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  1. #40
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    Quote Originally Posted by sdtech View Post
    I'm a new member trying to help others, Anyway you have your control voltage mostly it is 24VAC. This how the CLO does the s'tats calls for cooling the contactor energized on terminal 3 also energize the CLO logic circuit, must see at least 1.5 amps or the module will lock out. If the sensing loop does not sense amperage its open the contact between 2 and 3 and close contact 2 and X locking out the unit until 24VAC reset. Most Carrier unit has this CLO to monitor one leg of the compressor circuit. good luck
    SD,
    This is correct. Y1 Blue wire goes thru ecno plug and comes out Gray goes to #2 terminal on 1st CLO. Goes thru CLO to n/c contacts at terminal #3. Then leaves CLO on to HPS than LPS then #1 compressor contactor. Terminal #1 Brown is com. for CLO's & White is x terminal normally open and goes back to connection board. Y2 Yellow wire goes thru ecno plug and comes out Orange goes to #2 terminal on 2nd CLO. And repeats as above.
    Question is how can it measure any compressor leg amps if the contactor has never engaged ?
    Also if OP has 24 volts @ contactor it already made it thru all the hoops described above.
    Now if the contactor engaged then disengaged because of no amp read i would look at the CLO.
    Ever have a car with the lights working but when you try to start they dim ? You could read 12 volts @ the battery but have no cranking AMPS.
    Just my

  2. #41
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    The CLO is preventing the unit not to run there is other problem in the control circuit like you described like economizer there is a problem not allowing the cooling to run stuck 100% open may be still economizer mode using OA for cooling, and there is temp.disc behind econo actuator may be bad. You can bypass the CLO or putting a jumper wire just see if it work, 100% it works unless you don't have other problem, Carrier put those for safety. to answer your question of course you can not measure comp. amp not energized.

  3. #42
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    Quote Originally Posted by sdtech View Post
    The CLO is preventing the unit not to run there is other problem in the control circuit like you described like economizer there is a problem not allowing the cooling to run stuck 100% open may be still economizer mode using OA for cooling, and there is temp.disc behind econo actuator may be bad. You can bypass the CLO or putting a jumper wire just see if it work, 100% it works unless you don't have other problem, Carrier put those for safety. to answer your question of course you can not measure comp. amp not energized.
    SD,
    OP said he had 24v at the contactor coil. So i would think that the CLO is functioning correctly or it would not send 24v thru it on to contactor. Yes or no ?
    P.S.
    To dis enable the CLO just pull the Brown wire @ terminal # 1 as GT said.

  4. #43
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    Apr 2010
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    Dear VTP99,
    If you do have 24VAC on your contactor coil and line voltage 3ph or 1ph if the coil is good its should pull in and compressor will run i don't see no problem and the answer to your question yes and pulling out brown you can disable it, I apologized did not know you have other question sorry my friend.

  5. #44
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    Quote Originally Posted by VTP99 View Post
    SD,
    OP said he had 24v at the contactor coil. So i would think that the CLO is functioning correctly or it would not send 24v thru it on to contactor. Yes or no ?
    P.S.
    To dis enable the CLO just pull the Brown wire @ terminal # 1 as GT said.
    I know he did say that voltage was good at the coil, but there may be low current due to the CLO.

    Not a lot is published about this CLO device, but what I have seen tells me that the unit DOES run when reset by pushing in the contactor, and when that happens, the current sensing loop reacts to the current through that wire that passes through the loop, and the lockout circuit is reset. Then, the unit runs until a fault is detected (let's say a low pressure switch opens) and the contactor opens and, voilà, a lockout.

    When I see this behavior, I start looking for safeties that open and lockout the compressor. I've never taken the time to see if a voltage is still measurable at the contactor coil. There may indeed be 24 volts at the coil, and yet, the CLO may limit its current so the coil cannot pull in the contactor.

    The bottom line, IMHO, is that this behavior is consistent with a compressor lockout, but more testing is needed. When you are presented with a puzzle like this the first couple of times, you may not be able to think it through clearly. As you come to understand what is actually happening, your approach becomes more clear, and your ability to accurately gather the info and interpret it gets better and better.
    [Avatar photo from a Florida training accident. Everyone walked away.]
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  6. #45
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    Quote Originally Posted by sdtech View Post
    Dear VTP99,
    If you do have 24VAC on your contactor coil and line voltage 3ph or 1ph if the coil is good its should pull in and compressor will run i don't see no problem and the answer to your question yes and pulling out brown you can disable it, I apologized did not know you have other question sorry my friend.
    No need to apologize. Thank you for your response. Glad you found this site. All of us are here to learn i hope. Also thank you for clarifying. Are you in the trade ? Probably a stupid question. I'm sure you know about Pro Membership.

  7. #46
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    Quote Originally Posted by timebuilder View Post
    I know he did say that voltage was good at the coil, but there may be low current due to the CLO.

