I tried and searched for this issue in this forum and not sure if it is the new format here or whatever, I can't seem to find posts related to my problem. I always set the inside cabin temperature to 72 degrees for both left and right sides and use AUTO mode. Started recently, if I don't have my AC turned on, the middle level vents (the ones on the dash directly blowing to our face) and the foot level vents would be blowing very warm air in AUTO mode. I made sure the center rotary stratified air temp dial (the dial between the two center vents) is on the 3 blue dots (coldest) but it is still blowing very warm air to a point that it was unbearable that I have to open all the front windows or I have to turn the AC on even on a cool fall day just to get some cooled air blowing inside the cabin. Occasionally, the right side of the vents would blow cooler air as compared to the left side blowing warm air and sometimes vice versa. Whenever I turned on the AC, all is fine and blowing chilling cold air in all vents so I assume my AC is working fine. Any clue what might be the problem here ? Is this a typical symptom when the dual heater valve going south ? I think I see our heater valve has an auxiliary water pump attached to it while other E39 models do not seem to have it, is this correct ? Are the dual valves getting stuck mor the auxiliary water pump failing ?