Results 1 to 11 of 11
  1. #1
    Join Date
    Jun 2005
    Posts
    1
    About two wks ago a new unit(carrier) 38tra r22 3 1/2 ton with a 4 ton coil was installed with new line set. Did`nt have a liquid line filter put on cause I did not know about it at the time.

    Anyway the line was buzzing at first when the installer was at my house and I said it was`nt right, then looking in his manual I think he changed the fan motor speed to a higher output to reflect the higher cfm specs,at that point it seemed that the noise went away but that was when it was colder outside.

    Now I have not used the A/C until the last week when the temps started to rise. I now hear this buzzzing noise -constant coming from the ( I believe the vapor tube, the larger diameter copper tube and a gurgle from the smaller tube when the outside compressor shuts off its cycle.

    Had service guy come out and said that is normal. I asked him if he was going to test the unit by putting on the gauges to check for the right amount of freon, load, etc. and he said he did`nt have to, he could tell by the touch? for the freon I then got pissed and he used the gauges.

    I believe the left gauge was at approx 60-65 psi,and the right gauge was at the 300 mark.

    What Can I do? / what should I do?

    Thanks for all of your help





  2. #2
    Join Date
    Mar 2004
    Location
    Ohio
    Posts
    259
    Need more info. Like the temp inside, the temp outside, etc. etc. the pressures are good to have, but without the info to compare it to, they won't tell you much. As for the gurgling when the comp shuts off, that is just the pressures equalizing, it is normal.

  3. #3
    Join Date
    Apr 2005
    Location
    Chicagoland
    Posts
    211
    Is it a heatpump?
    If so would bet on it being the reversing
    valve solenoid coil

  4. #4
    Join Date
    Sep 2003
    Posts
    1,311
    Originally posted by rscott
    Had service guy come out and said that is normal. I asked him if he was going to test the unit by putting on the gauges to check for the right amount of freon, load, etc. and he said he did`nt have to, he could tell by the touch? for the freon I then got pissed and he used the gauges.
    The good old "Beer Can" method. I'd call for a different tech to come out next time. Touch only relatively tells the temperature and not the performance.

  5. #5
    Originally posted by rtu
    Is it a heatpump?
    If so would bet on it being the reversing
    valve solenoid coil
    -----------------

    I may have had a similar problem.

    Equipment:
    Carrier 38YXA 2 ton heat pump.
    Carrier dual fuel programmable thermostat.
    Natural Gas furnace with 120V/24V control transformer rated 40VA. Distance from furnace to thermostat to heat pump approximately 45 feet. (Heat pump instruction book says the following: Use of available 24-v accessories may exceed the minimum 40-va power requirement. Determine total transformer loading and increase the transformer capacity or split the load with and accessory transformer as required.)

    Problem:
    Was outside when condenser started to emit loud buzzing sound. Both fan and Pump remained stopped.
    Ran into house to thermostat. Found indicated temperature at cooling set point level. Dropped set point temperature by 1 degree and heard the soft click that thermostat puts out when initiating action.
    Ran back outside and found both pump and fan running normally.

    Solution?
    Is it likely that the burden on the 40VA control transformer exceeded the rating sufficiently to reduce the control voltage at the heat pump at the end of the 45 feet of control wiring to such an extent that the reversing valve or contactor or both failed to operate and emitted the buzzing noise?

    P.S. replaced the 40 VA transformer with a 75VA unit the next day.

    comments would be appreciated.


  6. #6
    Join Date
    Sep 2003
    Posts
    1,311
    You did not mention any accessories. Was the control wire 18 AWG or 20 AWG? Sometimes there is too much voltage drop across the wire on longer runs with 20 AWG which could cause the problem.

  7. #7
    Join Date
    Apr 2005
    Location
    Chicagoland
    Posts
    211
    Originally posted by deme
    -----------------

    I may have had a similar problem.

    Equipment:
    Carrier 38YXA 2 ton heat pump.
    Carrier dual fuel programmable thermostat.
    Natural Gas furnace with 120V/24V control transformer rated 40VA. Distance from furnace to thermostat to heat pump approximately 45 feet. (Heat pump instruction book says the following: Use of available 24-v accessories may exceed the minimum 40-va power requirement. Determine total transformer loading and increase the transformer capacity or split the load with and accessory transformer as required.)

