A/C Refrigerant Level

[gcw206]

I have looked for the answer to these questions, but cannot find them;
I have a 1969 280SE W111 Coupe, with a Kuhlmeister under dash A/C unit.
When I bought it, it had been sitting with little use for many years.
I turned the A/C on, and no cold air.
The system was 100% empty (a zero reading on both the high and the low gage).
The compressor crankcase has the proper level of oil.
How much refrigerant and how much lubricant do I add to a completely empty system?
Also, where is the expansion valve located?  Must I drop the dash mounted unit?
Thanks,
GCW

[doitwright]

Start here https://youtu.be/QO1rH8Xzbtc

Expansion valve is on the back of the evaporator.

[Nicolas Aristodemou]

GCW first you should determine if the car is (was) running on R134 - should be- else
, if running on R12 which is no longer available you would have to take it to an AC specialist to remove the R12 and charge with R134 (probably replacing the filter dryer at the same time).

I think a specialist shop would be your best bet actually since they have automatic machines that not only test the vacuum on your system but can insert the appropriate amount of oil and refrigerant. These machines can also add a tracing dye to help pinpoint any leaks.

The amount of refrigerant should be anywhere between 700-900 grams, the specialist would know.

I think trying the DIY approach would not get you far and you will end up going to a professional in any case in the end...