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1998 E320 (W210) Silver 3.2 L V6
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Discussion Starter · #1 ·
Hey guys,

I'm in the midst of a little issue here with my 1998 E320 (non 4matic) sedan.

This past weekend, the EC light came on at the climate control console, and my AC would no longer blow cold air and the compressor was off. I checked the codes, and got a B1241 error (low refrigerant pressure). As an experiment, I cleared the code, and the AC blew cold air for about an hour before going back into EC mode again (compressor off) So, with this in mind, I called up my local indy and his initial thought on the phone was that I was indeed low on refrigerant. So, this morning, I went to the shop (Mercedeshop in Miami FL - correct spelling with 1 "S") and he hooked it up to his tank of refrigerant and had his tech read off the gauges. According to the tech, I indeed had a good load of refrigerant. However, the EC mode remained on. So, I showed him that it kicked on when I cleared the code, and he then surmised that it could be related to the cooling fans, since my car was running a little hot (100° C) and the aux cooling fans had not yet turned on. He had me rev up to 2500 RPM for a second, and still no aux fan action. Basically what happens is, those fans also keep the AC compressor cool, and when they can't cool the compressor, the compressor shuts off to self-protect. He was swamped today, but he will be taking a look at my car tomorrow first thing to check the status of the fans.

In the interests of curiosity, I came here, and searched out issues with the fans. So I found out how to check the fans (key to position 2, hold both AUTO buttons for ten seconds - thank you!) and when manually engaged, the fans successfully spin up to full speed.

So, my question is, what could be the issue here? Is this something comparatively cheap (i.e. a relay) or am I looking at something very involved? Basically, my current theory is (combining both what I read here with my mechanic's knowledge) is that the fans aren't kicking in for a certain reason, and thus the compressor for the AC cannot be cooled off, thus, it shuts off within an hour or so for safety.

Sorry if it's a little complex, but just making sure I'm covering my bases.

Thanks guys!
 

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2001 E320 - Brilliant Silver/Ash: 107,000+
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17,193 Posts
I remember reading about a fan control module but not where it is. I think there is a relay in that circuit also. Try a search and maybe some threads will pop up.
 

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W210.265/2001, W220/S500/2000, Porsche 997 C2S/2006, GMC K1500/1992
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RR the fan module and save yourself the labor hrs. Relay has nothing to do with it since you can turn it on with the testing procedures. Go to sticky for the fan module RR, this is confirmed after you paid AC check up with the dealer. Guess you already paid $119 for that. So help yourself, fix what is obvious, and if you have further problem, come over here we will help.
 

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1998 E320 (W210) Silver 3.2 L V6
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76 Posts
Discussion Starter · #4 ·
Actually the mechanic didn't charge me any money yet. I think he intends to charge me if I come back. This morning I was there for maybe 20 minutes since I already pulled the codes and told him what I thought the issue was. His part came in telling me that it was something to do with the fan and the compressor shutting off due to heat.

To be honest I'm getting better at diagnostics (thank you guys) but I have yet to do anything more than swap foglamps in terms of mechanical jobs. So, rank novice here. Would you recommend DIY on this?
 

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W210.265/2001, W220/S500/2000, Porsche 997 C2S/2006, GMC K1500/1992
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One thing i concerned you may be on a wrong track, if you can get your fan run on high speed, that means the modules is OK. The fan kick on high due to 2 issues, 1. coolant temp 2 AC on. Since you have low freon code, you may need freon unless your pressure sensor at the drier is defective. When your engine is cold, fan does not engage without AC on, use a helping hand to turn on AC, watch yourself if fan kicks on faster, if it did, nothing wrong for fan module. Read out your sensors value from 1 to 10 including 11 to 21.
 

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1998 E320 (W210) Silver 3.2 L V6
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76 Posts
Discussion Starter · #6 ·
Sensor Values =

1 - 82

2 - 80

3 - 73

4 - 75

5 - 73

6 - 147

7 - 05 (compressor off obviously)

8 - 80

9 - 27

10 - 2.2

11 - 3.4

12 - 4.3

20 - 3.2

21 - 44 alternating with 255
 

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Delete the DTC and run the sensor again with the inside on Hi or 5 bar, temp set on LO, windows open for 3 minutes.
 

