't make sense to me, is that when I hook up the yellow wire to the GV and leave the black wire off, I can read 24Vac across the Gv contacts, but when I hook the black wire back up to the Gv, I can't read anything at the Molex connector. It acts like a dead short, but I don't know much about the board circuitry. The real funny thing is, sometimes it actually lights when I am reading no voltage across the Molex connector (black to chassis). Is this the way this is suppose to work? My thought is I should always read 24Vac from black to chassis when the Gv is acuated.

If you think the Gv is bad, do you have a p/n? Thanks

[Robert]

Did you set t-stat to call for heat, wait 45 secs. to a minute then test across the black and yellow gas valve wires with them disconnected ?


Not talking about testing each to ground, but testing across them with a meter lead on each at same time with a call for heat.



Thanks,
Robert

[vson]

What am I suppose to read when I test across them when it calls for heat? Should I read 24Vac across them when it calls for heat? If it does read 24Vac across them when it calls for heat, is it more likely that the GV is bad versus the board?

I also noticed that it will not hold the 24Vac when it calls for heat when the wires are disconnected, is this a safety thing? It will hold 24Vac for about 10seconds and then reset.

Thanks in advance

[Robert]

Hi,

Yes, should read 24vac.


Yes, if you have 24vac is is more likely to be bad GV.


Could be a safety, haven't looked at parts or furnace info to see if there is a safety in circuit for that.


Probably a remote flame sensor or the ignitor acting as flame sensor kicking power off to GV when no flame is sensed.



Thanks,
Robert

[vson]

Checked the voltage across those two wires at lunchtime, I let it call for heat three times and I always recieved a 24Vac reading across the yellow and black wires. I have ordered a new Gv and I will see if this fixes the problem-fingers crossed.

I will try to let you know the result after getting the new valve,

Thanks for the help,

[Robert]

Hi,

You're very welcome, happy to help.

I'd say with what I know without being there that the GV would be a prime suspect.


The 24vac low voltage circuit goes through all the safeties, board and all enroute to GV.


So, it sounds like a short in GV/GV solonoid.


Thanks,
Robert

[vson]

Well I got the new valve today, and just put it in, only to find the same problem- gas valve clicks, I get ignition, and as soon as the blower came on, it went out. Second time it tried, the gv just clicked and then I got three blinking lights. Third time, same thing, Gv clicked and then I got three blinking lights.

Any ideas what to replace now? I am not sure where to check next, and I have no local technicians, so I would like to make the next steps.

Thanks in advance.

[Robert]

Have you inspected the ignitor and flame sensor that I originally

suspected ? Without being there to do tests, allIi have to go by is

what is given.


IF it IS igniting, then going out when blower starts, look closely at

ignitor and flame sensor.


What does your diagnostic codes say for 3 flashes ?



Thanks,
Robert

[vson]

The ignitor glows very bright and occasionally it does ignite. The flame sensor I took snadpaper to, and made sure it was clean. The three flashes say that the pressure switch is stuck open.

Are there some readings I should take off the ignitor and sensor? Are there additional radings I should check on the board? Would a bad relay be causing this?

Thanks

[Robert]

Clean the flame sensor with steel wool, not sandpaper. Do not touch it or ignitor with bare hands.

IF ignitor is getting 120vac for about 30 seconds about 1 minute into a heat cycle, it should be glowing.


When it glows, you get ignition at burner IF gas valve is working and there is correct gas pressure.


Not really nothing else that you can DIY for it.


With the control board flashing a code, but system still working at times, could be the board, the ignitor, flame sensor, gas valve. etc.


Just too many variables to diagnose withoutthorough testing of entire cycle and circuits.


Thanks,
Robert