    Not a lot is published about this CLO device, but what I have seen tells me that the unit DOES run when reset by pushing in the contactor, and when that happens, the current sensing loop reacts to the current through that wire that passes through the loop, and the lockout circuit is reset. Then, the unit runs until a fault is detected (let's say a low pressure switch opens) and the contactor opens and, voilà, a lockout.

    When I see this behavior, I start looking for safeties that open and lockout the compressor. I've never taken the time to see if a voltage is still measurable at the contactor coil. There may indeed be 24 volts at the coil, and yet, the CLO may limit its current so the coil cannot pull in the contactor.

    The bottom line, IMHO, is that this behavior is consistent with a compressor lockout, but more testing is needed. When you are presented with a puzzle like this the first couple of times, you may not be able to think it through clearly. As you come to understand what is actually happening, your approach becomes more clear, and your ability to accurately gather the info and interpret it gets better and better.
    Time, My question is how could the CLO limit. It either allows low voltage to pass thru terminal 2 to 3 or it opens 3 and closes x and goes back to connection board. Now if a lock out is initiated because of a fault there would no longer be 24v @ the contactor. Were as OP says there is voltage there.

  8. #47
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    Quote Originally Posted by VTP99 View Post
    Time, My question is how could the CLO limit. It either allows low voltage to pass thru terminal 2 to 3 or it opens 3 and closes x and goes back to connection board. Now if a lock out is initiated because of a fault there would no longer be 24v @ the contactor. Were as OP says there is voltage there.
    Well, it could be that 1) the voltage was not actually measured at the contactor, or 2) it was measured after being reset, or 3) there is still a voltage present at the coil, but the lockout board limits current so it cannot pull in.

    I was able to do a search and find a description of the board operation, and I discovered that a minimum of 1.5 amps must be sensed by the current loop. So, if a refrigerant charge was lost, and current dropped below that point, it would lock out the board. The site was not a Carrier site, and there could be more to it. I'm going to have to grab one of these from a scrapped unit now, and bench test it.

    Oh, and the board resets if the 24v feed is lost, and of course, that happens if the power to the unit is turned off or the call for cooling is withdrawn.

    That said, I can tell you that it is not difficult to design a lockout that merely reduces current, and allows the voltage to be measurable with a high impedance meter, like most of us use nowadays.

    I'm sure the op is going to look at this again, and hopefully, he will come back and post his findings.
    [Avatar photo from a Florida training accident. Everyone walked away.]
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  9. #48
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    Quote Originally Posted by timebuilder View Post
    Well, it could be that 1) the voltage was not actually measured at the contactor, or 2) it was measured after being reset, or 3) there is still a voltage present at the coil, but the lockout board limits current so it cannot pull in.

    I was able to do a search and find a description of the board operation, and I discovered that a minimum of 1.5 amps must be sensed by the current loop. So, if a refrigerant charge was lost, and current dropped below that point, it would lock out the board. The site was not a Carrier site, and there could be more to it. I'm going to have to grab one of these from a scrapped unit now, and bench test it.

    Oh, and the board resets if the 24v feed is lost, and of course, that happens if the power to the unit is turned off or the call for cooling is withdrawn.

    That said, I can tell you that it is not difficult to design a lockout that merely reduces current, and allows the voltage to be measurable with a high impedance meter, like most of us use nowadays.

    I'm sure the op is going to look at this again, and hopefully, he will come back and post his findings.
    Time,
    OP said he had good voltage at contactor in post #4. I see the CLO as a protection device to monitor compressor power supply. On 3 phase to protect against single phasing. The unit already has protection for high & low pressure. Just to clarify my writing here, I'm am just thinking this from looking at the wiring diagram. You could very well be right that that board limits low voltage current. I just don't see that from the wiring drawing. So i guess the real question is does this device limit or just turn on turn off. Test that board and lets find out.

  10. #49
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    Quote Originally Posted by VTP99 View Post
    Time,
    OP said he had good voltage at contactor in post #4. I see the CLO as a protection device to monitor compressor power supply. On 3 phase to protect against single phasing. The unit already has protection for high & low pressure. Just to clarify my writing here, I'm am just thinking this from looking at the wiring diagram. You could very well be right that that board limits low voltage current. I just don't see that from the wiring drawing. So i guess the real question is does this device limit or just turn on turn off. Test that board and lets find out.
    Ok. The only problems I have had with compressor lockout were due to low charge.

    I see what he said in post #4. I'm suggesting that may not be correct.

    Talk to you guys later.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

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  11. #50
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    Quote Originally Posted by ascj View Post
    But if you push in the contactor with the CLO locked out, the contactor will engage and remain engaged.
    You know I have never seen this happen on this kind of unit. Can you explain more on how this can happen? TIA
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  12. #51
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    Dear VTP99,
    You asked me if i'am on the trade yes, from San Diego area this is good site thank you for asking friend

  13. #52
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    Welcome. I'd say that most of us enjoy the sharing of ideas. I try to learn something new every day.
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    2 Tim 3:16-17

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