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1998 E320 (W210) Silver 3.2 L V6
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Discussion Starter · #8 ·
Update -

Apparently it was the fan clutch. So yes, it had something to do with the fan, but the fan itself would not properly engage at the correct speed for a given temperature. Thus the compressor would heat up, and go into "self-protect" mode to preserve itself. My shop (Mercedeshop in North Miami) had the detailed diagnosis and work completed in about three hours total, an hour of which was the part itself being delivered.

According to the shop owner, my pre-diagnosis saved myself a fair bit of money. So, thanks Benzworld! And yes, to everyone, learn how to read the actual values and DTC codes, you can save quite a bit by "doing their job for them".
 

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Why you have B1241 code ? Is that code due to excessive 22 bar pressure instead of Low pressure ?
 

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1998 E320 (W210) Silver 3.2 L V6
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Discussion Starter · #10 ·
The B1241 code was actually due to low refrigerant. They flushed and recharged my system as part of this service. I checked with the previous owner (a friend of mine) and she never actually had the system recharged. Which is pretty good considering the age of the vehicle.
 

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1922 Ford T no OBD, no ECU, no SCN
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Per my observations the electric fans always run on low when AC is on. They turn to high when engine temperature raise.
I think the main fan clutch might be separate issue as I drive for 3 rd season with fan/clutch removed and never had codes because of it.
Keep an eye on the temperature gauge.
 

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When you removed the clutch, will the fan ever runs on high RPM ? I do not have clutch in any of my car except the 92 GMC. I assume the clutch will engaged in high temp. and moves the blades faster. I guess you have to turn off AC when you going up hill in Summer.
 

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1922 Ford T no OBD, no ECU, no SCN
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Clutch is activated by radiator high temperature. My diesel with only few years old radiator made the Grapevine Grade (7 mile incline with water tanks on the shoulders every mile) at 70 mph and with 96F outside and the engine never reached 90C. Never turned AC down.
I keep new clutch/fan for summer vacations in Las Vegas, where 140F is quite common. Still might carry it in the trunk.
 

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I guess your diesel runs with much less heat than gasoline which you keep bragging in the past was forgotten. Sorry.:thumbsup: I never have a diesel engine and almost get the Detroit on my truck. But it was cost so much that I pass the deal.
 

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1922 Ford T no OBD, no ECU, no SCN
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Diesels with about 50% thermal efficiency are engines, while gassers convert about 70% energy to heat, so they are technically heaters - the mechanical power is byproduct :D
 

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1999 E300TD: 397,000 kms.Parked for the winter. 2002 Golf TDI, 455,000kms, winter beater
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I just got my car out of winter storage, first warm day, so I put the A/C on, walked to the front, the aux cooling fan isn't working. No amount of helping them by hand convinced them to operate. The fans (well, Fan, as the other one is belt driven), worked in the test mode. They just refused to run when the A/C was turned on....which initially will run them in the lowest speed.

A little investigation, the electrical connector for the fan motor would not come apart....I ended up having to cut the connector apart. the one pin (male / female) were corroded so tightly, I needed pliers to take them apart. A thorough cleaning later, fan works again immediately when I turn the A/C on. See attached pix.

The way the fan work to the best of my knowledge is like follows -- two things make it run, high coolant temp, and A/C on.

Coolant temp is pretty self explanatory.

A/C on.....as soon as the A/C is turned on, the fans run at the lowest speed....after that, as A/C pressure builds, the fans vary in speed as commanded by the controller.

To start the fans (they always start in the lowest speed, then once turning, vary speed), the controller pulses DC volts for six seconds. If the controller does not see the fan motor turning, it shuts off the power pulses, to prevent controller overheating. Due to the corrosion on my connectors, this low pulsed voltage was not enough to start them turning, thus, fans inoperative. The high test voltage (no pulses, straight 12v), was enough to overcome the corroded connector resistance, and test the fans successfully.

Might be something to watch for, especially those of us in the rust belt. Cheaper than buying a new fan. Obviously during fan replacement, the connector would have been disturbed enough to make the new fan run, but likley, it would have been enough to make the old one run again too.....not that at that point anyone would be any the wiser.

Cheers
 

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