LXi400 Ignition Fault

[ladsjohn]

I have a Jandy LXi400 heater that gives me a "FAULT - CHECK IGN CONTROL" when I turn on the heat.
I've read a few threads and followed the troubleshooting guide (https://www.parts4heating.com/v/vspfiles/Troubleshooting/LXiTS.pdf) which led me straight to Step13.

Rather than getting 24VAC at the air pressure switch; I'm getting about 8VAC. As such; I replaced the air pressure switch. No difference. Still only getting 8VAC.
Any ideas what to try next?

The exact symptom is; I turn on heat remotely (using my PDA). The blower comes on and I hear the ignition module click 3 or 4 times (or more likely it's the gas valve that's clicking open) before the fault appears and the blower shuts off.
One thing that I'm doing slightly differently is where it says "24 VAC between Orange (NO) wire at the Air Pressure Switch and Yellow (1) wire on the Transformer?" ; I'm actually testing against the grounding screw on the front panel instead of the wire directly on the transformer.
The transformer seems to be hard to reach and I figure the Yellow (1) wire on it goes to ground anyway. I guess I should test as instructed but I don't see an easy way to reach the transformer.

Any and all advice, berating, bbq sauce recipes accepted. Thanks!

 

[ajw22]

How old is your heater?

Post pics of the inside of your heater.

Chances are you have rust and corrosion around your heater that is causing resistance and loss of voltage when you test to the ground screw.

CHECK IGN fault is not a problem with the air pressure switch.

You need to check your igniter, flame sense rod, and gas pressures. Check that the igniter is glowing.

Jandy LXI Heaters - Further Reading

www.troublefreepool.com

 

[ladsjohn]

Thanks. Heater is about 10 years old (and I've used it about 10 times over that period)
I've already cleaned the flame rod (it was in good shape but cleaned it with some 0000 steel wool anyway).

No obvious corrosion (see attached) but I get your point about the resistance. Current is consistently 8-10VAC in the places it should be 24VAC.

I don’t have the means to test the gas valve, but I do get a whiff of gas at the heater when the blower starts. My BBQ is also tee’ed off this line and the pressure there is a-ok.

The ignitor is glowing.

 

[MSchutzer]

I had a problem like this several years ago with my LXi 400 heater. Ignitor was fine, flame we rod was cleaned, gas valve opened momentarily with the smell of gas in exhaust, but not lightning, and then timed out after three tries.

It turned out to be cobwebs plugging the burner jet that was feeding the burner under the igniter. The other jets were open so I had gas in the exhaust, but the blocked jet in the burner under the igniter prevented the heater from firing before the gas shut off.

Your problem may be different, but this might be something else to check if all your other troubleshooting fails to turn up the problem.

 

[ajw22]

I don’t have the means to test the gas valve, but I do get a whiff of gas at the heater when the blower starts. My BBQ is also tee’ed off this line and the pressure there is a-ok.

Whiff of gas is meaningless.

A gas pool heater requires much more gas pressure then a BBQ.

To light a heater requires gas, air, and spark. You have air if the blower is running. You may have spark if the igniter is glowing. The gas needs to be checked.

If the heater initially lights but does not stay lit then you need to check for flame sensor problems.

The ignitor is glowing.

Did you phsyically check the igniter? Some have found it crumbled when they touched it.

 

[ladsjohn]

Sorry for the (very) late reply. I re-ran the troubleshooting steps more thoroughly and the problem is the hi/low limit switches. New part on the way.