Heat Pumps and Electric Heating - Humming of outside unit

I have an Arcoaire 3 ton 12 seer w 10kw heat strips. Was able to purchase before I finished my house so it set for about 2 years. Had a fellow in the HVAC come set the unit and hook up the freon lines when it was time. It worked for about a day and then the blower fan would not come on so I snooped around the fan and noticed a gray matter on the blower housing. Took the capacitor to the place I picked up the unit and the guy sold me a new one for $3. All worked well for about a week and a half. The blower works fine coming on and off, but the outside unit has a humming sound and the compressor and fan don't come on. Freon lines are not hot. The contact kicks in and has power on both sides. The small lines all have 24 volt on them. There are no obvious signs around the capacitor like the one on the blower and I have no way to check it. Wonder what your thoughts were on the capacitor being the issue. I can remove it and have the guy at the supply house check it if you think this is the problem. Will this capacitor be about the same cost?
One other thing the maunel shows a W-1 & W-2 wire. The W-1 is connected from the thermo to the blower to the outside unit. The W-2 shown in the manuel from the thermo to the blower is not connected at all, should it be?
Thanks in advance for your help.
Scott

but the outside unit has a humming sound and the compressor and fan don't come on. Freon lines are not hot. The contact kicks in and has power on both sides. The small lines all have 24 volt on them

If the contactor pulled in and you say it has power check the wire on the compressor and all over inside the unit. If you jump R to Y does it come on out side?? Do you get inside blower if you jump R to G


ED ;)

When you check voltage on the contactor, you need to check across both terminals. The voltage should be +/- 240 volts. If you check each side to ground & get +/- 120 volts you could be getting feedback. If you have the 240 across the terminals, the cap would be a good guess. If it is a dual cap (3 sets of terminals) the cost is going to be more than separate ones. One dead give away is a swelled top on the cap.

Sounds like to me that your unit is in defrost.
In defrost power is on both sides of the contactor and all the low voltage wires are energized. R, Y, O, & W.
If that is the case then there should be a pressure difference on both refrigerant lines.
If the lines are at the same pressure then the compressor is not running and the capacitor should be checked.

Thanks for you help guys. Took the cap out and was able to notice a slight swelling. So went to the suppy house and $20 later I have a nice working system. Seemed odd that both the cap in the blower & outside condenser would be bad but hey all is good now. Again thanks.
Scott

Caps are strange critters, like most electrical components, some will last forever & some won't last anytime.