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1990 420sel
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Discussion Starter · #1 ·
I was told that the temp sensor "in the dash" has gone bad and I'd like to replace it myself. What is the official name for this part, on benzbin all I can find is heater temp sensor. I think that this sensor is the one around the radio area. Any help is greatly appreciated.
 

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its just called a temperature sensor - in cabin. Its not in the dash its in the cabin light assembly above the rear view mirror, this is connected to a small pump fan down in the passenger foot well via a rubber pipe.
 

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1990 420sel
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Discussion Starter · #3 ·
I looked on my MB CD it looks like it may be the heater temp sensor. The dealer definitely said it was the sensor inside the dash. The only one I can find is the heater one behind the radio. Sound right?
 

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ive never seen a heater sensor behind the radio, like I said if you look at the cabin light (front) assembly youll see on the left a small square grill, this is the sensor
 

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rph74 said:
I looked on my MB CD it looks like it may be the heater temp sensor. The dealer definitely said it was the sensor inside the dash. The only one I can find is the heater one behind the radio. Sound right?
I believe that 123 chassis cars have the sensor on the dash. Your dealer may be confusing the 126 with 123.
 

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1990 420sel
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Discussion Starter · #6 ·
On my cd it is 83-135 "Removal and installation of temperature sensors for heat exchanger"

The instructions say to remove radio and ashtray to access this. The reason I had the car in was to diagnose why my compressor wouldn't turn on. I'm told the climate control unit (pushbuttons) are bad, and during testing, they found this "sensor in the dash" to be bad also.

I will first try to resolder my unit before ordering a rebuilt one.
 

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Ok, I get it. We are talking about the thermostatic switch. I replaced one of those on a 126 chassis car. I believe that you could access it by removing the driver's side dash lower panel. And yes, it is behind the climate control unit. I am not sure if I had that out while replacing the witch. The thermostat switch is wired in series with the A/C switch. If either does not work, the A/C compressor clutch will not come on.

This switch has a probe that needs to be inserted into the air box.
 

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Discussion Starter · #8 ·
Correction- I went back in and spoke with the technician, rather than the service writer and it turns out to be the 2-pole auxiliary fan switch. Glad I went back in to clarify.
 

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rph74 said:
Correction- I went back in and spoke with the technician, rather than the service writer and it turns out to be the 2-pole auxiliary fan switch. Glad I went back in to clarify.
Under the dash?:confused:
 

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Discussion Starter · #10 ·
p100 said:
Under the dash?:confused:

No, its the one under the hood. ACC temp switch. On benzbin it's listed under Auxiliary fan switch>ACC temp switch. The service writer was way off.
 
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