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BenzWorld Post Whore
10 E350 4MATIC
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Discussion Starter · #1 · (Edited)
A while back, I posted an issue I'm having with slowly leaking coolant which is not fixed yet at all so I just keep adding OEM MB coolant (50/50 mixture) every...oh...4-5 months.

Last Sunday, a day after I filled the coolant, the message "Coolant Visit Workshop" came on and I noticed my temp go from 85-87 all the way to 100! The needle would reach up to 100 then it would suddenly drop back down to 85-87 and this process repeated itself quite often while driving and when idling. I noticed too that my radiator fan is not working. I turned the A/C on and the radiator fan still does not turn on.

Do you think that the coolant temp sensor has gone kaput? or is the Radiator fan bad? Is there a control module before the radiator fan and the coolant temp sensor that could be bad?
 

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ya that don't sound good check all the sensors and also see if you have valeo radiator if that is the case change it immediately. also give me the model and year so i can point you to the best replacement product in market.
 

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CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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The fan control module is built into the fan itself. Check your wiring harness for damage, and if all looks good, it's probably a bad fan module.
 

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w203 c320 avantgarde auto saloon
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Hi

My friend got ml270cdi(diesel engine) and it may be different fan supply to your car but he had exacly same problem and same message on dash

He ran code fault scanner and it came up something to do with current supply. It turned to be big fan fuse which is linked to the battery. Maybe worth to check this out?
 

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BenzWorld Post Whore
10 E350 4MATIC
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Discussion Starter · #5 ·
The fan control module is built into the fan itself. Check your wiring harness for damage, and if all looks good, it's probably a bad fan module.
So if the fan control module is bad then it sounds like I'd have to replace the whole fan :(

Does anyone have the WIS diagram of the parts and the part number handy?

I have a 2005 C320 4Matic
 

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BenzWorld Post Whore
10 E350 4MATIC
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Discussion Starter · #6 ·
ya that don't sound good check all the sensors and also see if you have valeo radiator if that is the case change it immediately. also give me the model and year so i can point you to the best replacement product in market.
Not sure I have the Valeo's and I cant check because the mechanic lives 4 miles away from me :eek:

Its a 2005 C320 4Matic
 

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BenzWorld Post Whore
10 E350 4MATIC
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Discussion Starter · #8 ·
Mechanic diagnosed the issue to be the fan. He wired the fan somehow and fan would not even turn at all.

Replaced the whole radiator fan and shroud and cost me $950 including labor. :eek: The new fan is "BROSE" brand and part #A203 500 16 93.

Thanks to all who responded.
 

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2002 C320, 1986 300E
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Thanks again, Rodney.

Since hot weather is back, I've restarted troubleshooting the aircon that failed last fall in my '02 C320. It started with a burnt out auxiliary fan. My mechanic friend replaced the fan, compressor and evaporator and charged the system to no avail. I replaced the pressure switch but haven't recharged because it won't take the R134a. I have 5.1 volts at the pressure switch plug. The mega fuses have voltage and fuses 41 & 51 are good.

I cleared the codes with SDS and ended up with B1047 & B1046 (Pressure switch short or open circuit) in the SAM control unit. I also have two air flap actuator codes in the C-ACC control unit. When I preform the diagnostic test by pushing the "defrost" and "recirc", they don't ever stop blinking. I also perform the diagnostic test by pushing "0" and "EC/Rest", but nothing is striking or I don't understand the results.

Fortunately, I have the time and convenience to figure this out. Before I erased the codes, the message: "Coolant, Visit Workshop" was displayed but went away.

I wonder if a faulty coolant temperature sensor could cause the fan or ac problem?

Thanks, Rodney
 

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A faulty coolant temperature sensor can cause the fan to run on high. It can also shut off the AC compressor. But, it sounds like you have a bad refrigerant pressure switch.
 

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2002 C320, 1986 300E
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Thanks, Rodney. Is is possible to bypass the switch? There are four wires.

I have 5.01 volts at the Blue/Red and White/Pink (or Grey/Violet - hard to tell colors) wires. Brown/Yellow is ground. No reading on the Red/White wire.

It's possible I received a bad Temp Switch when I replaced it.

Maybe the system needs primed. I remember you telling me the shade tree method of opening the high side to permit refrigerant to flow.

Appreciate the help.

Earthbit
 

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looking back at your comments, I see "replaced the fan, compressor and evaporator and charged the system to no avail." When opening the AC refrigerant system, you must also replace both the drier and expansion valve. If not, those items can prevent proper flow. The drier will absorb moisture and become clogged. The expansion valve can also stick when exposed to moisture.
 

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Thanks, Rodney, for help on this.

I actually replaced the dryer (not the evaporator) with the compressor and fan. I want to hear the fan spin before replacing more A/C components, so I'm checking for power to the fan & fan operation.

Earthbit
 

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2002 C320, 1986 300E
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I switched some relays (relay P, front SAM) and the auxiliary fan spun fairly fast with the key on. Once I started the car the fan stopped. I wonder if the coolant temperature sensor could be affecting the A/C and making the fan spin so fast?

Thanks
Earthbit
 

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It is possible that if the coolant temperature is too high, it will shut off the A/C compressor. I do see that the coolant temperature sensor is ties into the ACC system. And a high coolant temp would kick the fan into high speed. Since you had SDS, I'd run a a check on that.
 

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Thanks, Rodney,

I've been testing with SDS. A-fan is good & coolant temp is ok. I've done lots of research and with your help, I'm starting to suspect the ACC Unit.

When I lost cooling I discovered the A-fan burnt up. I replaced the A-fan (with the compressor & dryer) to no avail. I then replaced the Temp/Pressure switch.

All along, when I ran the ACC diagnostic test by pushing the recirc & defrost buttons the alternating led lights would not stop blinking.

The only codes present are B1000 on the Front-SAM and flap actuator & positioning motor codes on the ACC. The discrepancy that I discovered is B1000 reads "Compressor is short or open" from the car, but "N22/7 - Comfort A/C pushbutton control module is defective on simulation mode on SDS.

B1000 does not always appear. I plan to take the ACC out to see if wires are lose or damaged. Do you know a source for an ACC Unit N22/7?

Thx,
Earthbit
 
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