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1993 300E 2.8L, 2010 ML350
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38 Posts
Discussion Starter #22
The one on the bottom of your picture is the connector for the aux fans. The one on the top is the pressure sensor. Right?
 

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Premium Member
1995 E320 Wagon
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77 Posts
The one on the bottom of your picture is the connector for the aux fans. The one on the top is the pressure sensor. Right?
You'll find out when you unplug one of them. Nothing catastrophic will happen if you unplug them. Jumper the fan sensor plugs(on body side) to each other and see if that turns on the fans. I use a small piece a reg wire.
 

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1993 300E 2.8L, 2010 ML350
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38 Posts
Discussion Starter #24
I have disconnected the fan connector plug and the fans shut off. I've plugged one of the plugs on the pressure sensors and clutch goes.
 

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Premium Member
1995 E320 Wagon
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77 Posts
That sensor plug you disconnected is for you fans since the a/c clutch was still engaged. Disconnect both connectors for that sensor and touch them together, that bypasses the sensor. At that point the fans should kick on.If your refrigerant is to low the fans won't kick on. Your refrigerant seems low, pressure should be at 30-50.
Also that port is your low side, not high side. High side pressure should be around 185 to 225, depending on ambient temp.
 

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1993 300E 2.8L, 2010 ML350
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38 Posts
Discussion Starter #28
I'll try that tomorrow after I install the new wiper assembly.
 

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Premium Member
1995 E320 Wagon
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77 Posts
I'll try that tomorrow after I install the new wiper assembly.
If when you bypass that sensor the fans kick on that could mean
A. A/c pressure to low, fill with refrigerant some more until your at around 40psi.
B. You're pressure is good and they still dont kick on, sensor is bad. You'll have to evacuate the system, replace the sensor and recharge. I would replace both sensors while you're at it.
 

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Registered
1993 300E 2.8L, 2010 ML350
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38 Posts
Discussion Starter #30
I also bought a new aux fan relay and it looks like this. Which relay does this go in, B or C - According to this there are two?
2644667
 

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Premium Member
1995 E320 Wagon
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77 Posts
Yes two relays, one for low speed and one for high speed but dont quote me,
 

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1993 300E 2.8L, 2010 ML350
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38 Posts
Discussion Starter #35
I put power from the battery to the rusty part of the resistor and the fans fired up. I suspect that is the root cause. Going to try to replace soonish. Still, added some freon and it seems to be much colder.
 

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Premium Member
1995 E320 Wagon
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77 Posts
Do you have voltage at the resistor input side? Pull the temp sensor and check for voltage at that resistor when the fans are running, If you have voltage at it then the resistor isnt your problem. It's the control side. Did you bypass the fan sensor??
 

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1993 300E 2.8L, 2010 ML350
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38 Posts
Discussion Starter #37
Yeah I have volts at the input side of the resistor.
 
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