I was on my way to the airport to pick up my wife and daughter yesterday. Just as I was
entering the parking ramp and had to wait for a gentleman exiting a stall, I noticed it
was really quiet...No A/C fan noise, No cold air...I parked it and ran into the terminal.
Upon returning I verified that under no circumstances was the fan working. As we left the airport and got up to highway speeds
I did notice cool air being pushed thru the vents, but still no fan. We arrived home and I was distracted for a few hours. I checked the fuses- all ok. I started the car and pulled the car into the garage around 10pm and the fan worked fine !!!! Spooky !
Last week I had my engine wire harness replaced. There was heat damage and it was causing an intermittent shorting. Car sounded like it was missing on two occasions.
Has Anyone seen this type of behavior?


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Bryan Harter
92 500E Smoke Silver

Bryan,

Assuming that the V8 has a similar system as the rest which monitors for belt slippage, this may be the problem. The symptoms you describe match up perfectly with a slipping belt.

Is the belly pan still under the engine?

Did you go through a water puddle?

I went through something like this several weeks back, it cured itself and all was well.

Good luck,

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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

The belt was just replaced a week ago, so that may be the best place to start. The pan is still intact and the weather was dry.
It was a long (45 minute) ride home in 98 degree heat !

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Bryan Harter
92 500E Smoke Silver

I worked fine this morning and seemed to be fine tonite as I drove to meet a friend for dinner. After 10 miles I noticed the fan had stopped again....Fuse seems ok...
Must be something that is loose or sensitive
to heat.
I hate these kinds of problems....

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Bryan Harter
92 500E Smoke Silver

If the belt slips: turn the engine off and turn it back on again, the a/c will work everytime.

If the ignition switch is bad: repeat the above test and the a/c may not be on everytime. But if you turn the ignition key left/right a little while the engine is running, you may get the a/c back on again.

I assume you check all the related fuses. Visual check of the fuses is not able to find hair line cracks or corroded contacts. You really need a test lamp or a volt meter.

David

David,

Thanks for the suggestions. It seems to be very intermittent. Turning the car off/on does not restart. The fan seems to work when I first start the car in the morning. The fan ran for about 10 minutes and stopped this morning. Then it will not come on again after sitting for many hours. I will bet that it starts when the car is cold tomorrow ! The compressor seems to be working, the vents are cold. At highway speeds the airflow is pretty cold. I have to drop the windows if I am forced to stop at a stoplight.
I checked the large blower motor fuse and it seems fine. I guess I will have to tear the dash apart to check the voltage at the fan
and the Climate Control fan switch/buttons.
This should be interesting...
Thanks again.

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Bryan Harter
92 500E Smoke Silver

Bryan,

When I experience problems after working on a particular area, more often than not I find the problem to be related.

Since you had the belt changed just before this started, There's a very good chance that this is where the problem is. I have no experience with these V8's, but I'll bet that there is a belt tensioner that has to be set according to a scale when the belt is replaced. If this was not done correctly, this is most likely where you will find your problem.

Best of luck and keep cool,

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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

If you are talking about the interior fan, there is a fuse outside the fusebox for it. It is a 30A blade type fuse...

Also, when the belt is replaced on a 500E, you have to be really careful to check the tensioner.

------------------
Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I had the same problem; it was the tebsioner.

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Best regards, Michael
'92 500E
'88 300TE

I had the exact same problem with a 300TE and it was the ignition switch. If there is power up through the 30A fuse, the switch is highly suspect.

I just dropped the car at the MB service center. The Fan worked for all of 5 minutes
today then nothing... I did check the external fuse, it was OK. The belt tension makes sense.
Thanks for the feedback.

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Bryan Harter
92 500E Smoke Silver

Bryan,

Are you still having this problem reoccur? I experienced the A/C quiting all of a sudden today and the fuses test OK with a Ohmmeter.

Nothing mechanical on the car has been disturbed for months.

Also, could someone please explain how a belt tensioner has anything to do with the ventalation fan from functioning, all other electrical accessories are functioning?

Thanks

How could it be a fuse if the fan works now and then? if the fuse blew it would not work at all right? Is there some sort of relay module that controls the fan? maybe its bad. I once had a bad power window motor in a 280 Z a few years back, it would roll up a bit then stop. if I waited it would do the same. it turned out the motor was so worn out of tolerances that it was triping a "breaker" type of device that would reset itself. just some thoughts...

As far as I know the tensioner on the newer V8s cannot be adjusted. They are spring loaded. Even if your belt slips, it wouldn't cut out the blower only the compressor. In other words your blower would blow hot air until the car is restarted or after a few minutes it would restart itself assuming that the engine speed and compressor speed sensor correspond (no slippage).
You either have a bad blower or some kind of bad contact.

Vinamg

Could the blower switch be a resistor switch?

I know a number of cars have resistor switches and when the resistor goes south the blower may only work on one setting, if it works at all. I'm not sure which Mercedes models use the resistor switches though.