I just bought a house and this is my first experience with using a heat pump. I have put in several hours of research and understand how it works but I need someone that has experience to give me some insight on what the problems could be.

Issue is that the AC does not always work and when it does it is not very cold.

Here is what has been done:

  • AC Company has come out and determined that the dual run capacitor on the compressor is just out side of tolerance.
  • AC Company charged the system with 2 lb of R-22
  • Replaced electrical disconnect inside at the air handler
  • Replaced the thermostat with a nest thermostat

Details of issue:

Sometimes the whole system runs fine except the compressor does not turn on but the outdoor fan does. I have then turned the system on and off and the compressor starts working and the system cools fine. I have not been able to determine a pattern. There have been a few times that I think the compressor is running but the air is not very cold then there are times that the air is very cold. The AC company has been out 2 times and has not been able to figure out what is wrong.

FYI the issue occurred before and after the install of the nest.

I plan on replacing the capacitor my self tomorrow and taking a closer look at the contacts and circuitry.

System Details:

  • Heat pump model Goodman GSH130361CB
  • Air handler Trane TWE036p130B0

If anyone has any ideas please let me know.


  • What does "...run capacitor on the compressor is just out side of tolerance" mean? If you're having intermittent problems, a failing capacitor could surly explain it.
    – Tester101
    Apr 2, 2015 at 1:24
  • According to the tech the capacitor was just outside of the 5% tolerance listed on the capacitor. We do not believe this to be the problem but will be replace today. I'm also looking into the issue being in the start assist.
    – Radar5000
    Apr 2, 2015 at 17:49
  • Capacitors are like light bulbs. Either they work or they don't. When they fail they either dead short and puff up like a toad or they open and you get an infinite reading. I doubt changing your capacitor will fix the problem if it is only slightly out of a 5% tolerance. It sounds like the compressor motor is failing. Like a starter on a car sometimes it works and sometimes it doesn't. When this happens it is your signal that it is on its way out.
    – ArchonOSX
    Nov 24, 2015 at 12:18

1 Answer 1


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If the outdoor fan comes on and the compressor does not, you need a "hard start kit" this is either a potential relay and start capacitor as in my diagram or a PTC thermistor solid state start assist device that piggy backs onto the run capacitor. This is assuming your compressor is cold to the touch and has not been starting. If your compressor has been starting and is off due to the thermal overload being open Then it is due to the capacitor being bad or refrigerant being low or the compressor is mechanically tight or electrically shorted to itself internally, this is not something a homeowner will usually be able to do unless walked through it step by step.

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