2003 MCS with 114k. Now that it's starting to be cold, I noticed earlier in the week that the air coming out on defrost/heat was not super warm. I usually keep it set at like 66 or 68 deg F. Well last night it was super chilly and I tried to turn on the heat and I tried putting it all the way to "HI" and it was just MAYBE lukewarm air after the car had been running for 30 minutes.

My friend was telling me I'd probably have coolant all over the place in the car if it was the heater core, but I haven't seen any leaks. Although, it is constantly raining here in Oregon so maybe I'm missing something. Seems I would at least smell coolant in the car though...

Is there anything else that commonly craps out on the heater system on these cars or should I be focusing on the core?

Any help/insight is much appreciated. Thanks as always guys!

 

Im fighting the same issue with our '03 Cooper.
Luke warm at best even on high.
After searching through this site I've already bled the coolant system of air bubbles and replaced the cabin air filter.
I just took the drivers side kick panel off and the core definitely gets heat to it.
The car doesn't over heat either.
I verified the main air bypass door to the heater core moves when the heat is activated as well.
The only thing I haven't done yet is pull the core to see if its airflow is blocked.

There was mention of a heat temp sensor (thermocouple) in the air ducting that may go bad causing the system to not work all the way. However it was just a mention.

**edit**
This thread:
https://www.northamericanmotoring.co...t-not-hot.html

 

Yeah, I asked an friend who used to work at a BMW shop said that the bypass door for the heater is motorized but he hadn't seen any fail on the MINIs..

Another person said to try filling the coolant and elevating the nose of the car and running it at 3k for a bit to see if there was a air bubble caught in the heater core. It is interesting since I did replace the coolant expansion tank this summer (typical cracked tank failure on that one...) and went trhough the flush/bleed procedure but maybe I did get a bubble in the heater core.

I'll try it this weekend and report back.

 

Mini does not use long life coolant...if it has not been changed regularly it might be plugged....or the thermostat is stuck open....
Make sure the coolant is full, clean and bleed....then look deeper. So many mini's have not had the coolant changed in 2x the recommened interval of 3 years or so, it is a crime imo. It can cost some folks a headgasket.....

 

I had a similar issue with low heat, and it turns out it was the heater core. This was the thread I had
https://www.northamericanmotoring.co...-low-heat.html

the heater core, like others said is one of the lowest points in the system so all the crud ends up in there.

 

Kenshin, your thread is EXACTLY what Im encountering.
I plan on pulling to core tomorrow to check for flow/blockage.

 

I did soak it in simple green and hot water to try to break up the sediment but ended up buying a new core and gaskets (you HAVE to replace them, or use RTV sealant - it tends to leak if you try to reuse it).

I tested the airflow with a shop vac and a paper towel.

The older core would hold a paper towel in place and show a little suction, but comparing it to a new core, the shop vac suction would pretty much pull a piece of paper towel into the opening.

If I can find the pictures, I'll post it.

 

Pulled the core and flushed it out today...looked like lose leaf tobacco in it.
Flushed it out real good, re-installed it.
Same deal, although the core gets MUCH hotter now
Ordering a new core/kit monday.

 

Flush the ENTIRE cooling system....and change the thermostat!!
I bet you have tons of chunks....and one chunk could block the thermostat or cause other dammage....rust and scale in a cooling system is a bad thing.

 

I changed the coolant and tried the elevation + rev to 3k trick and it got a lot of heat back!

I was going to just try popping the core off but then I looked in the manual and it said I would need new seals when reinstalling (which I didn't have).

So, in the mean I will order a new core and seals and change that along with the thermostat (already have a new one waiting).

What do you guys use for a flush procedure? There isn't one in my Bently manual. Just a drain and refill, as far as I can tell.

 

Pro tip for those attempting for the first time:

When putting the seals in, put them in the heater core rather than on the inlet/outlet tubes when installing.

If you put them on the tubes and try to reconnect, the seals will tend to bulge and squirm around.

Putting them in the core seats them nicely without any noticeable squirm or bulge. A dental mirror comes in handy for checking the backside.

 

Well I conceded defeat and we took the MINI into the dealer today to have them figure it out.
I will post back with what was done.