I have a 06 Cooper S with 116K miles, no mods. I'm hoping someone else can give me some ideas on how to troubleshoot my AC problem, because it's not anything I've ever encountered before. (I've had cars that needed new compressors, and such.) I searched forums to see if anyone else has had a similar issue, but have come up with nothing. I'm trying to avoid expensive diagnostics and/repairs, if I can.

For about a year now, my cooper seems to randomly switch to the heater, whether the climate control is set on auto, reg. AC or even just vent. It usually lasts a minute or two, and then switches back to whatever it was on before. I can lower the temp down 2 deg, and it will immediately switch back to cold, but if I try to turn it back up, it blows hot again. I want to note that when the AC is on, it blows nice cold air, so it doesn't seem to need re-charging or a new compressor. When it malfunctions, though, it goes immediately to HOT air, not just warm outside air. Being in south Texas, of course this is kind of annoying. Also, the temp outside doesn't seem to have an affect on the frequency - it does it whether it's 65F or 98F outside. (I usually have the climate control set between 76-80F.) Note: I don't have any problem with it switching to AC, when I use the heater during the winter.

I don't have any aftermarket accessories or parts installed, except an iPod cable. As far as I know, all parts are original. I'm wondering if it's a loose wire or maybe a switch is going bad. I don't have any trouble codes, and no indicator lights have ever come on. It seems to be happening more often, lately. When it started, it was maybe once or twice a week. Now, it's pretty much every day, sometimes several times back to back. I even did the "Ask the Expert," but he just vaguely said take it to a dealership to run diagnostics.

Any ideas or suggestions are welcome. Thanks so much!

 

silly question to begin but when's the last time you changed the cabin air filter?

if it is clogged the reduced flow could be causing problems . . .

I've never been impressed with the MINI auto-a/c and I had it in my 02 and now in my 07

On a really hot and humid day here in FL, if the car has been parked outside I've had the system feel like it kicked the heat on .... but what I think is REALLY happening is the system thinks it has cooled to your desired temp and turned the a/c off while the re-circ was also off - so it opened the vents to outside air .... which is nearly 100 degrees.

I forget if the GEN1 had this setting but on the GEN2 there is a recirc setting and an auto-recirc setting. The auto-recirc setting allows the a/c to decide when to let in outside air (there's the question of the cabin filter condition again)

My car did this to me yesterday and like you I could make it go away by bumping the temp down a notch .... but then I also turned the recirc to ON vice auto-on . . . btw I leave mine set on 68 almost all the time.

I'm gonna check my cabin filter tomorrow ... no, I'm gonna order one, cuz I know it has been well over a year.

Somedays I prefer the simplicity of the climate system in my 79 ... roll down the window / / roll up the window; open the rear vent window // close the rear vent window . . .

 

Thanks, Capt_bj. That's actually a good question. It's been just over a year since I changed my cabin air filter, too. My previous car didn't have one, so I tend to forget about it. I will order a new one, and see if it helps.

I usually turn on the recirculating button when I'm using ac, so it doesn't have to work as hard and gets colder. I'm pretty sure in my case, it's the heater, cause the air feels face-searing-hot and dry like Death Valley. Lol I imagine, being on the Gulf Coast, if it was just outside air it would be a lot more humid??

I'll let you know if the filter change helps. Thanks, again!

 

On recirculate, the fresh air door opens and shut every few minutes to ensure a fresh air supply.... Have heard numbers tossed around like 20 minutes, but seems more often based upon sound....
I typically set the temp to "Lo", and recirculate....then adjust the fan to get the temp I want...
I have seen similar behavior... Not all the time, but a few...I attributed it to maybe a programed behavior to prevent ice on the coil/expansion valve...Guess a bav-tec reader could pull fault Codes from the system ( it goes far beyond the odb2), but it all seems to work good enough...so I haven't looked further/deeper.

 

I'm skeptical that an air filter change would fix an intermittent issue like this.

This is really weird to me. There's a few aspects of the climate control that confuse me, but nothing absurd as this.

Maybe whatever determines the cabin temperature is faulty and sometimes thinks it's colder than it is, and starts to produce heat?

This seems like it would be really hard to troubleshoot without blindly replacing parts.

 

I just attempted to see if I could pull down cabin temperature with the Torque android app, but I didn't seem to get anything. I thought maybe you could observe what the car "thinks" is the temperature when it irregularly actives the heat, to confirm or eliminate my hypothesis.

 

2005 MCS same exact problem... initial trip to dealer could not isolate problem.
It just decides to pump out heat randomly - very warm, not outside air.
Then back to AC.

 

Remember....
There is a "blend door" covering the heater core....the heater core is always hot/always has coolant glowing through it....
I would suspect something is commanding the door to open....thus it suddenly warms up....
I have guessed in the past, it MIGHT be programed to prevent ice on the ac unit....if it is running hard...it is very cold, with lots of condensation....so ice can happen, especially if there is reduced airflow....

 

I have the exact same problem in my 06 MCS. I have a new cabin filter, drive belt has been changed. Hot air blows for 10 or so seconds and then back to cold. I have the same concern about the dealer just throwing parts at the problem. It can be annoying here in SoFL when the outside temp is 90. I know it's not regulating temp, because I have heard the fan shift a notch when the car cools. Sounds like one of these Mini quirks.

 

Anybody ever get to the bottom of this? It seems to be happening to the wife's 06 MCS, but only when she drives it. She thinks I think she's crazy.