HVAC issue

[Heinekens]

I have a strange HVAC problem that popped up recently. The air conditioning & heating on my wife's 2006 X3 with Automatic Climate Control is kaput. The blower works as I can adjust the speed up and down okay, however the temperature adjustment doesn't seem to do anything at the moment. There is no cold air when I set the temperature low and no hot air when I set the temperature high. This problem appeared after the "Low Coolant" light appeared. I refilled with about 300 - 500 mLs of properly mixed BMW coolant and the light went away. The car did not overheat as the temperature gauge never moved from it's normal position. Other than this, the car has been running great.

I've pulled all the AC related fuses and none were shot. I've adjusted the temperature, the speed of the fan, pressed the recirculate and AC buttons all to no avail . Any ideas? Thanks.