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  1. #1
    Join Date
    May 2011
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    CA
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    123

    Condeser fan not running

    So I'm dying to beat the journeyman I work with (well, the journeyman I call when there's a problem) to the solution to a problem. Before the weekend I always check on our condensing fans on the roof. We have a 2 Hussmann Protocol HE units with 6 copeland scroll compressors each, 404a. The air-cooled condensing units (called the "Levitator" or "Leviton" series by Krack...I believe they're sold with all Protocol systems?) have a total of 12 fans, 6 for each rack. So I go up on the roof to check proper rotation (we had one single phasing before...nobody caught it and the whole rack shut down b/c of high head pressure, thus why I check them). The fans cycle on one at a time starting with fan #1 at the header end. So I noticed that fan #1 wasn't running, but fans 2, 3, and 4 were. I opened the motor control panel on the condensing unit and noticed the contactor for fan #1 wasn't pulled in. Went down and checked the protocol, the head pressure was at 160 and the display said fan #1 on this rack was "ON". Had a coworker look at the protocol display while I went back up on the roof, I watched the fan (not running) but he said protocol display still said fan #1 on this rack was "ON". I pushed in the contator and the fan cycled on. Called our tech, he said we'll take care of it next week b/c heat isn't an issue and the remaining 5 fans should be able to keep the head pressure down.
    I can't figure this out and want to. I'm guessing it's just either a) coil is bad for the contactor and won't pull in, or b) some electronics issue with the protocol controls...but I won't mess around with them. I just want to see if i'm barking up the right tree...

  2. #2
    Join Date
    Feb 2006
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    USA
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    4,381
    check the voltage at the contactor coil before he gets to work lol

  3. #3
    Join Date
    May 2011
    Location
    CA
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    Quote Originally Posted by hvac wiz 33 View Post
    check the voltage at the contactor coil before he gets to work lol

    Damn. . I didn't do that. Just automatically assumed.

    Ok but let's say it DOES have voltage. I'm guessing I could Ohm it to see if the coil is still good, right? Thus eliminating the contactor entirely?

  4. #4
    Join Date
    Aug 2002
    Location
    Orange County CA
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    1,084
    Quote Originally Posted by Iceneck View Post
    Damn. . I didn't do that. Just automatically assumed.

    Ok but let's say it DOES have voltage. I'm guess I could Ohm it to see if the coil is still good, right?
    yes

  5. #5
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    Feb 2006
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    USA
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    he might b reading this thread lol

  6. #6
    Join Date
    Jun 2010
    Location
    Miami
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    258
    Best to move fast. If the coil has voltage and the contactor won't pull in there are only a few reasons. If you are lucky the coil is open. If you are unlucky the coil is shorted and this could take out the entire condenser package. I would need to know more....such as is the contactor just a contactor or is a motor starter....which is a contactor plus an overload relay. If it is a motor starter and the motor is drawing too many amps the O.L. relay will open the control circuit to the coil.

    So depending on what you have, and assuming you have coil voltage, it could be just a bad coil or it could be a bad motor. When checking coil voltage, if you have an overload relay, be sure to check voltage on both sides of O.L. relay.

    Best not to be pushing contactors in until you ohm/megger motors. Push one in with a dead short on the load side and very bad things could happen. We don't want you getting fried!!!

    If you want brownie points....and you only have contactors....suggest upgrading to motor starters. They will protect motors from single phase conditions, phase reversals, low voltages, and motors that over amp (depending on motor starter). That could mean the difference between the entire rack going down and a bunch of motors getting fried or just throwing a new set of bearings in one motor.

  7. #7
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,462
    I don't know about the protocol HE, but some of the older ones had clear relays on the control board in the protocol so you could see if the relays were pulling in to send power to the contactors at the condensers.

  8. #8
    Join Date
    May 2011
    Location
    CA
    Posts
    123
    Thanks for all the replies...

    Russ--I don't think there are any relays on the Protocol control board, at least none that I could see. I could take a pic and post it. Just thinking out loud, though...It has to have some sort of relay, doesn't it? I mean (and I'm just guessing here) the cpc (emerson/einstein) wouldn't transmit 120v signals, would it? And from the guage of the wires entering the motor control panel on the condensing unit I don't think there were any low volage wires going into it. Which would mean there would have to be some sort of a relay somewhere between the cpc and contactor, right? But I've never seen any sort of "ice cube" relay anywhere in the protocol control board, or the motor controls on the condensing unit.

