First things first. Check your level of refrigerant. If it is low, the fan will not come on.

 

First things first. Check your level of refrigerant. If it is low, the fan will not come on.

That's not entirely correct. If the refrigerant is low, the fan won't be turned on by the refrigerant pressure switch. It should still come on courtesy of the coolant temp switch, should said coolant get hot enough. The switch you're looking for looks like this:

 

Can anybody please post an image where I can find the sensor switch for Auxiliary Fan - 1983 300SD?

 

My auxiliary cooling fan does not seem to be working in my 1983 300D. It will come on if I short out the wires on the AC reciever/drier, however even if the temp gets into the red, the fan does not come on otherwise.

Where is the temperature switch which controls the fan? Is it the sensor located on the thermostat housing?

Also, wherever that switch is, can I diagnose things by simply shorting or grounding out its leads?

Thanks.

-Jeff

On top off the A/C drier, connect the together if the aux fan still doesn't work; it's broken or the harnas in between. Check the fuses first.

 

on my '84 300D Turbo, where exactly is the location of the Thermostat Housing for the auxiliary Fan that holds the Temperature Switch? My aux fan works when I short it.
Now I'm not sure if my temp switch attached to receiver drier is the broken part but before I replace that, I'd like to know the location of the temp switch attached to the thermostat housing so I can replace it too.

 

Can anybody please post an image where I can find the sensor switch for Auxiliary Fan - 1983 300SD?

 

What is up with all these aux fan threads starting and popping back up?

 

It's A/C season, people start thinking about their aux fans...

Sort of like in Oct/Nov you start seeing lots of monovalve threads being resurrected.

 

I had the same issue this week and I create a thread about it. My conclusion was that my temp switch on the drier was kaput. So today I installed a switch on the dash to turn on the aux fan manually. I did that because for what I understood I have to remove all the refrigerante before installing a new switch and since I just put new refrigerant last week I don't feel like paying one more refill. So for now I'm using this manual switch.

 

As I stated in your thread, you can replace the Auxiliary Fan temperature switch without loosing any Freon. It does not touch any Freon, just the metal dryer housing. Don't confuse it with the compressor pressure switching the dryer. Removing that switch will cause freon loss.

 

My bad, I got confused with all the info . Got the whole new switch on the dash for nothing then

 

Mr. Uberwasser,

Thanks for sharing this exceptional iFixit link for our w123. It is giving me courage to finally face the dreadful challenge of fixing my odometer and dimmer.

 

C. Balas,

I like your idea of installing a manual fan switch somewhere under the dash. Can you please share how you did this? I believe my AC needs help to get cooler in the summer and the manual fan switch will surely help. Every morning my AC is really very cold,
but around noon the AC can no longer beat the heat.

My refrigerant is full, it's temp switch works when I short it. My dash temp needle doesn't reach red at all or hot enough for the coolant temp switch to trigger the fan ON.

I welcome any suggestions.

 

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C. Balas,

Can you please share how you did this?

It's a really simple installation. I just added tow wires connected to a switch to the existing connection fan/switch. that way the fan switch is still connected to the fan and I keep a parallel connection to a manual switch.

 

@ C. Balas:

What a clever solution! Is there noticeable difference in your cabin temperature?
I can see how useful this manual switch can be especially on summer days not HOT enough to trip the 62 C degrees temperature switch of the Receiver Drier.

Thanks for posting your very sharp and helpful photos. This'll be on my projects list.