Results 1 to 11 of 11
  1. #1
    Join Date
    Jul 2013
    Location
    Tracy, CA
    Posts
    4

    Confused 2nd floor temp seems higher than normal after condensor unit changed out

    I recently bought a 2 story 3400 sqft home with a Carrier Split System Air conditoner (2 zone system).
    Carrier Model# 38CKC048370 : 10 SEER, 4.0 Ton capacity ... located outside.
    Tstat#1 is in downstairs dining room/hallway.
    Tstat#2 is in upstairs mstr bedrrom.
    Plenums are located in attic.
    Tstat#1 intake (20X30) is located on second floor, middle of house in large open loft.
    Tstat#2 intake (14X20) is located in large master bedroom upstairs.
    It has the Smart Vent system to help maintain temperature between 1st and 2nd floor.
    Prior to changeout, when tstats are on I would get strong airflow from vents with cool air.

    On July 4, 2013 (hottest day this year ~105 F) the outside condenser unit started making a loud grinding sound late in the day ~4pm. The unit had been on since ~10am, statying on through the whole time since both tstats were trying to maintain setpoints (Tstat#1 = 78F, Tstat#2 = 80F). The day before I changed out both air filters with new filters.

    I have a AC Home Warranty so I made appointmet for HVAC service to come check.
    Upon checking they found the condensor unit was over amping (staying at 30 amps) and had leaks.
    Service rep turned off breaker and suggested we do not use the system as it could cause a fire.
    10 days later a new condensor was installed.

    New unit = Goodman Model# GSC130481CB : 13 SEER, 4 Ton, Split System Air Conditioner

    After one day with new unit
    1. I found the upstairs was barely able to get down to ~82F (setpoint=79F) with outside temp ~88F. Downstairs was set at 79F and was maintaining setpoint. Service company came out next day and found that refrigerant was not properly filled. Proper fill was added but problem still exists with upstairs not able to bring temp down to setpoint (79F) with max outside temp ~90F until later in evening. Service rep said if proper fill did not work then there may be a leak in attic.
    2. I also noticed the downstairs and upstairs air flow is slower than what I was used to. The higher air flow speed for each tstat kicks in at startup but goes to a slower speed shortly after.
    3. With AC not able to achieve setpoints, the condensor unit is on all the time (which leads to a large electricity bill).

    Is there a problem with how the new Goodman condensor unit is wired?
    Is the Goodman compatible with the Carrier Smart Vent system?
    With a split system does the unit require extra refrigerant?
    Shouldn't the system be able to get at least a 20 degree drop indoors compared to outdoors?

    The temperature and flow seemed to be fine prior to the changeout.
    With new unit running continuoulsy I am hesitant to use the AC system knowing I will be generating a large electrical bill.

    Advice is appreciated.
    Thank You.

  2. #2
    Join Date
    Jul 2002
    Location
    Zelienople, Pa
    Posts
    2,965
    Sounds like you have a mis-matched system if they left the old evap coil.

    Is the new condenser R-22 or R410A?
    How tall are you Private???!!!!

  3. #3
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,060
    Quote Originally Posted by Mon4475 View Post
    I recently bought a 2 story 3400 sqft home with a Carrier Split System Air conditoner (2 zone system).
    Carrier Model# 38CKC048370 : 10 SEER, 4.0 Ton capacity ... located outside.
    Tstat#1 is in downstairs dining room/hallway.
    Tstat#2 is in upstairs mstr bedrrom.
    Plenums are located in attic.
    Tstat#1 intake (20X30) is located on second floor, middle of house in large open loft.
    Tstat#2 intake (14X20) is located in large master bedroom upstairs.
    It has the Smart Vent system to help maintain temperature between 1st and 2nd floor.
    Prior to changeout, when tstats are on I would get strong airflow from vents with cool air.

    On July 4, 2013 (hottest day this year ~105 F) the outside condenser unit started making a loud grinding sound late in the day ~4pm. The unit had been on since ~10am, statying on through the whole time since both tstats were trying to maintain setpoints (Tstat#1 = 78F, Tstat#2 = 80F). The day before I changed out both air filters with new filters.

    I have a AC Home Warranty so I made appointmet for HVAC service to come check.
    Upon checking they found the condensor unit was over amping (staying at 30 amps) and had leaks.
    Service rep turned off breaker and suggested we do not use the system as it could cause a fire.
    10 days later a new condensor was installed.

