Results 1 to 9 of 9
  1. #1
    Join Date
    Apr 2005
    Location
    Virginia
    Posts
    176
    Went on a service call last week that the homeowners were complaining about the upstairs H.P. was running continuously even with the t-stat in the off position. This is a 2 system house with a 1.5 ton upstairs and a 2.5 ton downstairs. When I first got there i noticed that the installers had the 2 heat pumps backwards ( 2.5 ton H.P. on 1.5 ton air handler and vice versa). So the first thing I did was switch the units around. after getting both units up and running both units operated right like they should never getting either unit to run with t-stat in off position like homeowner had stated. Even replaced t-stat upstairs and redid low voltage on the upstairs unit thinking that there might be a short in them which would cause this unit to run all the time. They call back 3 days later saying the unit had started doing the same thing, which is know the downstair H.P. I hope and think that we can assume that the problem is within the H.P. itself. Going back tommorrow to see what I can do, Any suggestions?

  2. #2
    Sticky contactor...

  3. #3
    I think so.

  4. #4
    I think so.
    Contactor

  5. #5
    Join Date
    Mar 2005
    Posts
    6
    I would advise checking the tstat wire especially if its 20 gauge or worse. If the wire gets hot could make wires short together, or a nail might have gotten it.
    Have fun

  6. #6
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    An R-G short between the air handler and thermostat, with the thermostat set in cool mode would cause the system, including the outdoor unit, to operate indefinately.
    There is nothing more frightful than ignorance in action....Mark Twain

  7. #7
    Join Date
    Jun 2003
    Location
    Hell Hole Swamp
    Posts
    4,180
    I agree with the sticking contactor theory, if it were the Tstat wire the problem would still be with the upstairs unit

  8. #8
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    Was it frozen? If the contactor welded, unless the fan switch was set in the ON position, the system would freeze when the thermostat satisfied and the indoor blower shut off, leaving just the condenser running.
    There is nothing more frightful than ignorance in action....Mark Twain

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,929
    I think hvac pro is on the right track.

    You need to check the low voltage wiring both at the stat, and from the a/h to the outdoor unit.

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