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condensing unit breaker keeps tripping

will a larger horsepower condenser fan get rid of more heat. for instance if I went from 1/3 to 1/2 horsepower eventhough the fan speed is the same. I'm working on a 5 ton airconditioner. on a warm day it could run for a half hour or so but then the pressure and amperage slowly creep up then quickly moves up and trips the 40 amp breaker. when I start the unit the pressure and temperature seem ok (60# and 275# for r22). on days that aren't very warm it doesn't give me a problem. condenser looks clean. I don't know how to check for non condensibles in the system other than changing the freon and see what happpens. could a larger horsepower condenser fan help? and how do you check and get rid of non condensibles?

Comments

  • don_185
    don_185 Member Posts: 312
    I've seen

    the problem you're having often.Its that sparky went with the min on the breaker and wire size instead of going with the max.



  • jim lockard
    jim lockard Member Posts: 1,059
    What is your pipe temp

    > will a larger horsepower condenser fan get rid of

    > more heat. for instance if I went from 1/3 to 1/2

    > horsepower eventhough the fan speed is the same.

    > I'm working on a 5 ton airconditioner. on a warm

    > day it could run for a half hour or so but then

    > the pressure and amperage slowly creep up then

    > quickly moves up and trips the 40 amp breaker.

    > when I start the unit the pressure and

    > temperature seem ok (60# and 275# for r22). on

    > days that aren't very warm it doesn't give me a

    > problem. condenser looks clean. I don't know how

    > to check for non condensibles in the system other

    > than changing the freon and see what happpens.

    > could a larger horsepower condenser fan help? and

    > how do you check and get rid of non condensibles?



    Need mor info to get the full picture.
  • Techman
    Techman Member Posts: 2,144
    Breaker's

    Hi dennis!What size wire?Is the breaker in an enclose warm garage or room? Is the breaker a HACR type ? Do you have low voltage to begin with?A 275psig head should be equal to about a 90* day , what is the outdoor air temp? A 60psig suction would indicate an almost satisfied room temp,what is it?Good Luck!Let us know!
  • Techman
    Techman Member Posts: 2,144
    Cond fan H.P.

    It's me again! RPM is IT!!!!,not oversizing the H.P. Is the 1/3 hp motor the proper size?
  • Empire_2
    Empire_2 Member Posts: 2,343
    More Details

    Unit Name Mod Ser, Current Voltage, and anything more you can give would be nice. Try replacing your run cap, But I think Don has a point. How old is this thing?

    Mike T.
  • Wayne_22
    Wayne_22 Member Posts: 2
    condenser coils

    I would look at the condenser coils again. If this is a multiple row coil. the coil needs to be split prior to cleaning. I have often seen the face of the coils cleaned by other techs only to leave a large amount of debris in the coils. The coils appear clean and are not. Washing from both directions is required.

    Check the ambient air temp and the refrigerant pressure converted to temperature, subtract the ambient air temp from the converted pressure temp to determine the temperature difference, high efficency equipment my be as low as 20 degrees, standard efficency and refrigeration equipment 30 to 35 degrees. If the difference is more, the coils are dirty!

    Cleaning the coils will do more to solve the problem than a larger fan motor or more rpm.

    Wayne
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    Checking for Non-condensables

    Although I don't think this is your problem, here is how to check your system for non-cndensables.

    Turn the system off and allow it to "rest" for at least 15 minutes. With your gauges on the system, determine the static pressure in the system. Take an ambient temperature reading. Compare this pressure and temperature to the pressure/temperature chart for the refrigerant you are working on. The pressure on the chart should be the same as the pressure in the system at the specific ambient temperature.
  • Darin(in Michigan)_3
    Darin(in Michigan)_3 Member Posts: 28
    Overcharge?

    I was on a system today that was blowing a 15 amp breaker. It was rated at 20 amps. Changed the fuse but it was running much larger amperage than it should have. That and the 450# head pressure and 110 # suction pressure. 275# head seems a little high to me unless it is one of the old Chrysler Air Temps or the old Slope front luxaire. Models and seriels would help. Also, the tonage of the furnace drive would help. Is the fan going the right direction?
  • CJ_5
    CJ_5 Member Posts: 1


    Those pressures look like a 410A A/C?
  • RJ_4
    RJ_4 Member Posts: 484
    ampacity

    I agree with others on dirty condenser coil. Check ampacity rating on unit. It should be listed on name tag. Most 5 ton units have an ampacity rating of 30 amps or slightly above. If your ampacity is in this range, you need to increase the disonnect to 50 amps, the breaker to 50 amps and install 40 amp FRN fuses. Your wire size should be #8. Additionally, on the electrical side, check for any loose wire connections and check compressor and fan contactors for burnt or pitted contacts.
    On the refrig. side, check your subcooling or look at the charge chart inside the unit cover. You may have an overcharge.
    If in doubt, reclaim and weigh in new charge. All equip. without a receiver is a critically charged system.
    RJ
This discussion has been closed.