The symptom I'm dealing with is that the heat pump system isn't cooling as much as it should. Tested it today, was about 79°F inside and outside; system was blowing air at about 73°F.

Outdoor unit seems to start up and run fine. Air handler is pulling air pretty good. The line sets were about the same temperature when the system was running. Weird thing (I think) is that the liquid line seem to cool for a little bit when the system started up and again after I turned it off. But when it was running for a while, the line sets were about the same temperature.

The compressor doesn't sound the greatest when it starts up and shuts down, but that could be my imagination. The diagnostic LEDs on the outdoor unit indicated the system was running normally.

Any ideas?

1 Answer 1


If the lines are the same temperature, that means they're at the same pressure. Which is normal when the system is not running. Once the system starts, the pressure in one line should go up, while the other goes down.

Since the pressures in your system are basically equal, I'd say the refrigerant is low. You can verify this be connecting a set of gages to the system, or having a local HVAC technician do it for you. If the refrigerant is low, it's likely you have a leak. The HVAC technician should be able to find and repair the leak, and recharge the system.

  • Do you think a leak would likely be in the copper joints or one of the coils?
    – Joey
    Jul 11, 2014 at 19:08
  • The most common place for a leak, is right where the plumbing connects to the outdoor unit. It's not very likely to have a leak in the middle of a line, usually leaks are at joints.
    – Tester101
    Jul 11, 2014 at 22:46
  • There was a crack on the inside of a copper elbow within the outdoor unit. The HVAC technician put in a new copper section and replaced the dryer within the outdoor unit. Also, the indoor unit's expansion valve was freezing up on one side; the expansion valve was replaced. I suppose the crack in the joint was a manufacturing defect and not an installation error as the joint was within the unit.
    – Joey
    Aug 27, 2014 at 14:01

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