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  1. #27
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,308
    Before digging.

    Turn on both and see if they freeze up, if not your lines are crossed, or the stat wires.

    Then turn off both, wait 5 minutes and turn one back on, see if the right outdoor unit runs. If not, the stat wires are crossed. If the correct outdoor unit runs, then go to the indoor unit and see if the large line gets cold at it, if not its the lines.


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

  2. #28
    Join Date
    Oct 2004
    Posts
    3,400
    Originally posted by dvcavall
    Jerry,
    Are you saying that in a properly running system, the suction line should not frost up?



    If the lines outside are frosting, chances are almost 100% that the indoor coils are iced over.

    Air can't flow through ice.

    It's hard to condition air that doesn't move.

    Frost on A/C = bad thing.

  3. #29
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,357
    No need to dig up linesets if there's enough exposed at the units to make the switch IF that is what turns out to be the problem.

    How's this scenario to mull over...linesets switched but control voltage was not...tstat "A" will fire up condenser "A" and tstat "B" will fire up condenser "B", but
    condenser "B" will be pumping refer through evap "A" and condenser "A" would pump refer through evap "B". Result? No airflow if indoor blower "A" has no G call but is flowing refer from condenser "B" and vice versa. End result = frosting of suction line/icing of evap on air handler with idle blower.

    Or...linesets reinstalled correctly but control voltage switched...same result. Opposite air handler gets G call, leaving matched air handler with no air flow but refer flowing through evap = frost/ice.

    Or...linesets switched AND control voltage switched...then you'd get cooling but possibly mismatched capacity if one unit was larger than the other.

    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  4. #30
    Join Date
    May 2005
    Posts
    22
    Genius I tell you...genius!!!! With a special hats off to HPJ, Beenthere and shophound.

    Did the test suggested by Beenthere, here is what happened. Both electrical boxes (where they ewit the house) and the condensers are labled (1) and (2). At this point, I can only assume that (1) is the first floor and (2) is the second floor. Let's hope that part was right.

    When I turn both on together..eureka, all is well, condensr fans turn, cold air flows, no icing just a bit of condensation on both lines...all is well.

    However, when I turn the first floor off...condenser (2) stops running and the suction line to condenser (1) which is still spinning begins to ice after 4 minutes of so!

    Based on what I think you have told me (?), that means that the stat (electrical) lines are crossed, but the coolant lines are not???? Do I have this right????

    Sounds like a much easier fix if that is it!

    When the Tech tested the system we had both running together which explains why all was well with pressures and cooling.

  5. #31
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,357
    Based on what I think you have told me (?), that means that the stat (electrical) lines are crossed, but the coolant lines are not???? Do I have this right????
    It could be either the stat wires or the linesets are crossed, but not both.

    Your technician should first switch the stat wires at the condensers, then individually test each unit, one at a time. If you get cooling from the unit you're supposed to get cooling from while the opposite unit is off and NOT calling for cooling, you're golden.

    If not, then it's a lineset issue. Tech should switch those, evacuate system, and recharge with virgin refrigerant. Liquid line drier goes in as well.

    Additionally, if it turns out to be the stat wiring, you still are faced with two systems that were not evacuated or had liquid line driers installed. This matter should be addressed.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #32
    Join Date
    Apr 2004
    Posts
    7,680
    Am I missing something? Did I read the linesets are buried?. Plan on that coming back to haunt you soon.

  7. #33
    Join Date
    May 2005
    Posts
    22
    Thank you Shophound...very much. I'll let all know what is done (or not done). I'll fax him your suggested resolution today.

  8. #34
    Join Date
    Sep 2004
    Posts
    3,157
    BeenThere :

    I have got to say that I am damn impressed. To think of all of the mistakes that someone could make on what would be a simple job( besides the issues of evacuation and the dryer) and to come up with the lines or stat wires crossed , thats good!

    BWAL12: theres one for the class to figure out

    [Edited by ct2 on 05-26-2005 at 02:19 PM]

  9. #35
    Join Date
    May 2005
    Posts
    22
    Thanks for the offer ct2. For now, I will let this contractor make good, and see what he does. Not that this guy deserves defending, but most of the work was done by a couple of young worker bees that were no doubt unlicensed and probably just learning. He actually complained to me about the fact he couldn't find competent help (after the work was done). Perhaps if he had been onsite, these mistakes might have been avoided. Who knows?

    After all is said and done, I intend to get the original contractor out, and have them purge, recharge and change the driers as suggested here just to be on the safe side, even if this guy swears up and down that de did it.

    As far as burying the lines, neither company had a problem doing so. Perhaps the milder climate in So Cal makes it less problematic? Even the original contractor had a standard rate per foot. Either one was willing to move the electrical and lines from the back of the house to the side, but it looked to be a major undertaking with high $$, stucco repair and all that would go into doing so. Extending the lines underground seemed like a common way to do it out here. Since we all know even copper corrodes under ground I had some concern, but the lines were sleeved through plastic pipe (not water tight), and the City Inspector didn't say a word. If it is a real problem in the minds of most of you, perhaps next year when I hopefully have a yard and not dirt in the back, I can go to the expense of moving the electrical and linesets to the other wall.

  10. #36
    Join Date
    Jun 2003
    Location
    South Georgia
    Posts
    17

    You can't take short cuts

    Like everyone else is telling you, the System should be properly evacuated to eliminate any and all condensables in the system. I would have added or replaced the liquid line driers on both systems (an ounce of prevention). Is there a chance that the wiring to each of the condensing units may have been switched. Therefore you will have airflow over the evap coils on the wrong air handler? That could explain the freezing of the suction line at the condensing unit. Just a thought. But you gotta do it right or you will be replaceing those condensing units long before you get your money's worth.

  11. #37
    Join Date
    Sep 2004
    Posts
    3,157
    How deep are the lines underground ? is the suction line insulated? If the refrigerant temp drops and begins to flash to liquid entering the compressor it will damage the compressor internally

  12. #38
    Join Date
    May 2005
    Posts
    22
    The trench was 16" deep. Pipes insulated above grade but not below. Freezing and the like is not a problem in So Cal. I actually covered the large conduit with heavy grade plastic sheeting and plugged the ends to slow down any migration of dirt into it before covering it back up. The conduit has weep holes to let water drain out.

  13. #39
    Join Date
    May 2005
    Posts
    22
    P.S. Wish I had known about this forum before I started looking for contractors!

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