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Thread: carrier RTU

  1. 04-25-2010, 02:56 PM #1
    ccservicefitter
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    carrier RTU

    Any thoughts on disabling the algorithm on a comfort link for the condensing fan motor?? Why didn't they just add a high pressure transducer to turn it on..
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  2. 04-25-2010, 03:52 PM #2
    y7turbo
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    Why would you want to do that?

    i know the condenser thermisters always fail, but thats no reason to change something from OEM.
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  3. 04-25-2010, 04:11 PM #3
    Dallas Duster
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    Makes me wonder what your talking about , I'm thinking there is a bit more to this.
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  4. 04-25-2010, 05:15 PM #4
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    Dchappa21
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    I find most of the thermisters mounting clips break causing them to not be on the u bend... Just throw a tie wrap around them and they work fine....

    I have found 2 fail open though.
    Last edited by Dchappa21; 04-25-2010 at 05:18 PM. Reason: thermisters not transducers duh
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  5. 04-26-2010, 09:30 AM #5
    ccservicefitter
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    There always is more to the story....It is controlled by an ems system and they decided to not run some of the units to save power. It is only a problem in low ambient conditions and with first stage. The failure of the thermisters has a different error code and I have replaced a few in the past too. This is a different failure. You can watch the readings and see that the thermister is fine and of course ohm them out. Mounting I agree is of course a issue and this is not a problem. The error happens only after the unit first starts then after that does not have any problems. I am just a tech not a engineer but a transducer make so much more sense...Thanks for you comments.
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  6. 04-26-2010, 09:36 AM #6
    Dallas Duster
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    Quote Originally Posted by ccservicefitter View Post
    It is controlled by an ems system and they decided to not run some of the units to save power. It is only a problem in low ambient conditions and with first stage. So for the mean time I wired the first fan motor contactor to the first stage contactor. I like the idea of placing the thermister on the u bend of the coil. It will work just fine however a transducer make so much more sense...Thanks for you comments.
    What's the model of roof top you working on?
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  7. 04-26-2010, 09:43 AM #7
    brooklyntech
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    is carrier moving away from motor master fan control?
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  8. 04-26-2010, 10:18 AM #8
    ccservicefitter
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    I don't have the model number, it was on a Target store. Carrier has that special relationship with Target. The model is particular to Target according to Carrier, I talked to a Carrier engineer and he said he would get back to me on this. Well that was like 2 months ago.
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  9. 04-26-2010, 08:13 PM #9
    Dallas Duster
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    Quote Originally Posted by ccservicefitter View Post
    I don't have the model number, it was on a Target store. Carrier has that special relationship with Target. The model is particular to Target according to Carrier, I talked to a Carrier engineer and he said he would get back to me on this. Well that was like 2 months ago.
    Ah now that were kinda know what we are working on ? Why is the unit not economizing? Is your enthalphy switch working correctly? The HG's are pretty good unit's I bet it doesn't even have a motormaster on it . You might want to insulate the current sensor to see if that helps.
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  10. 04-26-2010, 08:30 PM #10
    y7turbo
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    So what is the exact problem you're having? You said something about an error code during low ambient conditions, What error code are you talking about?
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  11. 04-27-2010, 10:35 AM #11
    ccservicefitter
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    Good point listener. High humidity in my neck of the woods for the economizer. No motormaster on this unit.
    Turbo-high head pressure is the error, I don't remember the exact error #. I know the error # is different for a failed thermister.
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  12. 04-27-2010, 12:31 PM #12
    y7turbo
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    Quote Originally Posted by ccservicefitter View Post
    Good point listener. High humidity in my neck of the woods for the economizer. No motormaster on this unit.
    Turbo-high head pressure is the error, I don't remember the exact error #. I know the error # is different for a failed thermister.

    Take the panels off where the thermisters are. I just found 5 of them broken with no error codes on the comfort link panel at 1 retail store. They would still read temperature, and would bring on the fans but late. I think they were sensing the heat generated by the coil but they were not directly sensing the coil temperature.

    Now every unit I work on with those condenser thermisters, I take the panels off to check the sensor. You would be surprised on how many I find with broken clips and are just hanging next to the coil.

    Anyway, I dont know if that helps, but its something to look into.

    good luck.
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  13. 04-27-2010, 01:46 PM #13
    ccservicefitter
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    Turbo- I will look into it thanks for your help
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