I mean the electric fan mounted to the AC evaporator in front of the radiator. Mine doesn't seem to run at all, regardless of climate control setting, engine speed or road speed. What's wrong?

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'81 300TD turbo <<sold 12/05 to another diesel nut

Ok,, not sure on your particular car...
but it is often supposed to come on when EITHER the switch on the engine block or one of the switches on the Reciever Dryer signal it to....
So you could have a problem in both of those senders ( could happen) or the relay they operate , or the fan itself.. or the fuse or any of the wiring to any of the aformentioned parts...

What makes you think it's not working?

There is usually a bit of a delay, so check to be sure it's not running a minute or so after you turn it on.

Maybe you turn your ac on, then run o/s to see if it's working, you see it's not then you hop back in and it turns on and you don't know it.

The only thing I know for sure is that if it's not working, your compressor won't stay on as a safety precaution to prevent it from tearing up.

Someone correct me if I'm wrong.

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Enough about me, how are you doing?

"The only thing I know for sure is that if it's not working, your compressor won't stay on as a safety precaution to prevent it from tearing up."

yes, IF your car is wired correctly and your temp and pressure sensors are properly working.

Is that fan supposed to be on whenever you are running the AC?
My ACC is bypassed, and I turn my compressor on manually (bought it that way). The slime ball I bought the car from said that was an alternate cooling fan that came on at 212 degrees, or somesuch. Was that more lies?
Jimmy

I do not know if it was designed to be on ALL the time your AC is on....
However, from lots and lots of studying AC stuff ( including constructing a complete system for my Karman Ghia from three different sets of left overs ) I know for sure that the air across the condensor is the major and most important physical bottleneck in an auto ac system....
This means that some less than max efficiency can exist from circumstances ( like fins clogged in the Evaporator box )... or ever so slight undercharge, etc.... IF your system is overdesigned and working great at the AIR across the Condensor stage then it can make up the differences....
So whether or not it was supposed to work ALL the time the AC is on from the factory....
You will be in GREAT shape if you have it on all the time your AC is working... it will cause the compressor to work less... and help out all around.. particularly here in Texas....

I appreciate the info. I had a work buddy talking about wanting a Karman Ghia just last week. He grew up with a Beatle, and wants a Karman convertible now. His wife just got a brand new diesel beatle last night. 58mpg highway supposedly!
Jimmy

So, is there a simple way to wire the fan so it will always run when the AC is on? I just notice that cooling tapers off substantially whenever the car is not moving (waiting at stoplights, etc.).

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'81 300TD turbo <<sold 12/05 to another diesel nut

First off check the normal things and clean them up.... the front, rear fins on both the condensor AND the radiator.... air can't get through the first if blocked by the second...
Then be sure your fan is running when it should..... and likely it is running when you are sitting still in traffic.... but that your system just does not have the ' reserve cooling capacity" to meet the situation...
If this is the case then consider putting one of the high capacity fans in place of your current aux fan...
like the SPO or something.... check the CarlisleAutoair site (San Antonio, Texas) for the Cfm ratings.... then see if Phil at Fastlane can order you one...

The old ( and very rare )VW system was one of the best designs I have even seen. It only had a compressor in the engine compartment.... all the rest... the condensor and evaporator were housed in one box.... and used only ONE fan motor ( two squirrel cages attached , much more efficient than regular fan blades). So it was basically like a home window air conditioner mounted behind the rear seat in the Beatle or Karman Ghia....
Of course they were not the only ones which used the rear mount position... the 1957 Buick also had that.... with clear tube sticking out of the rear hat deck... and I remember ice particles landing on us sometimes from the aerial angle..... that unit was manufactured in Ft Worth I believe....sure cleans up the engine compartment....
LOoks like things are posting out of order in this thread.. happens sometimes.... I was responding to the KarmanGhia remark of course....
I did not use that system for my scratch build... having only usual under the dash units to scrounge from ... I cut a hole in the front, mounted a fan, welded and bondoed the dash and cut a hole in it, and mounted it above the gas tank .... really did not have any extra knee room.... covered the smoothed dash with leather of course.... and the first night after putting the leather on.... a cat tried to jump to the dash... and put scratch marks as it tried to hold on.... not enough space for a cat on the dash of a KG.... LOL.. I was sick....and I did not even own a cat.... I had the windows open and the car in my shop to let the contact cement smell leave during the night....

Fan always on with AC with this simple wiring modification

Works well with my w123....my AC is on most of the time..........even in winter in Australia !

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Wow, that's a clean engine compartment! Nice...

David Speed: Thanks for posting. That's exactly the solution I was looking for, but can you expliain further? So, it looks like you disconnected the factory switch in the upper right of the photo, then connected those wires to the relay? Is that a stock relay, or one that you added? Any chance you could draft up a wiring diagram, or explain which wires you connected to which terminals on the relay?

Thanks again!

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'81 300TD turbo <<sold 12/05 to another diesel nut

I added the relay........any 12V 20A SPDT Automotive type will do.................pic attached of Bosch type as an alternative to the one shown in my pic

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Detal pic of my relay and its connections

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