Gas Valve Wiring

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  #1  
Old 11-23-07, 03:56 PM
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Gas Valve Wiring

As the cold temps have arrivied in Texas, I found that our HVAC was not delivering heat. Trane unit, about 10 years old, natural gas with electronic ignition (no pilot). The ignition element comes on, but no gas flows and it eventually shuts down. I have the blower set to run at all times, and have verified that the thermostat and safety devices/interlocks are all operational and not a problem.

In the process of inspection, I found that the gas valve relay clicks on when the power to the system is first energized. There is a 5 wire connector connecting to the White-Rodgers, 36E35-201 gas valve. I can position the wires from this connector slightly and cause the relay(s) to click... and now find that this might be the cause of my problem.

The gas will properly flow to the igniter... when holding the harness stable in one position... and things run correctly with eventual turn off (adequate heat or other factor)

If I hold the harness stable in a different position... the original failure occurs (no gas flows).

Reseating the connector does not seem to improve things.

Can the black module be removed for inspection? What care is needed?
 
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Old 11-23-07, 04:21 PM
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Originally Posted by cdave151 View Post

The gas will properly flow to the igniter... when holding the harness stable in one position...
Reseating the connector does not seem to improve things.
So it does sound though like you are changing something. What exactly are you moving?, and what are you keeping stationary? And have you ran furnace tests by doing this and not doing this, to rule out coincidence?

Can the black module be removed for inspection? What care is needed?
Are you talking about something resembling a 1 to 1 1/2 inch rectangular cubish thing, or are you talking about something much larger like a main control box that might be 3 inches wide by 6 inches long?
 
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Old 11-23-07, 09:22 PM
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Hi cdave:

Use the search feature here and look for a poster called poochiestyle. I think you have the same system he/she has. Can you post the model # from the ignition module?
 
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Old 11-25-07, 07:13 AM
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Originally Posted by ecman51` View Post
So it does sound though like you are changing something. What exactly are you moving?, and what are you keeping stationary? And have you ran furnace tests by doing this and not doing this, to rule out coincidence?

Are you talking about something resembling a 1 to 1 1/2 inch rectangular cubish thing, or are you talking about something much larger like a main control box that might be 3 inches wide by 6 inches long?
I grasped the 4 wire wire bundle, close to the connection point on the gas valve. As I shift the wire bundle slightly from one side to another, I hear the relay click on and off.

When I observe that the igniter (over by the actual gas jets) is not lighting the gas (up to a second past igniter safety shutdown), I can gently push the wire bundle (attached to the gas valve) to one side and the relay clicks, gas flows, and the furnace gas ignites and operates correctly.

Sometimes the gas stops flowing prematurely, and I can resurrect it instantly by touching the wire bundle again.

Today I tied the cable bundle at the gas valve with a long cable tie to hold it in one direction... and this results in a more stable (altho not perfect) operational condition.

I am not referring to my control box... (sigh) outdated WR 50A52-102 control (radiant flame sense). The furnace is a Trane TUE100A900H.

My question remains, to repair (rather than gas valve replace) should I remove the subassembly that the 4-wire bundle connects to? It is black, about 1"x2.5" with a single connector body that the wires plug into. It seems to house a small transformer.

My intention is to closely examine the subassembly for sources of intermittent connection and repair if possible. Perhaps it is as simple as bending one of the cable connector pins to assure constant contact?
 
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Old 11-25-07, 07:20 AM
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Originally Posted by daddyjohn View Post
Hi cdave:

Use the search feature here and look for a poster called poochiestyle. I think you have the same system he/she has. Can you post the model # from the ignition module?
Trane furnace TUE100A960H
Control assy = White Rodgers (Emerson Electric) 50A52-102
written on front "D340783P01 replace with CNT1845"

It seems to be one of those radiant flame sense models, as I do not see any signs of a conversion kit.
 
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Old 11-25-07, 11:52 AM
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Hi dave:

I assume you read the other thread? You can try looking inside the subassembly on the gas valve; you might get lucky. Sooner or later you'll need to either do the conversion or replace the furnace.
 
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Old 11-25-07, 11:56 AM
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Is this a smart valve? It woud be, I'd imagine, if there were any led function light on the valve, and a board internally coupled to the valve. I had to replace one on gas water heater acting same way as yours. Had molex plug that could make heater run if I jiggled the plug. I removed plug and observed all round pins and none were spread or corroded. Reinserting did not seem to help as much as pushing on the whole plug assembly. Finally had to give up and buy the expensive smart valve. But indeed fixed the problem, to everyone's satisfaction: tenent, me, and boss that the expensive part was indeed it.
 
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Old 11-25-07, 07:44 PM
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Originally Posted by daddyjohn View Post
Hi dave:

I assume you read the other thread? You can try looking inside the subassembly on the gas valve; you might get lucky. Sooner or later you'll need to either do the conversion or replace the furnace.
... lucky :mask:

The gas valve subassembly easily removed via 2 screws, and found the culprit to be one of the connector pins that is soldered to a PC board was loose. A touch of solder at the pin's connection on the PC board was all that was needed.

After re-assembly, the gas ignites each and every time. Wiggling the wires leading to the gas valve's connector no longer results in intermittent clicking of the relay.

Thanks for the encouragement!

(sigh) I'll get a Control/Sensor conversion kit, and hold it as a spare until actually needed.
 
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Old 03-01-11, 05:47 PM
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Intermittent Ignitor operation

I have the exact gas valve and furnace, but now add 4 + years as mine is now 15 years old. At times I can wiggle the wiring around and the same thing occurs, but other times not, so I think I have more than one problem. I ohmed all the switches out with no problems noted. The ignitor will cycle on and off sometimes and the burners will never light up or they will light up and it could run for a few minutes to a few days before it shuts down before we have to reset the system (unplug the unit and plug it back). I bought the upgrade kit09660 that allows you to convert from the radiant sensor to the flame sensor. And yes they are not cheap. $300 to $400 is the range, but being mine is this old now I was afraid they would stop making the kit. I might end up regretting it before it is all said and done, but oh well, live and learn, right? I will remove the top half of the valve at the same time I will upgrade the control unit and accessories. I do not think our valves are a "smart valve" it looks standard (no LEDs), even though I had been looking for one, I could not find one. I will keep everyone posted. Thanks!
 
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Old 11-09-11, 08:41 PM
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The kit fixed all the problems, but unfortunately I had a miserable hot summer and recently replaced the furnace and condensing unit by going to a 5 ton unit up from a 4 ton. I hope it is not too large. We will see this summer.
 
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