My house has a Goodman split-system heat pump with an AprilAire humidifier. The system is about 8 years old. The inside unit is in the basement. The outside unit is just outside the basement, on the north side of the house, about 20' from the inside unit.
Typically, the inside unit starts up about 10-15 seconds after the outside unit. There is a humming noise coming from the inside unit during this delay, but it goes away once the unit starts up. However, I've noticed that occasionally the inside unit won't start running. It will just sit there, making the faint humming noise. I don't know how long the system will run like this, because when I notice it happening I shut off the system, let it sit for a while and then turn it back on. I'd guesstimate that it has "run" like this a couple of times for at least 15+ minutes before I noticed.
I've only noticed this behavour in the last few months, and only seen it happen 4 or 5 times. I have no idea how often it may have happened when I haven't been home.
There are two copper pipes coming out of the inside unit (I assume they go to the outside unit). One is about the width of a pencil and is uninsulated. The other is about 1/2" in diameter and is wrapped in some kind of foam-rubber jacket. The thin pipe is run alongside the thick pipe, with either duct tape or a plastic tie every couple of feet holding them together. When the system is off, the copper lines are cool/cold. When both units are running, the lines are warm. When just the outside is running, the thinner line becomes VERY hot. It is so hot, it has melted the outside insulation of one of a low-voltage line that it is in contact with. I don't know the temperature of the thicker copper pipe when this happens.
If there is a problem, and I call in an HVAC repair-guy, is this enough info to diagnose the problem and fix it, in spite of it being so intermittent?
Over the summer, I had the opposite situation. The inside unit ran fine, but the outside unit didn't run. In that case, it was obvious there was a problem because the outside unit would not start at all. It was fixed in about 10 minutes when the HVAC guy replaced a capacitor (about the size of an 8-10 oz drink can). Does the inside unit have a similar capacitor that could be on its way to failing and causing this intermittent behaviour I'm seeing?
thanks