Update: the new valve did not resolve the warm air issue.

The only way to get tolerable (coolish) air blowing is to use the recirculate button.

With the temp setting at the lowest (60 degrees) it is still blowing warm to hot air.

What does your two heater cores read and do the valves read closed? Also ARE they closed!? Hold hand on the downstream side of the valve it should be warm not hot.

Best guess: stratification flap stuck on outside air.

OK I spent some time with the X5 late this evening. I plugged in the scan tool and took some initial readings with the car cold.

I noticed the driver side vent left of wheel and driver side (left) vent in the center stack were blowing significantly weaker power than the passenger side. Fan speed on full blast, level 9 I think it's called.

Ventilation flap said 100% on the scan tool. I did a test putting the flap to 50%, and low and behold the driver side vents power matched the passenger side vents. Odd.

Went for a test drive, air from vents was coolish at the start. I put the air to max heat for a few minutes (84) and heat got hot. Scrolled the wheel back down to max cold (60) and air cooled off but still warm.

I pulled over to idle for 5 minutes while reading data on the scan tool. Within 5 minutes the air blowing out (still set to 60) is significantly warmer, even hot.

Heat exchanger temperature, left 40.00 *C
Heat exchanger temperature, right 39.50 *C
Evaporator temperature 34.40 *C
Interior temperature 27.50 *C (81.5 *F!!)

Flap Positions
Footwell flap, right, motor position 49%
Position, stratification-flap motor 100%
Position, stratification-flap motor right 100%
Ventilation flap, motor position, left 100%
Defrosting flap, motor position 0%
Position, fresh-air recirculated-air flap 100%
Position, dynamic-pressure-flap motor 100%

Hope this helps! Also need to mention, the AC belt has been removed to diagnose a noise issue and rule out the AC compressor. So the car has no AC at the moment.

Not sure where to read the data on the valves. I didn't see it mentioned anywhere. If you describe the menu sequence to look at, I will.

If the stratification flap was stuck on outside air, wouldn't it be pulling fresh air in from outside (where it was 50*F tonight) resulting in cool air from the vents?

Forgive my ignorance, but if the flap reading is 100%, does that mean 100% open or closed.

I'll have to take some readings to compare but the heat exchanger temps of 40c mean the valves must be open. (unless there is some alternate path)

Test this by pinching the hoses shut. They have a special pliers for this but you can use a quick clamp or a couple pieces of wood and a c clamp.

If the temps drop it's the valve bit closing. This could be the controller for the valves not working.

Poke though the HVAC for real-time values of the valves and you should see them flip on/off every second or two to maintain normal temp.

It's pointless to set to minimum value just set to say 68 so the car will be heating a little bit to get the valves cycling.

I thought you were getting hot air at the same time as AC running so that changes thoughts a bit.

Let me know what those values are in your car if you get a chance in the next few days! Thanks.

Put a new AC belt on finally using the $170 BMW "stretch belt" tool. With AC off, the car blows warm air even when set to lowest temp. With AC on max, car blows barely cool air. Kind of like room temp air.

It seems like there may be a problem with the IHKA flap(s) and is allowing the heat and AC to mix. Please tell me the dashboard doesn't have to come out!!

What temps are showing on the heater cores? Evaporator?

I gave up on this DIY. I brought it into my local BMW dealership.

The AC refrigerant was very low (100 grams of 700 gram capacity). So it has a leak somewhere. Evacuate/refill was $348ish.

Still doesn't really explain to me why it is blowing hot air into the cabin even when the temp is set to 60 with AC off, and the outside ambient temp is 45 degrees F. Shouldn't it just pull in cool fresh air from outside the car?

Otherwise, you'd have to drive with AC on year round, even during winter when outside ambient temp is in the teens? Makes no sense to me.

Currently trying to communicate this with a service advisor. Will update.

The air goes through the heater cores and evaporator always so if it's getting heat it almost always is heater valve not closing.

What are the heater core temps when the issue presents?

I know that I can't keep car cool above about 60-65 ambient outside but at 50-55 usual not a problem