Heat Pumps and Electric Heating - Heat Pump doesn't come on

My older York Heat Pump quit working this weekend. We noticed no unusual sounds or activities, just realized it was cold and and when I moved the thermostat setting, it would not come on. It's like it has no power since nothing works including the fan. I have checked all breakers and outside shutoff. The heat pump (all outside unit) is at least over 7 yrs old as it was here when I bought the house. I would guess it is around 10 - 12 yrs old. I can't see any kind of reset switch on the unit. I thought it might be the thermostat since a couple of times this summer, we noticed the house was hot and found the heat strips had kicked on. I tried replacing the thermostat with no luck. Any suggestions before I call a repairman. (we live in Fayetteville, NC)

Set the "Fan auto/on" switch to on. Does anything happen??

If not you should probably call a pro since you will need special tools to go much further.

With Matt: No fan go for the transformer and from there on its get a meter and start to check out every thing.
we noticed the house was hot and found the heat strips had kicked on.

Did you find out why????? And what did you do??? A AC unit is like good for 15 years and heat pump like 7 1/2 years . But many run way over that time

ED ;)

I had a similar problem with my Armstrong 3.5 ton 3 year old unit. I found out the running capacitor was bad not allowing the energy boost needed to start the compressor. Replace the capacitor and all is well. :)