    What worries me is that on the motor control cover on the condensing unit, there is a manufacturer's sticker that says: "NOTICE: THE FIRST FAN ON THE HEADER END, OR SET OF FANS, MUST BE ON WHEN ANY COMPRESSOR IS RUNNING". I'm guessing this probably has to do with (and I'm going to say this rather sheepishly, as it's only a guess and I'm a rookie) that it has something to do with the capacity of the condenser? Guess I should also say, although I don't know how relevant it is, that we have floating head pressure on this rack...

  9. #9
    Join Date
    Sep 2002
    Posts
    12,664

    First look for voltage at the offending contactor's coil terminals

    First look for voltage at the offending contactor's coil terminals. If you have it - replace the contactor. If you are not sure what the control volatge is supposed to be - check the voltage at a fan contactor which is already pulled in.

    If you don't have control voltage to the #1 contactor coil - jump control power over from the #2 fan contactor's coil to keep the system up and going until you can sort out why you have no control voltage to #1.

    Do it this way: disconnect both #1 coil wires, and insulate them both from shorting to each other or to anything else. Then run two new wires over from the two terminals on the #2 coil.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  10. #10
    Join Date
    Feb 2008
    Location
    California
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    2,066
    What you have here is a simple issue. with that said...

    IMO...you have found what appears to be a problem with your system. Congratulations.

    Now call your service provider for qualified service. IT JUST MAY SAVE YOUR LIFE. Your condenser most likely is running 208 volts up to 480 volts. It would be a shame for un-experienced hands to get electrocuted.

    continue to watch over the experienced technicians shoulder and continue your quest to go to school or get a job with the experienced technicians company.

  11. #11
    Join Date
    Sep 2002
    Posts
    12,664

    Isn't this an inside job ?

    I had the impression that this was all inside-work being done by on-site guys.

    Is that accurate or untrue?

    PHM
    ------




    Quote Originally Posted by Phase Loss View Post
    What you have here is a simple issue. with that said...

    IMO...you have found what appears to be a problem with your system. Congratulations.

    Now call your service provider for qualified service. IT JUST MAY SAVE YOUR LIFE. Your condenser most likely is running 208 volts up to 480 volts. It would be a shame for un-experienced hands to get electrocuted.

    continue to watch over the experienced technicians shoulder and continue your quest to go to school or get a job with the experienced technicians company.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  12. #12
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    Yes.

    He is an employee of the store and he inspires to be a refrigeration technician. Currently has no schooling or formal on the job training. He has been shadowing the service contractor and learning bits and pieces of information.

    I think he is in over his head on this one. I think its good that he has realized a problem. I don't think its a good idea for him to try and repair the issue. And certainly not be disconnecting wires and jumping anything or pushing in contactors. For all we know he may have a VSD on this thing and he just pushed in a bypass contactor while this thing is in inverter mode or a grounded/shorted motor. either situation possibly leaving him with an explosion, in his face.

    He should stick to clearing drains, repairing water leaks and de-icing cases and call all other issues into his refrigeration contractor so he can learn about the trade and then that will hopefully help him make an educated decision to either to go to school or get a job in the business.

  13. #13
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,462
    Quote Originally Posted by Iceneck View Post

    What worries me is that on the motor control cover on the condensing unit, there is a manufacturer's sticker that says: "NOTICE: THE FIRST FAN ON THE HEADER END, OR SET OF FANS, MUST BE ON WHEN ANY COMPRESSOR IS RUNNING". I'm guessing this probably has to do with (and I'm going to say this rather sheepishly, as it's only a guess and I'm a rookie) that it has something to do with the capacity of the condenser? Guess I should also say, although I don't know how relevant it is, that we have floating head pressure on this rack...
    They want that fan on all the time to prevent damage to the condenser from thermal stress from from the big temp swings that would occur if you cycled it. The one protocol I service has a fixed head at 210 and cycles fans 2 and 3 to maintain that. If it drops below about 200 the condenser flooding valves try to bring the pressure up. When the refrigerant is low that doesn't work, the controller cycles the first fan off.

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