Aux fan conundrum - PeachParts Mercedes-Benz Forum

Fisherman · #1 06-06-2003, 10:27 AM

Anyone ever experience this one?

After getting the AC back online I noticed that my aux fan is not engaging/running.

the car got up to 100 on the guage so I thought I'd check it out.
I opened the hood and then used the tried and true method of hitting the fan with my hand. You know that trick right?

Anyway, whenever I hit it the thing turns for a few seconds. So I kept slapping it and all of a sudden it starts to roar. Okay, I said, It just hasn't been on in a long time so that musta fixed it...

It didn't! Next time I started the car with the ac on I performed the same miraculous procedure and got it running again. My hand is a little sore now...

Now here is the conundrum. What I have found is that if I apply pressure to the outer edge of the fan hub the fan starts spinning. if I can hold a piece of metal up against it long enough (the friction makes things a little hot to hold) it seems to finally continue running on it's own. This means it is getting power I guess but what in the world is causing it to turn when I apply pressure to the hub? Could it be bad brushes?

I think someone the other day stated that they diassembled their fan and was able to replace the brushes but I can't seem to find the thread.

Anyone able to help or have thoughts on the why of the pressure on the hub thing and if it is brushes (?) as I suspect then please whoever it was that made the repair (Greg?) jump in here if you would.

Thanks

rickg · #2 06-06-2003, 10:33 AM

I think maybe my thread was the one you're thinking of. I took mine apart and replaced the front bearing. The brushes actually looked pretty good. But the front bearing was toast. Yours may be going away on you, and rubbing internally somewhere on the armature. Here's the thread:
http://www.peachparts.com/shopforum/showthread.php?threadid=61632

Fisherman · #3 06-06-2003, 11:20 AM

thanks Rick!

rickg · #4 06-06-2003, 11:40 AM

Yer welcome!
I wish I'd taken some pic's as I took it all apart and put back togather to post on that thread. Let me know if you need anymore insight. It really isn't that bad to do, but you'll need a way to get the bearing cover welded back on.

wheelguru · #5 06-06-2003, 12:00 PM

I got a couple o' spares, you could have one of mine for $5 and shipping. of course I would hook them up first to make sure they work. I had to disconnect the AC when I replaced the motor - on the new one the compressor was on the other side of the engine. Since I had only used it twice anyways since I got the car I just got rid of it.

Fisherman · #6 06-06-2003, 12:07 PM

Thanks for the offer. Let me check mine first and see if it is repairable.

Fisherman · #7 06-08-2003, 07:51 PM

A little update here...

I pulled the fan off the car and disassembled it to find that one of the brush holders is cooked! and I do mean cooked good. The brush broke apart while trying to extract it so I will take a trip to the local auto electric shop tomorrow.
That is why I could push on the fan hub and it would run though. It pushed back just far enough to connect to the brush.

I am now trying to rebuild the brush holder with a little JB Weld but it's looking more nad more like I will take wheelguru up on his generous offer...

I'll let you know in 24 hours...

rwthomas1 · #8 06-08-2003, 09:37 PM

I'm an AC idiot. Is the aux fan supposed to run with the AC on? Mine doesn't, should it? RT

Holson Adi · #9 06-08-2003, 10:30 PM

Quote:

Originally posted by rwthomas1
I'm an AC idiot. Is the aux fan supposed to run with the AC on? Mine doesn't, should it? RT

I think it runs when

the freon pressure reaches a certain level
OR
when the engine temperature reaches a certain level.

cruising through newbury st. on Friday after my shock absorber venture, the aux. fan turned on even w/o the A/C.

rickg · #10 06-08-2003, 10:31 PM

Mine only kicks in when the A/C is running, and then only once it gets hot enough. I'm not sure where the temp sensor is that determines when it's "hot enough" though.

jhal · #11 06-08-2003, 10:53 PM

The fan sensor is located on the reciever/drier of the a/c system. It is the one with the brass housing that can be replaced without losing refrigerant. It determines whether or not to turn on using conduction of heat from the high pressure line of the drier...just like a coolant temp sensor, but without actually coming in contact with the substance being monitored.

rwthomas1 · #12 06-08-2003, 11:39 PM

jhal,
How do you test it? RT

Fisherman · #13 06-09-2003, 04:27 PM

My method is turning on the A/C while it is 90 degrees out and then heading up to Mt Bachelor at a high rate of speed.
Warms up the old motor pretty fast making the hill climb.
On my 300 is I hit the 100 mark on the temp guage it had better be running...

The Warden · #14 06-09-2003, 05:24 PM

Quote:

Originally posted by wheelguru
I got a couple o' spares, you could have one of mine for $5 and shipping. of course I would hook them up first to make sure they work. I had to disconnect the AC when I replaced the motor - on the new one the compressor was on the other side of the engine. Since I had only used it twice anyways since I got the car I just got rid of it.

Do you by chance still have one of the fans available? I need one as well...I'm pretty sure that my front bearing's toast and have no idea where to find a replacement bearing by itself in this yuppified area...

rickg · #15 06-09-2003, 05:41 PM

Quote:

Originally posted by The Warden
Do you by chance still have one of the fans available? I need one as well...I'm pretty sure that my front bearing's toast and have no idea where to find a replacement bearing by itself in this yuppified area...

Bearings:
http://www.bearingsdirect.com/cgi-bin/autocart.cgi?CAT=8
Top center is of page is ESI #6001. Select "shieled" or "sealed", enter qty, and off ya go.