Jandy Lxi 400 ignition fault.

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M

macdenewf

Well-known member
Oct 27, 2012
73
Spring, TX
Hi. I was about to post in a previous thread ( 2020) but was given a suggestion to start a new thread.
I have an intermittent problem.
The last 2 times I went to use my hot tub my heater failed to work and it flashed “check ignition “. I went out tonight after reading some of these posts to try and get a better description of the problems and after a few failed attempts at starting it finally remained on
Rather than use the remote I put it on service mode. Let the pump get to full speed then selected the heater. The fan came on for about a half a minute then the heat kicked in. About 10 seconds later the heat kicked out. Fan remained on. About 30 more seconds passed and the heat started again. Ran for 10 seconds the kicked off again. 30 more seconds then the heat kicked in again and it stayed on.
Pretty much the same thing happened the last time I tried the heater but after 3 tries it stopped all together then flashed the check ignition. Have to assume it did the same the 1st time it failed to work. It flashed check ignition then too.
Probably completely unrelated but about a month ago my dog was chasing something by the heater ( gecko perhaps ) and thought it was a good idea to chew through a wire harness. It ended up being the high limit wire harness switch assembly (r0457400). I replaced that and it worked fine after. Though I must admit. I didn’t have that white compound they put on the end of each sensor ....conductive grease I expect.
Also worth noting. This was a week after the cold temps we had in Houston a few weeks back. Got down to 10f. No leaks as the pump
Ran continuously for a few days but maybe something crawled into the heater.
I use the hot tub fairly regularly. Minimum twice a month and some times even more frequently so I don’t expect it’s from sitting idle.
Never had gas supply issues in the past so don’t expect it’s that either.

The heater has been relatively dependable. Would love to figure out why the last 2 of the 3 times I went to use it it wouldn’t work.


Appreciate any advice.
Thanks.
mac.
 
Mac,

Heaters can be frustrating but hang in there we are usually able to find out the cure. First a couple questions. When you say heat do you hear the gas valve click then feel heat in the exhaust and smell gas? Also can you look at the Fenwal, it has a red light that blinks a certain number of times (1,2,or 3) after the unit shuts down. How many blinks do you see? This can help confirm the issue. When your unit goes through the startup sequence and turns on the igniter and then lights a flame it usually means you don't have a problem with the sensors in the safety circuit. So the problem is likely to be gas supply or the flame sensing circuit. Start by checking the ground wires on the electrical raceway and if this doesn't work you can easily try grounding the burner base to the raceway. This is described in Alan's reference above. Almost all heaters now use flame sensing to keep the burner lit. It's very reliable in most cases but it is also very sensitive. The way it works is that the igniter stays powered after the burner lights and a very tiny current (millionth's of an amp) flows through the ionized particles in the flame to the burner. The Fenwal detects this signal to be sure the flame is lit and if it doesn't detect it closes the gas valve. The signal has to pass through the burner and frame ground back to the Fenwal. So any of several ground connections can cause this. You eliminate this issue if you run the extra ground wire. Please let us know what you find. There are several other things to check. Have you by any chance had lightning strikes in your area recently?

Chris
 
Mac,

Have you able to got your problem fixed? I also having the same problem with my LXi 400 heater; it was working fine last season.

Not sure it is related to the winter freeze last Feb. or not; my front & rear header of the heat exchanger were cracked. I have to re-pipe and have the heater bypass until I was able to find a used replacement part. After reconnect everything, it had a Fuselink sensor fault; cleared after sensor replaced it. However, now it is having IGN Control fault; it will start up and running fine for about an hour and stop working with the IGN fault. I already have the sensor cleaned but did not fix the problem.

Thanks
 
IGN fault usually means one of the safety sensors is either malfunctioning, or has corroded connectors, or is working properly and keeping the unit from a dangerous condition. I had similar fault and was able to isolate by letting it go through the start sequence and wiggle connections at the sensors. Once you wiggle the one that lets it complete the cycle you have your problem. Didn't look especially dirty but cleaning and spray with Corrosion Block solved the problem. In my case it was the air flow sensor. If this doesn't work, please see the trouble-shooting section in the manual above that Allen provided links for above.

I hope this is helpful.

Chris
 
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So. My Jandi 400 Lxi is acting up again. When I select heat it will start the sequence, fan cones on. Heat fires for about 4 seconds ( can feel the heat and smell the gas ) then stops. It does this 3 times then flashes ignition fault. Over the past year I’ve replaced the 24 v transformer, The high limit harness sensors zodiac RO457590 and the power distribution board.
when I replaced the high limit sensors I didn’t have any of that white grease. I wonder if I need to pull them, clean and repack? What if that grease? Anyone know.
thanks.
 
Mike,

If you make it all the way through the start cycle to light the burner the ignition control has already read all the sensors as "safe". The problem is more likely with the flame sensor, sensor ground, or possibly a loose connection. After it stops, how many flashes are you getting on the Fenwal module's red light?

Chris
 
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