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1982 300 CDT
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22 Posts
Discussion Starter #1
Quick question... Is the auxillary cooling fan in front of the radiator supposed to engage only when the AC is on, or when the engine reaches a certain temperature? My AC doesn't work, and the fan is not coming on at all. She seems to be running a little warmer than usual, though not "hot." Any advice is greatly appreciated!

Take Care,
Dave
 

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Premium Member
W-1-2-3 Go!
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16,161 Posts
No refrigerant, no fan, as far as I know.

As long as there is refrigerant, it should turn on once it reaches a certain temp (usually 80 deg C)
 

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1982 280E
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9 Posts
From my previous research of the electrical schematics:

There is a temperature switch mounted on the side of the cylinder head which switches the aux fan. Acc. to the Heynes manual, this should operate at 110degC. From a visual inspection of the switch on my car, it looks like it only switches on at 120degC. Without the A/C working, I have never seen the aux fan to work apart from one occasion where after a service the workshop had not filled the cooling system properly causing the engine to overheat.

Now for the A/C part. There is a temperature switch mounted on the receiver/dryer which switches on at 53degC. For the refrigerant to reach this temperature, you obviously need to have (sufficient) refrigerant in the system, and the outside temperature needs to be high enough for the condensor not to cool it down to below 53degC.

I hope this answers your question?
 

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Registered
1982 300 CDT
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22 Posts
Discussion Starter #4
Thanks, gentlemen! You answered my question perfectly. My baby is so darned reliable and predictable, I tend to get paranoid and panicy when any needle deviates a hair from what I'm accustomed to. I'm glad that you are here!

Thanks,
Dave
 
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