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  1. #1
    Join Date
    Apr 2005
    Location
    Richmond, Virginia
    Posts
    365

    Frown

    Went on a no cooling call last night for a system I installed this spring 1.5 heat pump. The owners says there is no air blowing from the indoor unit. I ask if the outdoor unit is running she says yes. I tell her to shut everything down and I'll be over within the hour.

    I get to the house and check the breakers, nothing is triped. I turn the t-stat fan switch to "on", heat and cool is "off" head to the attic to check the ahu. The fan is not running and their is ice on the coil. Makes sense so far no air flow - coil freezes. Unit is getting power so I get ready to check the run cap and I notice steam coming off the coil. The condensing unit is running in heat mode! I run down to the condensing unit to see what is going on. I pulled the O off and it sparked and I could hear the reversing valve reverse.

    I go back to the stat and shut everything down. I ohmed out the control wiring and everything came back ok.

    I go upstairs and check the run cap. It's fine.

    So I turn the unit back on set it to cool and it's running fine. I button up the AHU and go down to check the pressures.

    I get
    75 psi on the suction side w/ 15 deg SH "
    200 psi on the liquid side w/ 26 sub cooling
    indoor dry bulb 85 wet bulb 72
    outdoor ambient 80

    this is a piston metering device.

    Question, this looks like the correct charge to me. But why would the indoor fan stop running and then start again after disconnecting and reconnecting the O wire?

    This was at 9 PM last night and homeowner was going to bed so I didn't have a chance to cycle the unit.

    Sean Cantrell

  2. #2
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    Something screwy going on. With the t-stat in the "off" position there should not have been a signal to the "O" terminal or to the "Y" terminal so the outdoor unit should not have been running.

    Also, the "O" terminal is energized for cooling, not heating. The spark from the orange wire and the reversing valve switching indicate that the "O" terminal was indeed energized which means that the unit was in the cooling mode, not the heating mode.

    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  3. #3
    Join Date
    Apr 2005
    Location
    Richmond, Virginia
    Posts
    365
    There is something rotten in Goodman.

    Any ideas on where to start looking?

    Sean Cantrell

  4. #4
    Join Date
    Jan 2005
    Posts
    78
    i had a problem like that and in turned out to be a small black switch in the t-stat that i missed, look for some thing like that or call tech suppert

  5. #5
    Join Date
    Apr 2005
    Location
    Richmond, Virginia
    Posts
    365
    Tech support for Goodman?!

    The stat is a good ol' mecury stat. Nothing fancy. I didn't notice any black switches on the back of the stat when I installed it. It's a Goodman stat. Where would the switch be located?
    Sean Cantrell

  6. #6
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Lose that merc stat for starters.SH looks fine, but high SC,and low head pressure.
    If everything was always done "by the book"....the book would never change.

  7. #7
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    I'd be looking for control wiring issues. Goodman tech support; 1-888-593-9988
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  8. #8
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    OK, I see one thing going on. You have a restriction between the liquid line service valve and the condenser coil. Most likely an OEM filter/drier there that needs to be removed and piped in with copper tubing.

    Then, if there is not one already there, install a new filter/drier on the outside of the unit.

    This would have nothing to do with the control issues.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  9. #9
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,785
    The fan relay may have stuck.
    Motor may have been over heated.

    Outdoor contactor may have been stuck closed and ran without a call for cooling.


    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #10
    Join Date
    Apr 2005
    Location
    Richmond, Virginia
    Posts
    365
    Roboteq-I see what your saying about a restriction in the liquid line but wouldn't the head pressure be A LOT lower and the suction pressure lower too?

    I'm thinking like when you pump down a unit and shut the liquid line valve you see the head pressure drop?

    Went back yesterday got pretty much the same readings and unit was working fine. I sprayed the contactor with contactor cleaner just as a cautionary measure.
    Sean Cantrell

  11. #11
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    If there is a partial restriction between the service valve port and the condenser (metering device, distributor tubes, filter/drier or service valve) the system will basically need to be overcharged to push the proper amount of refrigerant through the blockage to obtain the proper superheat on the other end.

    The overcharge backs up into the condenser without showing up as higher pressure at the service port. The only way to tell the refrigerant is backing up is to check for high subcooling.

    On a fixed metered system in cooling, proper superheat with high subcooling indicates a partial blockage between the condenser coil and the service valve port.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  12. #12
    Join Date
    Jun 2005
    Posts
    40
    went on 3-service calls last week, 2 systems I just installed, one installed 10-years ago. Did some detective work talking to h.o. come to find out they put t-stat to about 60 deg. froze coil then complained they had no air flow. tell them dont turn it down so low, people usually do this when they get a new system to see if it will drop it down low.

  13. #13
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    Wayyyyy too many people also think that by turning the thermostat down lower that the system will cool faster.

    The fact that thermostats are for the most part fancy Off/on switches is sometimes a difficult concept.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


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