Is there any easy way to test the stage 1 fan to see if this is an issue on my car? 2004 R50 with 100+k miles. Thanks!

Let the engine run at idle and turn on the air conditioner. After a few minutes, the radiator fan should start to cycle on and off about once every 1-2 minutes. If the fan does turn on, it's fine. If not, the low speed resistor is probably burned out.

Even now in the winter when the ambient temp is in the 40s?

I believe it should, as long as the AC reaches a certain pressure -- see post #1127. Maybe the engine needs to be warmed up, but on my car even starting from cold engine, I only have to wait a few minutes of idle. You can just try it -- if the fan turns on, you're good. If you have an electrical meter, you can check the resistance between ground and low speed pins in the connector (video link in that post).

I did the above - turned on car and had AC running. After about 2 minutes, I believe the high speed fan came on (sounded like a jet engine) for about 5 seconds, then cut off. 30-45 seconds later, it repeated. I assume that means I don't have the low speed fan at all? Anything else I should check, or should I go ahead and plan on doing the resister swap out (which may be a bit beyond me)? Thanks for any help!

This thread has proved useful to a lot of people. In general, if you are not getting the fan to run unless the AC is on your Low Speed fan is shot. The danger comes in -- when the AC Clutch coil goes out (another common failure point) and then you get no hi speed fan on demand (happened to me). The high speed fan will not come on until 221 or 231 (can't remember).

As for swapping the resistor -- I read all the DIYs... and at the end I decided just buying a TYC fan from RockAuto for $84.92 shipped.. it comes with a lifetime warranty. The swap took about 45 minutes with me having little confidence and/or knowledge of the procedure. It was also my first time taking the front bumper off.

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


Just posting this here so the next person to encounter it -- has the DIY. Doing the resistor mod requires the same pulling the fan out.. so its basically the same amount of time...but only costs $30.

The low speed is actually pretty loud. Seems like you're fine. What you did isn't enough to kick on the high speed.

Maybe I should try it again and let the AC run for longer to see what happens? Any other test I can do to see if both the low and high speed are working on my fan unit? Still reading through all 1,000+ posts in this thread, really learning a lot. Hoping to attempt an easy solution first so I don't have to dismantle the entire front end, if possible....


2004 R50.

Sorry RkW it's really not. I've never heard my Low speed from inside the car at all. With the hood down I can barely hear my low speed fan. I have to peak in to see that it's actually spinning.

In my car, I do hear the low speed from inside. But in any case, I don't think mattymini should be concerned. The fan is turning on at the expected time for low speed. if the resistor was burned out, the fan wouldn't come on at all.

Actually, doing the resistor mod doesn't require removing anything, and costs about $10-15. REPLACING the resistor in its original location, or replacing the whole fan does require pulling the fan out.

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This is correct :thumbsup: -- replacing the resistor requires the same effort. Resistor mod is quite a bit simpler -- and I think the cost of the resistor and heat sink have come down A LOT and more readily available since this thread started.

Wouldn't it still come on high speed once the AC builds up more pressure?

Is this "resister mod" able to be done to a 2004 R50? Any link to the proper resister to obtain, and a DIY for best place to mount it? I assume you do this "downstream" from the wire connection/harness so if you later replace the entire fan unit you're still dealing with original wiring "upstream" from that connector?


Thanks again for all of the help here!


I'm only up to page 11 of this thread so far...

Hi!

This is the Resistor I Use.
N' My Low Speed Works Really Good.
Almost A Year and No One Problem
Everything Works Fine.

http://www.mouser.com/Search/m_Produ...52b%2fuQ%3d%3d

That's The Place I Install My Resistor.



Attachment 105910

Is this safe to do? If so, I'll try it this evening to verify that my low speed is shot.

Can anyone confirm for me that this...




will work? If so will order and install in the next few weeks. Looks much cheaper than other options! Confirmed last night via voltmeter that low speed is fried. Great thread!

Yes that should work.
Just make sure you screw it down hard to the body & use thermal grease to get good conduction.

Cheeers

Chris

Thanks so much Chris, and to all who helped with this thread. Have no idea how long I've even had this issue, may have had it for the entire time I've owned the car (which is now ~70k miles and 6 years). I'm going to have a mechanic buddy of mine help with the install (I've never drilled/tapped anything - no jokes please!).

They work. That's what I'm using. Mounted it to a 2" strip of aluminum stock I got from lowes.

Great, thanks. What's your 2" strip of aluminum stock attached to? I assume you have some heat transfer paste/substance between the resistor and the aluminum stock, but what about between it and the vehicle?

Thermal paste between the resistor and 2" aluminum strip. Found a bolt that fits a threaded hole on the frame. If I remember I'll post a pic later.

I just did this with my '06 MCS using the Amazon resistor. Work like a charm and sure beats the hell out of replacing a perfectly good working fan.

Attachment 106122

Here's how I have mine mounted.