Buying 78 300D

I am looking at a 78 300D. The issue is its my first diesel and I have been told by the owner that the climate control servo needs to be replaced. They have set the servo so the heater works and purged the
system of freon. Here is my issue, after talking to a couple of shops they are saying they would need to upgrade the AC at the price of $900 which would remove the climate control servo. Is there a way around this and can you still buy the old style freon? Other than that this car is in great shape with less than 150K on it.
Thanks in advance.
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YES. This servo / amplifier system is awful and ought to be junked.
Go to www.unwiredtools.com and look at their digital retrofit kit for this application. Their kit replaces the servo and the amplifier, both of the troublesome elements of the OEM climate control system.
I installed one in my '80 300SD and am pleased with its performance.
Hopefully there are no other "modifications" to the climate control system of the car you have in mind.
Are you satisfied with the acceleration of the 300D? If not try a 300D Turbo or a 300SD which uses the same turbo motor.
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T.G. Lambach wrote:

Thanks for the link. I have found a reasonable :) mech. who has been working on these cars for over 25 years and have it in the shop getting checked out today.
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T.G. Lambach wrote:

I've been wondering about this setup. What happens when the heat is off? I mean, is the electric water pump also turned off, or does it push on the closed valve, or does the coolant get shunted somehow? When I rerouted my hoses to bypass the ACC, the only thing I could imagine is that the secondary water pump keeps pumping but that the servo shunts coolant flow. Is that the case?
-tom!
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Last year I had the R-12 Freon "topped up" in my 300SD's and was told that the R-12's cost, though high was not too much higher than the R134a whose price has risen a lot. Price it both ways: R-12 and conversion to R134a.
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On older cars, it is better to stay R12 due to the hose and seals. The hose is the most important part as R12 hose are not dense enough that the R134A will sneak out.
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Tiger wrote:

I had mine converted to R134A about 10 years ago, with original hoses and no leakage problems to date. However, I did the conversion based on the R12 becoming increasingly high price and forecast to disappear. With the way things are now, I'd keep it R12.
Regarding the climate control system, another alternative to consider is replacing the servo with one from Performance Analysis, in TN. They rebuild them and use a lower case made of aluminum, which eliminates one of the main failure modes. Cost is $600, I think, and after the 1 yr warranty, they will fix it for life for $100. As pointed out, this assumes they haven't screwed up and modified the whole climate control system in your car.
Also, I don't think I'd be too excited about this non-turbo diesel. There are 300SD's available from that era that have much more HP, making them more drivable, plus you get a bigger, nicer car for not much more money.
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