1986 4000cs AC

[Brett Dikeman]

At 12:30 AM +0000 6/20/04, Keith Davidson wrote:

>I am in Las vegas and use my car for my job as a courier. The real 
>serious heat has yet to show up so I am working on keeping the car 
>cool as well as myself once it does. I drive anywhere between 
>120-150 miles a day. Most of it freeway miles.
>A few questions
>1 ) My radiator fan is getting twitchy on me. I get a replacement on 
>monday. Should I install a switch to keep the fan on when I am 
>driving all the time ? Or let the rad. fan switch do it`s job ?

Leave it with the switch- running too cold will increase cylinder 
wear and decrease mileage.

When you have the replacement installed, consider installing a 
fuseable link.  It was added to cars after 1989 or so, to avoid 
harness/battery meltdown in the event of fan failure.  The links are 
available in wire form or you can get the parts installed into the 
100/200's.

>2 ) If not enough air is pulled through with a  'stock fan' is there 
>a more efficient replacement fan to use ? This also helps cool the 
>AC for me ,correct ?

At highway speeds, airflow shouldn't be an issue; I think airflow is 
much greater than the fan can manage anyway.  You can have both the 
AC and main radiators cleaned out of any bugs/dirt etc, but they tend 
to stay fairly clean since they're set so far back in the early cars, 
a big benefit to the design.

The only upgrades I've heard of being done with the fan is switching 
to the later blades on 100/200's, since it is quieter.

>3 ) Just a thought ,would an oil cooler work to keep everything cool 
>? Has anyone added an oil cooler to their Audi ?

Oil coolers are stock on all I-5 turbo engines out of necessity; they 
make a lot more power and dump a lot more heat into the oil courtesy 
the turbocharger.  A friend's 4000 which was on-track at Lime Rock in 
intense heat only hit maybe 120, I think, on the digital bar 
gauge....and it was spending a good bit of the time at very high RPM 
and load.  Given yours is seeing neither...

>4 ) It seems to me that my AC system is cycling through more often. 
>Would this mean my R-12 is getting lower ? And how would I measure 
>that ?

Best to consult an A/C shop on this one.

B
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