You could be having a mechanical issue with the compressor pump....sounds like it's bogging down the motor more than it should. Maybe the clutch on the pump is binding?

If it was me, I would take it to an auto a/c shop and have them check out the pump, and the rest of the system.

 

How would you test the rad fan with a multi meter.

 

I ordered my resistor, gonna try that first before I pull the radiator out just to change the fan. I just changed the thermostat and housing to fix a leak so I'm not too keen to dump out the coolant again. AC works great, and engine never overheats.

 

That's fine... You'll just have to fiddle around and take the time to wire it in and devise a system to securely mount it.

FYI, you don't need to dump the coolant to change the fan. Just need to disconnect upper radiator hose to allow fan to slide upwards to remove. You'll lose a cupful of coolant at most, which you dump back into the expansion tank when the new fan is installed.

 

Basic electrical knowledge ...
A burnt out resistor is an open circuit... infinite resistance ....easy to check with a wiring diagram.
I could actually see the burnt out resistor visually on mine when I REMOVED the fan...
some things are so easy to check functionality why bother going all cerebral.....

 

Yup...easy and fast to swap the fan...I would think 2x before hacking up the cars wiring....
Remember there are two different versions of the fan based on production date....and the wiring is different...one had the relays on the fan side, one on the car side...
So the how-to info must specify which version....
Just swap the fan...to do it right you should yank the fan out to rewire it anyway....

 

If you have a high milage car and your engine is running rough, spray clean your mass air flow sensor. I don't know why this is not included as part of a basic engine tune up. I have solved many rough idle/poor power problems on cars with 85k - 145k miles. It is an easy job and practically free.

I was having a stumble at low rpm on the mini I just bought. 2003 with 135k miles. Cleaned the MAF sensor and fixed it right up ; )

 

IMO it's way easier and a lot cheaper to splice two wires and install a resistor (less than $10 in parts) than swap the fan. And the stock fan comes with a resistor that will fail again sooner or later...

I "hacked up" the fan's wiring right behind the plug; the car's wiring is not touched... if I ever need to swap the fan the "hack" will end up in the bin.

 

R50/53 doesn't have a MAF sensor. You can try cleaning the MAP sensor (two in the R53), but I think they usually fail in a way that cleaning won't do much good. I've cleaned mine, didn't make any difference.

 

Some things to consider:

You have a two-speed radiator fan.
Low-speed (because of an inline resistor which knocks the 12V power down by 1/3 or so) kicks on when A/C is turned on, and/or when coolant gets "kind of" hot.
High-speed kicks on unabated (full 12V) when the coolant gets very hot.
Both of these temperatures are actual degrees, but I can't recall them off the top of my head. The actual temp degrees of the coolant is not the point.

When you turn on your A/C, the fan (low-speed cycle) comes on automatically and stays on (if the system is working properly).

If/when the engine coolant gets hot enough the fan's high-speed cycle takes over, and then drops back down to low-speed when the coolant cools down.

If the (low-speed) fan does not come on when you turn on the A/C, but you eventually hear the fan cycle on and completely off, it is very likely that the low-speed fan resistor is burned. This means you know your fan is working, but only in the high-speed cycle.

Replacing the entire fan assembly is a relatively cheap fix. But it contains the same badly-designed resistor placement, so it's only a matter of time until the resistor overheats and fails again.

Doing the external aluminum resistor fix seems to work for some people. But I've found that the principles of the wiring, relays, resistor power, heat-sink and attachment are confusing to most people.

The Dorman resistor replacement part is well-designed, but ridiculously poorly-made. The wires aren't even remotely well-attached to the terminals (they're just poorly glued on), so you have to add ring terminals to their wires, drill holes in the box and attach the wires securely with nuts and bolts. It's a PITA, but it's the best fix design, and it worked out best for me. You keep your OEM fan and wiring harness, and only replace the faulty resistor (while crimp-connecting it into the wiring at the old resistor location). Plus, you don't have to fully remove the fan housing - just move things around to where you can get to the resistor (top, passenger side).

And lastly, if turning on your A/C pulls a strong load on your belt array and slows down your engine, then your A/C compressor is the problem. And that has zero to do with the radiator fan cooling system.

 

Says the man who stated in post #24

"I've fixed the low speed resistor on mine twice now..."

Most folks that replace their original fan will not have to do it a third time.

My original fan's resistor went at 109,000 miles. $70 for a brand new fan that's installed in less than an hour isn't a tough fix in my book.

 

I bought the same green cheapo resistor (bought a 2pack) and just replaced it after 5 months with the same type. Is the larger resistor the same wattage, ohms, etc?
Thanks.

 

I agree it's not a tough fix, but replacing the resistor is still easier and cheaper. Especially if you live outside the US and can't get a brand new fan for $70.

 

The larger is the same wattage but 0.47 ohm instead of 0.33 ohm.

 

Do you have a link to the larger one?

 

Sorry about the late reply... I bought it from a local shop here in Finland, part# HSA100-0R47. Couldn't find the exact same part sold internationally, but this seems to have the same specs: http://www.digikey.com/product-detai...369-ND/2366365

 

There is a slightly rough idle that is normal with these cars from time to time. When it gets worse I add some Techron and ride around at 5,000 RPM for a tank. goes back to normal for another 6 months after that. I use Shell 93 fuel, so there is something in the concentrated Techron that cleans it out a bit more than the additives in the fuel. You could probably use seafoam instead of Techron, and maybe just the high RPMs alone for that matter...

 

I think its a glitch in the DME programming that causes the goofy rough idle thing with the R53's......not dirt in the fuel system. Sometimes mine does it a few times a week....then it goes for months without doing it, then it might start doing it a few times a day, then back to a few times a month...its total random.

 

I know what you mean. Once in a while I notice it gets rough enough to shake the car itself to the point that my passengers notice. That's when I do the fuel treatment. I don't think they are related though. might be different for others.

 

I've been logging fuel trim and other sensors using OBD Fusion, and I've not been able to see any difference in the data during the rough idle...

 

When my mini starts doing the rough idle thing....the idle AFR's go from around 15:1 up to 19:1.....then when the idle smooths back out, the AFR's go back to normal level. Something is leaning out the fuel mixture at idle....just not sure if it's the cause, or the effect......and I'm not sure what is causing it.

 

Just another thought. I have an 2003 R50, 106K miles, and was experiencing the same kind of thing, where it would almost stall. I read somewhere to clean the MAF sensor at the intake. I did and it made a huge difference!! Now it barely changes idle speed, though there's still some hint of it occasionally.

- carcaveman

 

Do you mean MAP sensor? Pretty sure minis don't have a MAF sensor

 

You're probably right. I'm still learning about these engines..

 

The AFR on mine does the same during rough idle. It's also been randomly going lean (around 17:1) when giving it some throttle from idle. Cleaning or swapping the T-MAP sensor made no difference.

Latest development is that it's giving me fault code P0130 (pre-cat lambda sensor) and also going rich when cruising at over 100km/h. Now I'm hoping that a new lambda sensor will sort all these issues...