I am helping a friend troubleshoot his pool heater (Jandy 400). His unit is getting a single flash LED light which indicates an air flow fault. After the unit shuts down the display indicates Fault- Check IGN Control. I checked the obvious signs like blockage (inlet and outlet). Put meter across air flow switch and water pressure switch to ensure contacts were being made up during startup, checked continuity on ignitor which was fine. I can feel air flow in the discharge but not sure what is sufficient but if air flow switch contact is closing I assume I have sufficient air flow. I then pulled the leads going to the ignitor and put a meter across the module outputs and I have no juice going to the ignitor after the unit starts and goes thru it’s purge sequence. I then thought it might be something in the Fenwal ignitor module so I replaced it, still getting the same error code and results. Is there something else I should be checking or could it be something wrong on the Universal Controller Power Interface Board. Any thoughts or help would be greatly appreciated.
No juice to the ignitor
- Thread starter BillK1955
- Start date
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- Tags
- jandy pool heater
- Oct 25, 2015
- 5,141
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Sounds to me your air switch is actually failing. You can't just short the leads on the air switch. The Fenwal actually looks for a change after the fan is powered up. The only way to test this is to short it after the fan starts. It's hard to do and catch it just right. I would check the rubber tubes to be sure they aren't plugged or that one hasn't come loose. What model is it?
Chris
Chris
Please explain do you mean testing the fan contacts on the fenwal after fan starts?
- Oct 25, 2015
- 5,141
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Most of the sensors can be temporarily shorted to see if they are causing the failure in the ignition sequence. This is not the case for the air switch which is looking for "proof" there is sufficient air flow for a period of time in the fire box to prevent an explosive mixture. So the Fenwal looks for a change of state on the switch AFTER the fan starts. If the switch is shorted before the fan starts the Fenwal will not detect a change and will therefore not allow the ignition sequence to proceed so no power will be delivered to the igniter and the gas valve relay will not be energized. I learned all this the hard way when diagnosing my Jxi heater after a lightning strike. I've read about failures in the air tubing, tiny amounts of corrosion, and even plugging of the connectors by mud dobbers that also cause this. The air switch itself is extremely reliable. I've only read one case where it was proven to have failed.
Just to complete this response it's important to mention safety. Shorting contacts of any sensor can be extremely dangerous if the sensor is actually doing it's job to prevent a dangerous situation in the ignition cycle. Be extremely careful, respect the massive potential energy release with even small amounts of gas. Only perform these kinds of tests momentarily and only if you are experienced, and trained in gas systems. If not get a qualified gas plumber to perform this work.
I hope this is helpful.
Chris
Last edited:
Thanks Chris. The model is Jandy jxi400n. I did not short the air flow switch but was looking for 24VAC across the switch leads. Before start no voltage, after start, approx. 24VAC across switch leads. Perhaps I misunderstood how switch works. When l look at the schematic it shows a normally open contact And I assumed once the fan started and I see 24VAC across the leads that this contact has gone closed and therefore correct air flow has been detected. The tubing looks ok but I did not disconnect and do a very thorough check. I am incorrect on my assumption on voltage reads?
- Oct 25, 2015
- 5,141
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
If you waited until a few moments after the fan started you should see the 24 vac. I believe you can also check this on the connections at the Fenwal (it's been a while since I've done this). You can also blow gently on the air hose to see if the switch engages. There are a couple online videos that show this... doesn't take much air pressure.
Chris
Chris
- Oct 25, 2015
- 5,141
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Also, please note the air tubing under the blower motor can easily become detached or damaged and you won't see it. Please check this to be sure it's not your problem.
Chris
Chris
swamprat69
Well-known member
If you are reading 24V across the switch contacts after the fan/blower starts and runs, then the switch is not closing when the fan/blower is running. A closed NO switch would read 0 volts across the switch contacts when the fan/blower is running.
