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  1. #1
    Join Date
    May 2008
    Posts
    366

    Internal OL tripping

    Carrier rooftop model 50TJ-016-520YA Runs a while and trips internal OL's. Suction 70 psi. Head 285 - 290. R22. Didn't have a thermometer up there, but suction line is getting pretty cool, not cold. All three cond fans running good. Not tripping low or hi press switches. Semi hermetic. Thanks for any ideas. It was getting late. I'll get back on it tomorrow. The first time it did it I reset system and it ran for a day. Now it is tripping within 10 - 15 minutes. It seems to be doing it after noon when it gets hot in the day ???
    td55

  2. #2
    Join Date
    Dec 2010
    Location
    Somewhere in Cali
    Posts
    183
    What is the superheat?

  3. #3
    Join Date
    Jun 2012
    Location
    Queens, New York
    Posts
    66
    Check all your wiring, contactor points, and the terminals at the compressor.

  4. #4
    Join Date
    May 2008
    Posts
    366
    Didn't have a thermometer. I'll get more data tomorrow, but the SH was high because the line temp wasn't real cold. I added a little charge. It still tripped. I will check my connections, contacts, etc. that makes a lot of sense. I should check volts and amps on the compressor also. I checked volts at the contactor - about 210 phase to phase By the way this is 3 phase
    td55

  5. #5
    Join Date
    Jun 2012
    Posts
    19
    How hot is the compressor? What is the amp draw? RLA on plate?

  6. #6
    Join Date
    Apr 2012
    Location
    winnipeg
    Posts
    1,330
    clean the condenser.....
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  7. #7
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    It should be a Carlyse O6D537TCL 0600 semi hermetic.

    270 head pressure isn't going to trip an internal ovld and neither is Suction super heat thats a little high.

    Confirm SSH, Compressor full load amps loaded, ( around 26 ) and internal over load operation.

    Sometimes those Carlyses have 2 additional overloads in the pot head. Just a series circuit through the ovld thermister in the compressor windings.

    Running at FLA with even SSH high wont trip it either.

    You really have to be starving the evap to trip those Carlyse ovlds and at 70 psi suction it diesnt sound like it.

    Yes they DO fail and I HAVE jumped them out only after confirming Im not overhwating the windings

  8. #8
    Join Date
    May 2008
    Posts
    366
    Sorry I haven't responded been a long day and I wasn't able to get to it. This business has three rooftops and they were able to make it without this unit. But I'll have to get back on it tomorrow and I will get nameplate specsamp draw, SH, and I will check contacts, connections, clean cond coils, get data from comp. I will repost tomorrow and let u know the status. Thanks for the help.. And so it is possible to jump out Ovlds I see (as last resort, of course)
    td55

  9. #9
    Join Date
    Apr 2012
    Location
    winnipeg
    Posts
    1,330
    i would not jump overloads...... yes its possible ...don't do it.... compressors not cheap these days...
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  10. #10
    Join Date
    May 2012
    Location
    southern california
    Posts
    30
    Check voltage at the compressor so you know what voltage the compressor is "seeing". If voltage is good put your amp probe on and set to record max. Let unit run and see what your meter reads when it trips. Pressures readings that you're getting shouldn't be a problem. Could be faulty overload. As previously mentioned do not bypass without knowing that you are well under max amps. This procedure will help determine this. High superheat (poor compressor cooling) could also make it trip but I don't suspect this in your case.

  11. #11
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Quote Originally Posted by carmon View Post
    i would not jump overloads...... yes its possible ...don't do it.... compressors not cheap these days...
    Sometimes......when you confirmed....that the winding's....of a compressor are not overheating.......and the overload still keeps tripping and because.......it's buried in a part of the semi-hermetic compressor ........ that's inaccessible.....your only option is to jump it.......because compressors are not cheap these days.


    I have had......the thermisters....short out the control voltage....on the unit because they.....had actually made physical contact with the........ winding's.....and since compressors aren't cheap these days......I had to jump them.

  12. #12
    Join Date
    May 2008
    Posts
    366
    Been up there all day. RLA = 62 on nameplate. All wires and connections clean. No voltage drop across contacts. 210 phase to phase at compressor. Been monitoring amps closely to see what it trips at. Oh, first thing pulled a hose up and cleaned cond coils with cleaner. Started up. Pulling 77 - 80 amps. Cut off after about 5 min. Comp only, not fans. 4 safety switches in series - hi limit, lo limit, internal OL's, and a CLO ( comp lockout) which is on a small ckt bd and that is what was opening, not the Ovlds. So I jumped them (CLO). A ckt breaker on the unit, feeding the compressor (not the disconnect) started tripping at that point. Can't find amp rating on it. Amps got higher as it got hotter - in the low to mid 80s. Won't run long enough at this point to get SH. So I started removing charge. Head pressure was 345. Suction 75 with clean coils. Bumped out all I could. Amps started dropping. Got recovery machine. Kept removing - checking amps. Took out maybe 20 lbs - didn't have scales up there. Factory charge is 19 lbs. got the amps down to 62. Head 235 suction 65. Dont know SH. Haven't checked air temps. All my equip is still on the roof. Had to take another call. It's looking good. I'll be back tomorrow to check air temps. It was running for over an hour when I left.
    Last edited by tonydykes55; 06-29-2012 at 10:49 PM.
    td55

  13. #13
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    You need to adjust the charge according to subcooling. Im guessing its TXV ?

    Qell some of those Carriers are fixed orifice. If they're cap tubes then superheat.

    At least you know now it was a legitmate issue.

    I cant imagine someine putting over 30 lbs of R22 in that machine.

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