My 2002 MCS has disappointing heat output in the cabin, regardless of setting on the controls. I flushed the cooling system, and managed to put my hand on both the intake and output hoses to the heater core...both were hot. Is it possible that my temp selection control isn't working properly? How does that system work? I have the big factory manual if someone could give me a page reference. I thought I'd check this before pulling the heater core, and thinking 2 hot hoses meant water was flwoing through it.

I don't know how hot the air should be, but it's quite literally incapable of warming the cabin on a cold morning.

 

Perhaps not entirely obvious, but the fan must be on at least position 1 to get any kind of heating or cooling at all.
The heater core is always hot, so the air arriving in the car is regulated by the vent air flaps - perhaps that's where the problem is.
I do find the vent selector switch to be pretty vague - I can redirect air to the feet or dash or windshield but the various combinations don't seem very useful, although it deals with New England winters OK.

Do you have the manual or the automatic system?

 

Manual. The fan at high speed blows lukewarm air at best.

 

Check the heater core, sometimes they can get clogged over the years.

https://www.northamericanmotoring.co...acement-2.html

 

If you've flushed the system & you think the heater core, not just the hoses, is getting hot, then the issue is with the air flaps. ECS's post refers to a disconnected linkage.
MINI heaters are also notoriously difficult to bleed the air out of.

 

It sounds like the blend door is stuck! It is used by BMW to add the correct amount of hot and cold air and when it does not move, it will do things like you are describing.