Our heat pump was working fine until a couple of days ago when it simply didn't come on at all. The fan doesn't come on when turned on at the thermostat, the a/c doesn't respond and after replacing both fuses at the unit still no luck. All connections appear to be solid. This is a Lennox Heat Pump about 10 years old with a motor that was replaced about 8 months ago.

Thanks in advance for any tips.

How about the breakers or fuse to the furnace, the furnace has to work and send signal to the H/P,,