it all started as summered rolled into the deep south. My E420 A/C didnt feel as cold as last summer at idle. it just figured it was time to do an AC evac and recharge because once moving it was pretty cold. I noticed the ac would cut in and out... must be low on r134a..... right....right

did the evac and recharge.... car acted exactly the same. Time to troubleshoot. Jumped pressure switch and temperature switch.... both checked out......

At this point I realized that the electric fans would only come on "high speed". This forum has taught me that the A/C controls the "low speed" setting.... It did not ever come on low speed..... checked Low Speed relay.... bammm!!! found it - blown fuse.... now I get low speed fans almost immediately when engaging ac..... no mods to my system so something still is amiss. I checked the cabin temps and while it improved enough to be okay, it still was not as cold at idle as last year..... but then I noticed it...... my fan..... seemed to be spinning somewhat slow even when it was 97degrees out and the low speed fans where engaged. rechecked with hot engine temp... still spinning slowly.... the clutch......it was bad also.....

SIDE NOTE: with the low speed fan out, fan clutch out, 100 degree temps in houston.....THE DARN CAR STILL RUNNING AT 90C..... never ran hot - never ran high in the range... A/C cooled great when moving.. WHAT A CAR !!!

OKAY NOW THE PROBLEM..... fan clutch $450- 650 bucks..... so I purchased one that was only $150 from a web site. I asked them repeatedly to give me data on the cars it would fit - My E420 was in the list. bought it... But questioned the deeepppp discount...

during my reassembly, I was fitting the center bolt on the clutch... I was tightening the bolt, and, when it started to get really tight I noticed the clutch was still quite loose. I shrugged and figured I needed to get it at least tight before I used the torque wrench to get the required 45Nm tightening. I cranked on it a bit more and SNAP!!!!!... bolt broken.... removed clutch... bolt broken deep within bearing.... sucked.. after 5+ hours of attempts to remove a bolt buried a 1/2 inch within the socket, i gave up.... priced the bearing bracket....... $450-$650 dollars also... I salvage purchased it for $125.

replaced bearing support bracket..... started again on center bolt... got to same point...tight bolt - loose clutch.. brain says "stop something else is wrong here". I took the bolt out and grabbed the old clutch....

stuck the bolt into each one.... the new clutch allowed a full 1/2 inch further bolt protrusion...... THE CLUTCHES WHERE DIFFERENT THICKNESS - BY A 1/2 INCH...... I called the parts supplier, I told them I fubar'd a $500 bracket due to the differences in parts...... the reply " our parts are to be installed by professional repair technicians"..... or some such crap....

THE SOLUTION..... I first ordered a bolt from MB dealer.... these bolt are not normal head configuration due to tight install situation......then I cut 1/2" from the bolt.... thank you AGAIN dremel...... (put the new bolt away for possible furtue use if this doesnt work) I Installed everything.....

I was hoping that the clutch I installed performed properly over the temperature ranges..... wellllllll......... it actually over performs. maybe someone can offer an explanation

I can not get the temperature up to above 80-82c for any extended period... maybe a minute.... I drove all kids of nutty ways to see if it would go higher.... it does not.... I made my normal 350 mile trip to houston last night... 80c all the way..... gas mileage - identicle to before..... A/C needed a little freon due to cooler condenser temp causing lower a/c pressures... A/C cold at idle and all speeds...

The clutch appears to do the job and then some.... for only 150$ and a few hours of frustration and a junkyard bearing bracket... and this is texas and louisiana....can you say "HOT !!!!!!!!!!!"

 

Hmm, on a 300e I thought 90c was somewhat normal in really hot weather...

 

Yeah.... my E420 ran about 85C-88C(188F) actually...... but now it is about 80-82C(178F) with this new clutch contraption.......10 degrees cooler.... I just checked everything again.... mid day outside temp 96F with 51% humidity... car gauge around town 81C, on highway 80C.......

 

My car is usually does 80c on the highway but on city driving it jumps close to 90c when sitting at a stop light...

 

ironically, I havent heard the high speed fan since the clutch upgrade... I put the car in my garage running (exhaust pipe routed outside) to make sure it was still working after my repairs..... finally after almost 20 minutes and a really really hot garage, it kicked on....

low speed is intermitent which is okay....... high speed has yet to be triggered while driving with new clutch...

 

I haven't used my aux fan in umm? 6 years... but i don't normally turn on the A/C...

You can turn the on by holding both fan a/c buttons at the same time for 10sec to make sure they work.

 

WTF lol does that work on all W124s?

