Jandy/laars Lx 400 Lights Intermittently

[JackMac]

My LX400P 240vac Serial No. A99LE0181 (Propane, 2002 model) seldom lights.

I have done the following:

o Bypassed all safety switches to make sure I didn't have a safety lockout.

o Installed new gas valve and bled line.

o Measured demand voltage at gas valve (normal)

o Measured gas regulator output (14"WC . . . top end for propane)

o Measured gas pressure at valve output (on demand). Pressure present and drops to 7"WC (not unusual for an open line to the manifold); therefore, gas does flow into the manifold.

o Removed and cleaned out the gas manifold and cleaned each jet's orifice.

o Visually inspected igniter operation (using shinny metal plate as a mirror). Igniter glows bright orange when on.

o The igniter resistance checks normal and I have cleaned the flame sensor.

Results:

o Igniter comes on and then the gas valve opens (verified by manometer).

o Igniter goes back off gas valve closes.

o Cycle repeats 3 times and then I get an AGS service code.

Observation:

o It appears that the igniter comes on, but there is a delay before the gas valve opens. The valve seems to open as the igniter has almost dimmed out. That is the reason I changed the gas line regulator, thinking it may be sticking and causing the delay. The regulator is connected to a high pressure line (10 lbs) and is located just outside the heater cabinet, so it's not a feed line problem.

Questions:

o Is this delay normal or maybe there's a normal delay, but maybe it's too long? The few times the heater does light it's just before the igniter dims out. The coincidence of gas and igniter seems to be right on the edge of the light cycle.

o Possibly a control board problem? That's one thing I haven't changed out. I did pull the board, cleaned all the contacts, and insured that all wiring was sound. No change.

o Finally removed all jumpers from safety switches since this didn't seem to be a problem. Gas valve and igniter still worked the same. Still won't light.

Any suggestions appreciated and questions are welcome.

[Pool Clown]

Does the heater fire then shut off?

If it does...

What your describing sounds like the flame rectifier is not getting rectification and therefore telling the system: there is no flame, close gas valve.

[PoolGuyNJ]

Check the gas orifices. Could be some schmutz in there.

Scott

[JackMac]

Does the heater fire then shut off?

If it does...

What your describing sounds like the flame rectifier is not getting rectification and therefore telling the system: there is no flame, close gas valve.

No, once it's lit it will run until it reaches temperature, then it won't restart for the next cycle.

[JackMac]

Check the gas orifices. Could be some schmutz in there.

Scott

Cleaned the header and cleaned each orfice with a welder's tip cleaner.

[Pool Clown]

Does the heater fire then shut off?

If it does...

What your describing sounds like the flame rectifier is not getting rectification and therefore telling the system: there is no flame, close gas valve.

No, once it's lit it will run until it reaches temperature, then it won't restart for the next cycle.

But it tries to light, Yes?

[JackMac]

Does the heater fire then shut off?

If it does...

What your describing sounds like the flame rectifier is not getting rectification and therefore telling the system: there is no flame, close gas valve.

No, once it's lit it will run until it reaches temperature, then it won't restart for the next cycle.

But it tries to light, Yes?

Thanks for the reply. The gas valve opens and the igniter comes on, but the burner doesn't light. It seems that the gas valve doesn't provide gas soon enough, only after the igniter has nearly dimmed out.

[Pool Clown]

I know you cleaned the jets, but did you clean the burners too? what you describe sounds like the burner that is right below the HSI is blocked or cogged(spider web is most common), Therefore it is not allowing the gas to make it to the HSI for ignition.

Make sure you are seeing the HSI glow before the gas valve clicks open.

[JackMac]

I know you cleaned the jets, but did you clean the burners too? what you describe sounds like the burner that is right below the HSI is blocked or cogged(spider web is most common), Therefore it is not allowing the gas to make it to the HSI for ignition.

Make sure you are seeing the HSI glow before the gas valve clicks open.

Thanks, I'll pull the valve and manifold again and remove that burner (and those either side) and see if that does it. If so, I'll let you know. It may be in the morning as the better half has me plowing the garden today.

[JackMac]

I know you cleaned the jets, but did you clean the burners too? what you describe sounds like the burner that is right below the HSI is blocked or cogged(spider web is most common), Therefore it is not allowing the gas to make it to the HSI for ignition.

Make sure you are seeing the HSI glow before the gas valve clicks open.

Thanks, I'll pull the valve and manifold again and remove that burner (and those either side) and see if that does it. If so, I'll let you know. It may be in the morning as the better half has me plowing the garden today.

I decided to take the time to give the burners a shot with the air hose. I blew 150lbs of air into each burner, paying special attention to the the three below the igniter. The heater lit 3 times without failure. So, I'm hoping that was the problem, if not I'll do a thorough cleaning of the burners. Even if it continues to work ok, I will still pull the valve and manifold, remove and clean all the burners to make sure they're all clear.

Thanks in advance for the advice . . . we'll see if it does the trick, I'll update later after I've given it a good (excuse the expression) smoke test.

[JackMac]

I know you cleaned the jets, but did you clean the burners too? what you describe sounds like the burner that is right below the HSI is blocked or cogged(spider web is most common), Therefore it is not allowing the gas to make it to the HSI for ignition.

Make sure you are seeing the HSI glow before the gas valve clicks open.

Thanks, I'll pull the valve and manifold again and remove that burner (and those either side) and see if that does it. If so, I'll let you know. It may be in the morning as the better half has me plowing the garden today.

I decided to take the time to give the burners a shot with the air hose. I blew 150lbs of air into each burner, paying special attention to the the three below the igniter. The heater lit 3 times without failure. So, I'm hoping that was the problem, if not I'll do a thorough cleaning of the burners. Even if it continues to work ok, I will still pull the valve and manifold, remove and clean all the burners to make sure they're all clear.

Thanks in advance for the advice . . . we'll see if it does the trick, I'll update later after I've given it a good (excuse the expression) smoke test.

It's still giving me a problem. If I keep cycling the heater off and on, it will eventually light. Once lit it, will run until reaching temperature but not relight.

Next I'll pull the manifold and the burners and check them for blockage.