Heat pump inside unit doesn't always start

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
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Goodman units use this cheap piece of crap they call a blower delay relay...its nothing but a stack sequencer, and NORMALLY, there is a 5-10 second delay before the blower comes on...but chances are, you have a bad one, since we keep about 8 on each van.... There is a cap on the fan motor in the air handler, and its as big a piece of crap as the GEs they use outside.
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yes, it will likely have a similar capacitor, or the blower motor itself may be about dead
I would call the same HVAC guy back out if you were satisfied with his work and price last summer.
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also, the thinner line is supposed to be hot
but not sure about the dufus that ran a low voltage line up against a hot liquid line when the unit was installed
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margarita wrote:

Make that *warm*. The liquid line should never run over about 20F above the outdoor ambient temp, or a max of 120F in areas that push the century mark in mid-summer. This isn't even close to being hot enough to melt the t-stat wire's sheathing. On a heat pump the suction line (bigger line) can however get quite hot in heating mode, especially when the indoor blower fails to run. Normal temps of the suction line (bigger line) in heat pump mode run anywhere from about 120-170F. This is still not hot enough to melt the sheathing, but then the t-stat wire shouldn't be in direct contact with the suction line, which is supposed to be insulated. There is a possibility of the suction line melting the wire insulation if the indoor airflow becomes reduced or non-existent due to a system fault.

This is standard practice.
hvacrmedic
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exactly the reason that you should not do this

Oh I would agree with you there, a lot of bad procedures are "standard practice" among neanderthal HVAC techs. If I was in charge of the licensing, about 90% of current techs would not be able to qualify and buy refrigerant, the first thing they would have to do is pass a college level course on basic thermodynamics, so they would have a FUCKING CLUE how the damn A/C system works!
unbelievable the lack of basic knowledge of the average HVAC goon
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margarita wrote:

Your sentiment might be a bit more reasonable if perchance you understood the difference between an insulated suction line and an uninsulated liquid line. There is no problem strapping the t-stat wire to the line set. If the suction line overheats in heat pump mode then the insulation will protect the t-stat wire. The liquid line (the bare pipe) will never get hot enough to harm the wire except maybe in the event of a structural fire or the Sun going NOVA. Your personal experience seems to have translated into an irrational attitude toward techs in general.
I agree that a licensee should earn that privilege rather than having it handed-over-no-questions-asked for a fee. Some states are catching on, NATE or similar certification becoming a prerequisite to licensing. We're getting there, but it won't happen overnight--putting half the HVAC workforce out of work over a short timespan would cause one helluva crisis, not just for the industry, but for the customer as well. Some of the people in alt.hvac that you protest feel precisely the same about a good number of techs, some of which have taken up residence there. Maybe they enjoy getting berated regularly. Goes along with being stupid. But there are still plenty of techs that simply don't correspond to your statements. If you haven't met one, then you're probably just a fucking cheapskate that hires the cheapest outfit in town. If you want a bigger fish, then you have to use bigger bait.
hvacrmedic
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Since you want to go there... I bet that the insulation on teh low voltage wires melts at a higher temp than the insulation on the "suction" line...you know...the HOT one when its in heat mode on a heat pump...Gee....how come its not all melted and fucked up? I mean...even tho you think that the liquid lines hot in heat mode...
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Thanks everyone for your input. Now that I know the behavour I'm seeing is not normal, I've made an an appointment for a repairman to stop by this weekend.
Kevin
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On a heat pump, in heat mode, with temps lower than 40F, you cant bet its NOT.
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