    New unit = Goodman Model# GSC130481CB : 13 SEER, 4 Ton, Split System Air Conditioner

    After one day with new unit
    1. I found the upstairs was barely able to get down to ~82F (setpoint=79F) with outside temp ~88F. Downstairs was set at 79F and was maintaining setpoint. Service company came out next day and found that refrigerant was not properly filled. Proper fill was added but problem still exists with upstairs not able to bring temp down to setpoint (79F) with max outside temp ~90F until later in evening. Service rep said if proper fill did not work then there may be a leak in attic.
    2. I also noticed the downstairs and upstairs air flow is slower than what I was used to. The higher air flow speed for each tstat kicks in at startup but goes to a slower speed shortly after.
    3. With AC not able to achieve setpoints, the condensor unit is on all the time (which leads to a large electricity bill).

    Is there a problem with how the new Goodman condensor unit is wired?
    Is the Goodman compatible with the Carrier Smart Vent system?
    With a split system does the unit require extra refrigerant?
    Shouldn't the system be able to get at least a 20 degree drop indoors compared to outdoors?

    The temperature and flow seemed to be fine prior to the changeout.
    With new unit running continuoulsy I am hesitant to use the AC system knowing I will be generating a large electrical bill.

    Advice is appreciated.
    Thank You.
    Your problem is related to your "not so" smart vent system.

  4. #4
    Join Date
    Jul 2013
    Location
    Tracy, CA
    Posts
    4
    Carrier system is R-22.
    Goodman system is R-22.

    I was not there when work was done.
    My wife mentioned they did not go into the attic.
    So at this point I assume they did not change out the evap coil.
    Service receipt did not indicate the evap coil was replaced.

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,342
    Mismatches can have operational difficulties, loss of capacity. Putting the Goodman on the Carrier coil is not a good match. Typical of a home warranty company. Older Carrier coils love to leak, could be dirty. Could be lousy install that didn't evacuate the system well. Or to keep costs down and make more money, they might not have put R22 back in, could have used an alternative that doesn't get full capacity.

    Not sure what smart vent is but could be zoning. A damper not properly opening can do this.

  6. #6
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,739
    The old Carrier coil should have a TXV. It should work okay with the Goodman. Nothing has changed, other than the condenser, so I can't understand the difference in airflow issue.

    I would like to know what is a "Smart Vent". Could it be the by-pass damper? That would explain the airflow problem.

  7. #7
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,342
    I wouldn't think a coil meant for a 10 SEER builder unit will have a TXV though. Back in those days, piston most likely would be my guess. We've removed so many of those poor things for leaking. Luckily Bryant was very popular in RNC in our fast growing suburb

  8. #8
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,739
    Quote Originally Posted by BaldLoonie View Post
    I wouldn't think a coil meant for a 10 SEER builder unit will have a TXV though. Back in those days, piston most likely would be my guess. We've removed so many of those poor things for leaking. Luckily Bryant was very popular in RNC in our fast growing suburb
    I am assuming that with the zoning mentioned they would have used a TXV on the coil as recommended by the manufacture.

  9. #9
    Join Date
    Jul 2013
    Location
    Tracy, CA
    Posts
    4
    Here is an update.

    I do not have the SmartVent.

    I have a Zoned Thermal Equalizer Controller, Model ZTE2S.
    The controller is designed to work with normally open, two position, spring return, 24VAC, 2 wire motorized dampers.
    Per documentation, Spring-loaded dampers do not use polarity-sensitive motors, making the wires interchangeable.
    Wiring looks good (one damper has wiring reversed but this should not matter) , LED is flashing once per second (Normal Operation).
    All wiring to/from ZTE2S looks consistent with wiring diagram.

    One possible wiring issue is at condenser.
    Wiring diagram shows 24VAC COM (blue wire from ZTE2S) should be connected to "C" (at compressor) and COMP (yellow wire from ZTE2S) should be connected to "Y" (at compressor).
    Actual condenser has 24V (red wire from ZTE2S) connected to "C" and HEAT (white wire from ZTE2S) connected to "Y".
    Can this be causing the non-cooling problem?

    My second issue has to do with the air flow from the blower.
    Both upstairs and downstairs normally start at a high flow from registers but eventually go to a low flow.
    Is there a problem with the damper control i.e failed/weak damper motor?
    Or is this how zoned systems work?

  10. #10
    Join Date
    Jul 2013
    Location
    Tracy, CA
    Posts
    4
    Problem solved. The evap coil was dirty/plugged. Both the outdoor condenser and indoor evap coil have been replaced. AC now works much better. All wiring was verified to be correct.

    Thanks for the comments/feedback.

  11. #11
    Join Date
    Nov 2011
    Location
    St. Louis
    Posts
    3,510
    Did the warranty co. cover the replacements?

    Glad you are back into cooling! That went on way too long considering the temps out there this year.

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