Jandy JXi 400N Not Igniting - Help

JamesW

TFP Expert
Mar 2, 2011
25,004
Seems like the power supply is dropping out or the valve is shorting out.

I really don't know what else to check.
 

swamprat69

Well-known member
Mar 30, 2019
460
Las Vegas, NV
It would be helpful if you answered/confirmed any questions that were asked. From what I understand, you never get any flame/heat during the ignition sequence and never smell any raw gas odor from the vent discharge...correct? Does the Fenwal ignition module show any fault codes?
 

b2cperson

Member
May 7, 2021
12
North Carolina
It would be helpful if you answered/confirmed any questions that were asked. From what I understand, you never get any flame/heat during the ignition sequence and never smell any raw gas odor from the vent discharge...correct? Does the Fenwal ignition module show any fault codes?
  • Heater Blower turns on and remains on
  • Igniter glows
  • Hear a clicking sound, ignitor stops glowing
  • No natural gas discharge or smell, even when opening the 3/4" coupler between the gas valve and the blower gas orifice
  • Heater never ignites
  • Approx 30 seconds later Ignitor begins glowing again, same as above
  • Tries 3rd time, then shuts down completely with error message to "check ign steps"
  • LED Light on Ignition Control remains off and does not blink
Parts Replaced So Far:
  • New Gas Valve
  • New Water Pressure Switch (replaced due to a visible crack)
  • New Fenwal Ignition Control
Gas Valve:
  • After the ignitor glows and I hear a click, I get 26.0 v AC between the Yellow and Brown wires, when disconnected from the Gas Valve (see photo "Valve During Startup 3"). Voltage remains constant for about 5 seconds then drops to zero volts and the cycle restarts
  • Checking voltage at the valve with the Yellow and Brown wires attached shows 0.00 v AC. Meaning, I leave the wires attached and test for voltage at the valve electrical connections and get 0.00 V AC. (See Photo "Valve Voltage Test" I would expect to see the same 26.0 v as in the step above.
Gas Pressure:
  • Measure gas pressure at the 1/8" plug located on the inlet side of the gas valve. I measure pre-startup and after the voltage call to the gas valve. The pressure remained at 7.6 in WC

Resistance Testing:
  • Ignitor: Removed the wires from the ignitor and tested resistance between the leads coming out of the ignitor got 58.6 Ohms( See Photo "Resistance at Ignitor")
  • Gas Valve: I checked resistance three ways as recommended by commenters with valve in the "On" position
    • Resistance at Solenoid Wires: 19.5 Ohms (See Photo "resistance at solenoid wires")
    • Resistance at Solenoid Terminals: 106.9 Ohms (See Photo "resistance at solenoid terminals")
    • Resistance at gas valve terminals where Yellow and Brown Wire Connect, with the Yellow and Brown cables removed: 16.5 Ohms
    • NOTE: I get all the same resistance readings on the old gas valve I already removed.
Fusible Link:
  • The fusible link wires (AKA exhaust temperature switch) had visible charring at the connectors
  • I cut the ends off and replaced them with new connectors
  • I confirmed there is continuity between the terminals of the fusible link
I believe this summarizes everything done and tested to date. Any ideas are welcome.
 

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  • Valve Voltage Test.jpeg
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  • Resistance at Solenoid Terminals.jpeg
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JamesW

TFP Expert
Mar 2, 2011
25,004
Get a 24 volt low wattage light and see if the voltage will light up the light without having the voltage drop out.

If you don't have a 24 volt light, you can use (2) 12 volts lights in series.
 

1poolman1

In The Industry
Jul 14, 2014
98
Sacramento
Two things to check; 1. Is there another gas cock besides, the blue-handled one, somewhere in the gas line, and is it open? 2. When you open the union and have the blue handle in the position it is in in your picture, do you get gas? If not, why not? You'll hear and smell it very quickly. Natural gas is not poisonous but don't leave it open for long. It would be hard to get a 7.6"wc measurement with no gas coming from the line. You can also just pull that test plug with the gas cock open and should be able to hear and smell gas. If not, you have no gas to the appliance.

I have even seen older systems that have had water get into the gas line under ground and cause the condition you are seeing.
 

b2cperson

Member
May 7, 2021
12
North Carolina
Two things to check; 1. Is there another gas cock besides, the blue-handled one, somewhere in the gas line, and is it open? 2. When you open the union and have the blue handle in the position it is in in your picture, do you get gas? If not, why not? You'll hear and smell it very quickly. Natural gas is not poisonous but don't leave it open for long. It would be hard to get a 7.6"wc measurement with no gas coming from the line. You can also just pull that test plug with the gas cock open and should be able to hear and smell gas. If not, you have no gas to the appliance.

I have even seen older systems that have had water get into the gas line under ground and cause the condition you are seeing.
Here is what I have done so far.
  • Removed the 3/4 male plug from the end of the black pipe supply. I turned on the gas valve and the gas rushed out. This was the one located between the gas pressure regulator and the gas valve. There did not seem to be any obstructions.
  • All gas valves are open. It the same supply that feeds both my HVAC and outside grill. Neither of those has had any issues.
  • I also disconnected the gas union located on the curved piece of black pipe located between the outlet of the valve and the inlet that supplies the combustion chamber. I then turned on the heater. The ignitor glows I hear a clicking, sounds like a relay on the ignition control baord. I NEVER smell any gas being released through the valve, which I should have given I disconnected the union.
  • I also connected my digital manometer to the 1/8" plug on the inlet side of the gas valve to measure the static pressure, which was 7.6" wc
I remain stumped as to why the gas valve is getting voltage but not opening to release gas.
 

JamesW

TFP Expert
Mar 2, 2011
25,004
I remain stumped as to why the gas valve is getting voltage but not opening to release gas.
You say that there is no measurable voltage when the wires are attached.

That means that the valve is shorting out or the power is dropping out for some reason upstream.

Try to power a 24 volt AC light to see if the power drops out or actually lights up the light.

If the light bulb lights up, then it would seem that the valve is the problem.

If the light does not light up, then the upstream power supply is the problem.

Measure the voltage and current as the lights light up.

12 volts light bulbs are easy to find.

Put two in series to create a 24 volt load.


 

gocubs418

Well-known member
May 3, 2016
389
Dallas/TX
Any other ideas for me? The gas valve is clearly getting voltage but does not activate the solenoid. This would seem to suggest a bad gas valve but I already replaced the gas valve with a brand new one. What are the chances I received a bad gas valve out of the box?

Is it possible the gas valve is not receiving enough amperage to activate the solenoid? I know the brown and yellow wires are providing 26.2 V AC to the gas valve as part of the ignition sequence.

I am at a loss and could use some guidance.
Wrong post. Whoops.