Jandy LX400 giving me fits

Jun 16, 2014
8
Fort Mill, SC
#1
I have a Jandy LX400. It was working fine a few months ago and now having an issue. I went through the troubleshooting guide and said I should replace the Ignition system and flame sensor. Both have been replaced still and issue.

- Turns on and cycles 3 times to fire
- The firebox igniter glows on each cycle
- Blower kicks on fine
- Water flow is good
- Gas blows out every time when it wont fire
- I then get the 3 lights and ignition lockout and AGS Service error on the screen.

To me it seems like its all there.. Gas, glow in the box, blower. I cant put my finger whats missing. While this unit is 12 years old, hoping to get at least one more season out of it. Any other tips would be much appreciated!

Thanks!
 

JoelFitz

In The Industry
Dec 18, 2014
134
Houston, Texas
#4
Gas pressure. If the gas valve opens and you smell gas you can rule out almost everything else. Can do a resistance test on the igniter. Cold it should be in-between 40-70 ohms. Other than that it sounds like a gas pressure issue. I haven't heard or seen an issue with the LT/LX for clogged orifices on the fuel rail like Hayward but could check them, poke with a paperclip or check the burner tubes for mud dobber nests.
 
OP
OP
T
Jun 16, 2014
8
Fort Mill, SC
#5
Gas pressure. If the gas valve opens and you smell gas you can rule out almost everything else. Can do a resistance test on the igniter. Cold it should be in-between 40-70 ohms. Other than that it sounds like a gas pressure issue. I haven't heard or seen an issue with the LT/LX for clogged orifices on the fuel rail like Hayward but could check them, poke with a paperclip or check the burner tubes for mud dobber nests.
Since the igniter actually glows (can see it through the looking glass on the firebox) I assume its fine correctly?
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,959
FL
#8
Have you added any additional gas appliances that you didn't have before? Is this natural gas or propane? If propane, make sure you have plenty of gas.

Double check your wiring and make sure there are no bites our of the wiring from rodents.
 
OP
OP
T
Jun 16, 2014
8
Fort Mill, SC
#9
Have you added any additional gas appliances that you didn't have before? Is this natural gas or propane? If propane, make sure you have plenty of gas.

Double check your wiring and make sure there are no bites our of the wiring from rodents.
Thanks for your replies, I do appreciate it.

I didnt see any other wires looking bad or frayed. I took the top off and cleaned out a few leaves from the blower exhaust, plugged it all back in. No new gas NG appliances.
 
OP
OP
T
Jun 16, 2014
8
Fort Mill, SC
#11
Here is something from the manual.

View attachment 59561
Cleaned the DE filter just in case there was something... still no fire.

disconnected the water pressure to ensure nothing was clogged in there.. clean (blew water out steady)

Checked the voltage the water pressure, all good. (29v)

What I noticed was something odd. If I put it in Service Mode and hit the pump running.. then hit Heat.. go to the heater and move it to Pool or Spa it will fire up the 3 cycles as normal but no lighting and i get the AGS service error. (what I have been getting. If turn off the Heat button at the control panel on the iAquapanel and hit the Jandy Pool or Spa selection it will immediately go to "Low Pressure" on the screen. Could be a failsafe in that mode.. not sure.

I had my GUI replaced last season, I highly doubt it would go.

Still have to figure how to do a pressure test for the NG.

Im about ready to toss this and go with the newer replacement... ugg.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,959
FL
#12
If you haven't added any new gas appliances then I would hope you haven't lost any gas pressure. You would need a manometer to read gas pressure. In the manual for this unit I believe they talk about reading it and where. Usually as it comes into the heater and then after it pass by the gas valve, manifold side.

Here is a link to the manual. https://www.parts4heating.com/v/vspfiles/images/pdfs/JandyLXLT.pdf
 
OP
OP
T
Jun 16, 2014
8
Fort Mill, SC
#13
If you haven't added any new gas appliances then I would hope you haven't lost any gas pressure. You would need a manometer to read gas pressure. In the manual for this unit I believe they talk about reading it and where. Usually as it comes into the heater and then after it pass by the gas valve, manifold side.

Here is a link to the manual. https://www.parts4heating.com/v/vspfiles/images/pdfs/JandyLXLT.pdf

Just to give you an update, I had someone check the gas pressure and it was through the roof. His meter pegged. We then replaced the regulator valve on the supply side and it works perfect!
Thanks for your help!
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,959
FL
#14
So the gas valve was getting locked up due to over pressure. This is a classic example of an issue that requires a hands on approach.

Glad you had someone come over and look at things. It isn't always easy to diagnose thru the internet.