Buzzing noise / Gas Valve area

ag162

Hello,
Older Comfortmaker RPJ Furnace with AC:
Let me start with the beginning of the problem, this summer.
Cutting grass with a wead eater by my AC core,,,caught the thermostat or switch wires,,,they wrapped around the stem and broke...the core stopped running and I went into the house to turn off the ac/furnace. I spliced the wires back and turned the furnace back on,,,then the heat and ac ran, while making a buzzing noise from the gas valve unit in the furnace..the noise if coming from a cylintrical plastic cover that has a metal clip holding it on. So, being in the summer, I simply turned the pilot gas off and unplugged the thermocouple to shut it up. Now, with winter getting closer, it is time to fix this. So, #1. the piece making noise is right behind the pilot gas knob, #2 What is it? #3, when plugged up, the furnace will come on, then the buzzing starts and stops intermittantly, but the furnace flame will not go out, and the blower stays on also.
Is this a valve that if controlled with an electro magnet and is failing to shut off and the noise is being created by being stuck? Any help is appreciated.

hvaclover

Your splice is either causing a voltage drop or you ruined the the gas valve or transformer.

Model # and age would really be a lot of help to walk you thru the repair

__________________
Just slow, not stupid.

ag162

OK,
Comfortmaker RPJ Furnace
Model # GDE090A12ATN
Year 2-90

I went out and checked my connections, they were twisted and taped tightly with no corosion. Either way, I cut them, and soldered them with heat shrink tubing. Ready for the test,,,plugged the ignitor in, turned the gas on and turned the power on....put the thermostat up one degree from room temp,,,the heat came on,,,worked fine...when the temp reached the cut off point,,,the buzzing started and the furnace again, would not shut off....
This seems to tell me that the shut off is not working. What do I chack now?

Thanks in Advance,
A.Gore

hvaclover

That model is not accurate. There is no ***090**** listed.
Is this an 80 or 90% furnace?

Still could be a voltage drop and the gas valve could still be bad..but try isolating the 24 volt contactor inside the ac (take the the two wires you spliced of the contactor and see if the furnace runs then).

Recheck the model and re-post please. Thinking very strongly about the valve.

You have a volt meter?

__________________
Just slow, not stupid.

ag162

http://www.fileden.com/files/2007/4/...6/SANY1706.JPG
http://www.fileden.com/files/2007/4/...6/SANY1707.JPG
http://www.fileden.com/files/2007/4/...6/SANY1710.JPG

Here are pics of the gas valve, circuit board and full name. On the pic of the gas valve, has a blue pilot knob, right behind it is a black plastic cylinder with a silver metal strap, this is what makes the buzzing sound.

Thanks,
A.Gore

kenmac

That is a solenoid that pulls / holds plunger up for gas flow

hvaclover

Yes you have an old 20 year old furnace.

The part indicated is the gas valve. I need to know if the furnace tries to relight the burners.

First I want you to push the thermostat up to max, Then turn the power off to the furnace. Should be a light switch on the side of the furnace. Turn it off for a count of sixty...turn it back on. It should glow red inside the burner section within about two minutes. The burners should light.

Do that and tell me what happens.

__________________
Just slow, not stupid.

hvaclover

You mentioned Cyprus..are you GreeK?

__________________
Just slow, not stupid.

ag162

Ya, all worked as normal. it is on. now what is the next test?

ag162

Well, I have to call it quits for tonight. When I turned the thermostat down, the valve started buzzing again. If this is based on an electrical charge to actuate a valve, then the voltage or amperage may be low. I will check this with the meter tomorrow.

Thanks for all your help,
A.Gore