I just replaced the manual thermostat for my high-effeciency furnace with a programmable one, however immediately the fan starting running 24/7. I tried turning the cooling/heating switch to off but it kept running. The only way to stop it was to turn the breaker in the electrical panel off. I checked the wires and all the colours match.

In addition, with this new thermostat, the fan switches to a lower speed after the ac condensor turns off but again stays on constantly.

Is this normal?

thanks.