Crappier... er... Carrier Unit has blown 2 fuses in two days on heat setting. Fuse is in main blower housing. Is this a short? Any ideas?

Thanks,
Frustrated and Freezing...

If capable, remove control wire from the heat contactor, contactor coil windings may be shorted.
Or
Thermostat control wire may be barely shorting.

If this is a heat pump system, try the emergency mode short-term. If the problem doesn't re-surface, focus your attention on finding a shorted control circuit or low-voltage component at the outdoor unit (as previously suggested).