2001 BMW X5 3.0 blowing cool air

[uhenry1]

Hello all,
I hope someone help me with my BMW X5 3.0 with 124,250 miles. When I turn on the heater and just cool air coming out and also try to turn the heat up the control fun indicate going down and turn it down the control fan going up. I changed the water pump about 85,xxx miles on it when the water pump broke, since then there is no problem with the heater. My guess would be thermostat and someone out there with the same problem or direct me to solve the problem. Also, when turn the defroster, it's blow cool air instead of hot air. Please help>>>>

Thanks you so much,
uhenry1