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Thread: LAARS LX AGC service code

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    LAARS LX AGC service code

    ok here is what I have. Turn on heater fan runs no ignition, no smell of gas. After 3 cycles flashing service code AGC. My Gas supply is ok. My pool is functioning properly. I don't have 24v at the gas valve when heater is turned on. I have no 24v at the purple wire of the ignition control terminal which powers the ignition cycle. I can't be sure it is the controller because the gas valve has to satisfy the controller to turn on the ignition cycle. Anyone have a problem similar to this?
    8500 gal bean shaped pool with spa attached.

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    Re: LAARS LX AGC service code

    So if you don't have 24v at the valve, then its the control module or board.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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    Re: LAARS LX AGC service code

    make sure the fan proving switch is closing.
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: LAARS LX AGC service code

    Quote Originally Posted by danpik View Post
    make sure the fan proving switch is closing.
    hi danpik how do I test this switch? The fan runs fine through the cycle.

    - - - Updated - - -

    Quote Originally Posted by ps0303 View Post
    So if you don't have 24v at the valve, then its the control module or board.
    Is the thermostat serviceable without replacing the whole board? I have the diagnostic troubleshoot flow chart. If the fan runs it skips down to ignition sequence. I dont have 24v at the purple wire from the ignition control board. It then says to replace thermostat.

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    Last edited by rc477; 09-07-2015 at 11:05 AM. Reason: rdundancy
    8500 gal bean shaped pool with spa attached.

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    Re: LAARS LX AGC service code

    You will need to connect a jumper wire between the terminals This can be a bit tricky though if the unit is a newer one. On older control systems, one could pull both wires from the switch and jumper them together. If the unit worked, the problem was somewhere in the fan, vacuum tube from the fan to the switch or the switch itself. On newer systems, the control board looks for the circuit to be open at start, then closed. It actually looks for the close event to happen after power is applied to the fan circuit. This is to prevent someone from permanently jumping out the switch. If the fan is not drawing enough air/vacuum, it will not close the switch. This could be a few things...The vacuum switch could be bad, the tube running from the fan housing to the switch could be leaking, the ports on the fan housing and/or vacuum switch could be plugged or the fan itself could be bad.
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: LAARS LX AGC service code

    Quote Originally Posted by danpik View Post
    You will need to connect a jumper wire between the terminals This can be a bit tricky though if the unit is a newer one. On older control systems, one could pull both wires from the switch and jumper them together. If the unit worked, the problem was somewhere in the fan, vacuum tube from the fan to the switch or the switch itself. On newer systems, the control board looks for the circuit to be open at start, then closed. It actually looks for the close event to happen after power is applied to the fan circuit. This is to prevent someone from permanently jumping out the switch. If the fan is not drawing enough air/vacuum, it will not close the switch. This could be a few things...The vacuum switch could be bad, the tube running from the fan housing to the switch could be leaking, the ports on the fan housing and/or vacuum switch could be plugged or the fan itself could be bad.
    alright, a little more focused. I checked voltage at the black wire going to the water pressure switch. I have 28.8VAC at the switch and 4VAC on the other side. Model is LX250N year is 2002. I would think each safety is fed from from the preceding one because of the higher than normal voltage on the black wire. If they all worked the additional load should get back around 24VAC. Am I safe to say the water pressure switch is the culprit?
    Last edited by rc477; 09-07-2015 at 05:35 PM. Reason: update
    8500 gal bean shaped pool with spa attached.

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    Re: LAARS LX AGC service code

    bttt
    8500 gal bean shaped pool with spa attached.

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    Re: LAARS LX AGC service code

    Quote Originally Posted by rc477 View Post
    alright, a little more focused. I checked voltage at the black wire going to the water pressure switch. I have 28.8VAC at the switch and 4VAC on the other side. Model is LX250N year is 2002. I would think each safety is fed from from the preceding one because of the higher than normal voltage on the black wire. If they all worked the additional load should get back around 24VAC. Am I safe to say the water pressure switch is the culprit?
    That is not quite how it works. (voltage won't "pile up") Yes, most safety switches are daisy chained. I am suspecting you are using a digital multimeter and reading some phantom voltage on the open end of the switch. 28 volts is not unusual as transformers don't regulate their output. If you jumper the two wires together at the pressure switch the unit may fire if the switch is bad. DON'T do this as a fix.
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

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    Re: LAARS LX AGC service code

    I have a new switch coming in tomorrow. I'll post back then.
    Does a new switch come adjusted from the factory?
    8500 gal bean shaped pool with spa attached.

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    Re: LAARS LX AGC service code

    Do not make any adjustments to the pressure switch. Also, you verified that you have a clean filter right? I've seen people think it was a bad switch because they jumped it and the heater worked only to find out that the filter was dirty and the new switch didn't resolve the issue.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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    Re: LAARS LX AGC service code

    Quote Originally Posted by ps0303 View Post
    Do not make any adjustments to the pressure switch. Also, you verified that you have a clean filter right? I've seen people think it was a bad switch because they jumped it and the heater worked only to find out that the filter was dirty and the new switch didn't resolve the issue.
    squeaky clean. I service and check my basket every morning, check pump pressure and volume. When I pull off the old pressure switch I will verify that transfer tube pressure is correct before I install the new switch. Thanks for posting all help and input is much appreciated.
    8500 gal bean shaped pool with spa attached.

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    Re: LAARS LX AGC service code

    I received the new pressure switch today and installed it. I had 26VAC from the water pressure switch to the blower pressure switch and after the timer sequence the heater fired right up.

    What threw me while I was looking over the manual was no PRESS SW flashed as is mentioned in the diagnostic guide. Other than knowing that all of the safety switches are in series i'm not sure of the logic that the processor is using. I'm wondering if there is a diagnostic mode the processor can be put into.

    Anyway, I learned a lot about my heater and thanks for all of the help!
    8500 gal bean shaped pool with spa attached.

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