This one has me baffled... Here's the scenario; My 2003 MCS will overheat VERY intermittantly (maybe once a month) when the air conditioning is on. Had it back to the dealer (Brecht Mini, San Diego) and they could find nothing wrong. Thermostat is OK, coolant system flushed, refilled, pressure tested. They said all was normal.

Here are the symptoms; When it overheats I've got the airconditioning on, the temp guage pegs and I pull over and stop. When I shut off the engine there is a fan running like mad but it's NOT the radiator fan. (I was under the impression that there are only two fans, the radiator and the power steering pump fan) After it sits 10 or 15 minutes I start it up and go on my way with NO overheating problems---even when I resume using the air conditioning.

I'm clueless as to what could cause this. If it was a sticky thermostat it wouldn't matter whether the air was on or not. Why is the OTHER fan running instead of the radiator fan? Can I assume it's the steering pump fan? I know of no other fan than those two...

Any ideas or anyone experience anything like this one?

Thanks in advance...

 

If its not the radiator fan, then its definitely the power steering pump fan (which I believe is on the same circuit).

 

Did you get the wiring harness upgrade for the PS fan to put it on a separate circuit? The dealer may be trying to ignore that 'cuz there's a service bulletin on it. On their dime.
-skip-

 

So is it on their dime even if you have an '02 Mini S? Far out of warranty?

 

Re; the fan upgrades; No, I am not sure if I have had the steering pump fan modification or not. I'll find out when I take it in. Anyway, my question was not so much about the fans working/not working. It's about what could possibly cause the engine to overheat intermittantly only when the airconditioning is on. Does this fan modification address this issue? Maybe one of the fans is intermittantly not doing its job perhaps? It just seems odd that it happens so rarely. You'd think it would be easy to duplicate; bumper to bumper traffic on a hot day, air on max, that should do it. But it doesn't. Then on a normal day driving along with the air on auto and set at say 72...bingo! Temp gauge pegs... go figure...

Anyway, thanks for everyone's help and suggestions. I'm calling the dealer about the fan mod.

Marty

 

Are you sure it is actually overheating? Maybe its a false reading on the gauge. Does your radiator fan ever run?

 

It could be your readiator fan has a loose connection. There are two prssure switches for the radiator fan that are part of the AC system. One is high pressure, and one is low pressure. If one of those sin't working correctly that could cause it.

My thought would be to check the plug for the radiator fan.

 

I was wondering if it was a faulty gauge. I can't remember how to get the temp gauge into digital mode. I'll have to search that here in the Forum. I used to run in that mode all the time because I originally lived in Florida and it was hot hot hot... I wonder though; would it be possible for the digital temp readout to be correct? ...and then the A/D converter screw up the analog readout? I'll be that could happen.

And yes, I do hear my radiator fan running and it appears to function normally. I wonder though... the next time it over heats I've got to jump out throw the bonnet open and see if the fan is running. Maybe it's not and the steering pump fan is trying to make up for something.

At least I've got some new stuff to try...

Thanks everyone!