    Problem:
    Was outside when condenser started to emit loud buzzing sound. Both fan and Pump remained stopped.
    Ran into house to thermostat. Found indicated temperature at cooling set point level. Dropped set point temperature by 1 degree and heard the soft click that thermostat puts out when initiating action.
    Ran back outside and found both pump and fan running normally.

    Solution?
    Is it likely that the burden on the 40VA control transformer exceeded the rating sufficiently to reduce the control voltage at the heat pump at the end of the 45 feet of control wiring to such an extent that the reversing valve or contactor or both failed to operate and emitted the buzzing noise?

    P.S. replaced the 40 VA transformer with a 75VA unit the next day.

    comments would be appreciated.

    [/B]
    Most HP's when the t-stat is in cool position it energizes the RV coil constantly weather calling for cooling or not.
    If the nut for RV coil is loose could cause the humming, If clip style coil adjust till quits humming.
    With the 40va trans possibly could of caused it but I doubt it, I'd leave the 75va on there though.
    Like prev post make sure its 18awg wire, To much voltage drop on the 20awg on long runs.

    [Edited by rtu on 06-10-2005 at 06:25 AM]

  8. #8
    Thanks for the information/suggestions. will follow up and advise.

  9. #9
    Join Date
    Dec 2003
    Posts
    709
    What size lineset is it? If it is too small the velocity will cause noise like water running, I like to go bigger, but that
    isnt causing your humming noise, but may be your gurgling noise. Depending on the length I would think a 3/8" liquid and a 7/8" vapor line would be the best. You may get by with 3/4" vapor but I wouldnt on a 3.5 ton.

  10. #10
    Originally posted by sadlier
    You did not mention any accessories. Was the control wire 18 AWG or 20 AWG? Sometimes there is too much voltage drop across the wire on longer runs with 20 AWG which could cause the problem.
    Believe wire size is 20 AWG.
    38YXA manual recommends 18AWG conductors. There are spare conductors in the cable; will double up on some of them and especially on the 24V Hot and 24V COM.

    No special 24V accessories in the heat pump. 5 conductors run between thermostat, furnace and heat pump, and of course 2 additional conductors for the outside temperature thermistor.(Had to move the thermistor from the side of the HP to under the HP because it showed excessive outdoor temp indication when exposed to sun).

    Thanks for the info/advice.

  11. #11
    Originally posted by rtu
    Originally posted by deme
    -----------------

    I may have had a similar problem.

    Equipment:
    Carrier 38YXA 2 ton heat pump.
    Carrier dual fuel programmable thermostat.
    Natural Gas furnace with 120V/24V control transformer rated 40VA. Distance from furnace to thermostat to heat pump approximately 45 feet. (Heat pump instruction book says the following: Use of available 24-v accessories may exceed the minimum 40-va power requirement. Determine total transformer loading and increase the transformer capacity or split the load with and accessory transformer as required.)

    Problem:
    Was outside when condenser started to emit loud buzzing sound. Both fan and Pump remained stopped.
    Ran into house to thermostat. Found indicated temperature at cooling set point level. Dropped set point temperature by 1 degree and heard the soft click that thermostat puts out when initiating action.
    Ran back outside and found both pump and fan running normally.

    Solution?
    Is it likely that the burden on the 40VA control transformer exceeded the rating sufficiently to reduce the control voltage at the heat pump at the end of the 45 feet of control wiring to such an extent that the reversing valve or contactor or both failed to operate and emitted the buzzing noise?

    P.S. replaced the 40 VA transformer with a 75VA unit the next day.

    comments would be appreciated.
    Most HP's when the t-stat is in cool position it energizes the RV coil constantly weather calling for cooling or not.
    If the nut for RV coil is loose could cause the humming, If clip style coil adjust till quits humming.
    With the 40va trans possibly could of caused it but I doubt it, I'd leave the 75va on there though.
    Like prev post make sure its 18awg wire, To much voltage drop on the 20awg on long runs.

    [Edited by rtu on 06-10-2005 at 06:25 AM] [/B]
    Nut on RV coil is tight and coil is firmly in place.
    Will also double up on some 20AWG conductors.

    Will continue to watch operation for further troubleshooting. Problem is that on South-West coast of Canada, not much call for cooling and heating worked ok in the fall/winter!

    thanks for the help.

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