Hey new here guys and first post!
So basics, I have a 2002 mini with 74k, and have always had it serviced and repaired at the dealer and never had any major or costly repairs (other than a clutch replacement), but now they say my stage 1 ac fan needs to be replaced, which between parts and labor will be a $800.00, so before i drop the big bucks i have 3 questions: What is this fan and do i need to replace it, will not replacing it cause my car to overheat, and is this the same thing as my main radiator fan.

Thanks a bunch
Chris

 

1. Radiator Cooling Fan. Stage 1 = lowered fan speed through the use of a resistor. Stage 2 = full speed with resistor bypassed. No Stage 1 is usually due to failure of the resistor, and can be fixed with a new aftermarket resistor (moderately challenging because it is not plug and play), or a complete fan replacement (easiest fix).

2. Not fixing will cause your engine to run hotter, and excessive cycling of the fan at high speed. Will it cause the car to overheat? Possibly, in extreme conditions.

3. Yes.

OEM fan is expensive (which accounts for the high dealer repair price). I replaced mine last month with a TYC fan purchased from Rock Auto for $85. Fairly straight forward replacement - plug & play. This thread helped a lot:

https://www.northamericanmotoring.co...front-end.html

Do a search, and you'll find a lot of information on low speed fan failures.

 

And these:

https://www.northamericanmotoring.co...placement.html

https://www.northamericanmotoring.co...-solution.html

 

Welcome, Chrisx! What he said. It's not an $800 job, but does require placing the car in 'service mode' aka removing the bumper and unbolting the modular front end (MFE).

 

Now I'm starting to wonder as well.

No I don't believe your engine will run hotter. Think if the fan only runs in high speed then that would force the coolant to be overcooled. Excessive cycling of the high speed won't cause your car to overheat. If you only had low speed then I could see the car overheating.

It seems to me that there are 2 fixes as these guys pointed out. The dealer will quote to replace the entire radiator fan assembly, expensive. However you can also replace the resistor which shouldn't be anywhere near as expensive nor as labor intensive.

Detroit tuned sells a relay with low speed resistor that you can wire in to resolve this same issue. I really don't see any point in replacing the fan unit when the fan is good but a resistor is bad....just replace/rewire the resistor! Here's a link:

http://www.detroittuned.com/shop/ind...picture_id=500

You could call Detroit tuned and ask them what is involved with installation of the relay/resistor--I honestly am not sure where this is wired in or what is involved as far as removal is concerned. From what I hear, replacing the radiator fan unit involves putting the front end into service mode which takes about an hour to do however can be a bit intimidating for the novice..

 

I just replaced the fan assembly on my 2005 S. It took 5 hours, but would have been done much faster if I had know what I was doing in the disassembley. Now my low speed fan comes on but the temp sensor shows -40. This all started with A/C loss. Still cooling but from only one vent. Had it diagnosed as the fan assembly, so I replaced it. I don't believe I damaged the sensor when I replaced the fan. Now, I am looking at the relay/resisstor. Does anyone have any suggestions?

 

I just went through this with my mini, around the same mileage.

Here's my odyssey: https://www.northamericanmotoring.co...n-traffic.html

TLDR: I ended up replacing the entire cooling fan assembly, my power steering fan (the failure of which is often what causes your cooling fans to stop working), and a couple fuses. Cost me a couple hundred bucks and a couple hours with a buddy.

I used the walkthrough that stevedoll wrote up but the first one that chuckee98 linked to looks good too.

 

The reason why I believe the engine will run hotter is this: according to the Bentley manual, the low speed fan kicks at 105 degrees C, then shuts off at 101 degrees C. High speed kicks in at 112 degrees C, then drops to low speed after the temp reduces by 4 degrees C (108). So if there is no low speed, then the fan won't kick in until 112 degrees. (Disclaimer: I'm not sure if the fan controller knows that the resistor is bad and turns on the (high) speed fan at 105 degrees or not. I never checked.) So will the engine run hotter? I think maybe at lower engine loads, but at higher engine loads when the high speed fan would be normally running, no.

As for the excessive cycling, my fan would cycle on-off-on-off every 10 secs or so when I had the a/c on. Once I replaced the fan, the low speed would operate properly when the a/c was on, and if the temp got hot enough, high speed would kick in with no cycling. I would think that the constant on-off cycling can't be good for the fan motor.

 

Double check your temp sensor. When I disassembled my front end to replace the fan, I forgot to reconnect the sensor when I started it up to test the fan operation. I got the -40 reading and it tripped the SES light. Once I reconnected the sensor, the reading went back to normal. The SES light cleared itself the next day.

I think I remember reading somewhere that if the temp sensor isn't reading properly, your a/c won't work because it thinks it's actually -40 outside.

 

Maybe the sensor came loose. Thanks for the reply.

 

Nope. Bad low speed resistor means no fan until 234F

 

Simplest fix as described by Blwn on post#16 here:
https://www.northamericanmotoring.co...-resistor.html

You may opt for no resistor, cooler A/C & engine.