My girlfriend has a 2009 Mini Cooper that has been great up until last night. It was 10* out and the heat was working great until she came up to a stop light. With the fan speed anywhere from medium speeds to high there is no heat when the car is not moving. Start moving again and it instantly returns. Stop and you will lose heat within 15 seconds or so.

We had many many winter nights colder than this last year and this was never an issue before. She's the type of person who likes her heat cranked so its always on the warmest temp and fastest speed so I'm sure she would have noticed this before.

Does anyone have any idea what this may be? Is this common? I suspected maybe a water pump but I'm not famililar with the workings of these cars at all and whether they're mechanical or electrical.

Thanks for any help,
Shawn

 

Check your coolant level. This is a classic sign of low coolant.

Top it up if it's low and then watch the level for a week or two to see if it drops again. You might need to add a bit more a few times if air has gotten in the system; it takes a while to work its way out sometimes.

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Had the same problem today. Added coolant and now heat is operating normal. Will watch it for a few days.

 

I just noticed the same thing in my 2007s with 29K - no heat at idle. I just checked the coolant and it was about an inch below the MIN level. I'm still kind of surprised that it could be the source of the problem because I thought the overflow tank was just that: an overflow tank - meaning that the internal water system had to be "full" if there was anything at all in the tank.

Can anyone tell me the type of coolant to buy? Knowing these cars, I'm sure you can't just use the regular green stuff (prestone).

Thanks!

 

A lot of manufacturers have gotten the coolant level (including whatever is inside the reservoir) down to almost the precise amount necessary to properly operate the engine, heat, etc. (within the MAX/MIN tolerances indicated on the reservoir). This is probably done mainly as a weight-saving measure, since every extra quart of fluid you carry around is between 1-2 pounds of weight. In other words: there ain't a lot of "wiggle room" on the coolant level...

ONLY, ONLY, ONLY (can't stress that enough) use the coolant supplied by MINI or BMW (it's dark blue -- almost black -- in color, and is same stuff in either case). NEVER, EVER, EVER use the older (green) or more recent (pinkish-orange) coolants; you'll create a lot of problems for yourself. In a pinch, you can use just distilled water to top off the coolant level; but this time of year (not sure where you are in the country, but we're getting a lot of below-freezing temperatures here), that's probably not recommended, particularly with the amount of water you'd need to add to get it back to "MIN" level (too much water would dilute the mixture to the point where you could get ice in your coolant lines -- bad news).

Your dealer might top it off for you, gratis (particularly if you're still under the Maintenance Plan). But if you get a bottle of straight BMW/MINI coolant yourself, it will generally have to be diluted with distilled water (I believe it's a 50/50 mixture ratio, but check the bottle or with a SA).