2002 V70 XC 134,000 miles. New transmission.

When I start my car in the morning, the heater doesn't work. Or, I should say the fan doesn't blow. This has been going on for a month or so, off and on. If my car has been sitting in the sun for several hours, the heat comes on full blow. Also, I have had to add coolant. Could be unrelated but the add coolant, stop engine now message just came on again. Any ideas? It's really cold here in KC and I need more heat than just in the seats!