Your E420 runs about 10 cooler than man. Then again. I'm running water only in the expansion tank - perhaps thats why?

I've been considering running dual or a single big electric fan and replacing the current. Good idea or should I skip it? I want to get the car running as cool as possible.

 

Wait, that will force the AUX fan on?

 

Maybe this errant clutch is the thing to buy to get that 10 degrees..... It sure is doing it for my E420... and at $120-150 (vs the $650 sachs part). gotta be as cheap or cheaper than the electric fan and associated wiring and mounting parts.....

 

I'll look into the clutch. It's time for a radiator flush soon anyways.

Also, A friend of mine said $350-400ish installed for the electric fan setup.

 

What is the brand name of the clutch? Mine just came in a couple days ago. I figured that if I can stick my hand into the fan and stop it dead in its tracks with a 90C + temp....it needed to be replaced. Thanks for the heads up on the center bolt issue, I'll keep that fresh while I swap them out today. No more panic attacks or blasting the heater when I see the highway jammed ahead of me, fingers crossed.

 

Not sure if this applies to your 420 but the coolant temp sensor that kicks the the aux fan relay at 110C on my m103 is isolated to the fan, and therefore can be modified without altering the ECU's mixture performance(separate coolant temp sensor). So it can be "modified" using a resistor in parallel to kick the aux fan relay on at a lower temperature. Peachparts forums has some threads on this.

 

Manufacturer : ACM (Borg Warner?)
Part NO. : W0133-1597469
claims to fit 1994-95 W124 E420 (only if you shorten center bolt - and it has different temp characteristics - beneficial at present)

 

Yup, worked for me. Just hold them for 10 sec and listen.

 

Hrm. Nothing happened for me. Does that mean my fan is broken?

 

Put they key on the second position and press the buttons for 10 sec... It worked for me when it didn't work before...???

 

Damn i have been a little aprehensive to stick my hand in the fan, or are you lying and tried it with something else first lol? I know i need a fan clutch as well on 420.

I got stuck in rediculous traffic here on the cape today. Had to blast the heat (5 min. off, 5 min. on) for a good 45 minutes in 85-90 degree weather.

 

Yeah.... it may be time. Are you getting the low speed and high speed fan ouput?... if you read my write up, the lack of low speed started the whole snow ball... If these are performing, then the clutch may be it... the ACM clutch I ordered seems to do the trick beyond expectations...again, my post explains the problematic install that you can avoid......

 

Ahh very similar experiences on I-95 and last year the cape was a nightmare . The clutch is on, I had to fab a little cylindrical piece out of a bolt in order to lock the pulley into place while I loosened the 8mm allen bolt out (1986 300E M103). I was not joking about slamming my hand into the fins, they were just barely spinning with the engine at idle, no torque at all. When I started her up with the new fan clutch, well, lets say that I'm not going to even think about putting my hand near there! The fan really pushes air now, night and day difference. I will report back with before and after temps.

Note: UROPARTS brand www.uroparts.com part # 103 200 0422

 

Unfortunately, I no longer have my 300e.... part of the reason for selling was the high gauge temp.... I was 90-100C all the time during the brutal summer days down here..... I replaced the block temp switch with the modified one (a member here has his own website and sells them) and I replaced the radiator.... So the new owner, that lucky son of a gun, got a 300e that runs at about 90c now..... I was already mentally out of the car even after the repairs, so I sold it anyway...multiple nagging minor repairs needed.... I miss her though

 

That's why i'm going to part mine out...I'm just not mentally capable of fixing the car anymore..

 

Appatula, is that fan a proper and direct replacement? No bull****ting and fabricating?

 

the 300E has a more reasonable fan clutch.... getting the right part is a no-brainer.. the E420 has a $600+ dollar clutch.... cutting the bolt.. oh I mean "bull****ting ang fabricating" is not unheard of to save 70% on a part that is priced well well beyond the norm.... even for our beloved benz's this is high for that part..... besides, i have a $5-6000 dollar hydraulic shock replacement down the road on my S (well.... no problems yet, but they do wear out dont they?)..... I wont be able to cut that one down much.... so I put the clutch savings in my piggy bank..... beep! beep!....vroooooooooommmmmmmmmmm!!!!!!

 

where was that blown fuse for the low speed fan that you found? I checked my strip fuse near the strut mount last night and it was good.

 

my goodness, I apologize for being on travel for a couple of weeks. The fuse is on the actual relay itself. the relay is under the screwed down plastic cover just behind the fuse box in the engine compartment. There are threads showing pics of the actual fuse and location. Sorry again