i have a heat pump with a inside furance. The unit outside is working fine but the inside blower is not always coming on. when i turn on my heat i hear the unit outside start up, but nothing inside. If i set my temp to 68 degrees everyonce inwhile the fan inside will start up and the unit runs great for about 2 days then ... nothing. Any ideas? is it just the blower inside that needs to be replaced? thanks for any advice you can give.