It sounds like your charge is wrong. Return your electric fan setup to how it was before you changed anything and see if your performance returns. 20PSi suction pressure sounds like a low charge or a pinched off expansion valve, even on a cool day you should be seeing 25-30PSI if the cabin is pulled down, fan on low, and coil cold. More than likely the extra airflow over the condenser sucked all the heat out of the system and it now does no work.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Could very well be and I need to figure out the proper way to charge this especially because it has a universal parallel flow condenser and an aftermarket electric fan. I don't know how that will effect the charge. The Denso compressor from the M120 appears to be very similar to the Denso compressor from the M117 except the 1996 SL600 the M120 came from was using R134 and the 560SL used R12. The stock 560SL used 1Kg (~36oz) charge of R12. So that would account for about 32 oz of R134 I put in 36 oz when I got my low duct output. I have installed a new expansion valve which as far as I know if the stock R12 replacement valve. That's why I asked you in the other thread if you were aware of an R134 valve for the R107.

The one thing I found it that pressures can be adjusted either by charge or fans. When I first went to charge the system the only fan I had working was the electric radiator fan that would only click on when the car warmed up to about 85°C. Since the car was cold when I first went to charge it I was getting pressures like 375PSI/70PSI and no cold air at all. As soon as I jumped out the fan those came down significantly to the 250PSI/35PSI range. So I can bring both pressures up just by disconnecting fans but where does that leave me with setting the proper charge. In any case I have already tried disconnecting the Aux fan to simulate what I had previously and still have lost the performance.

There is a possibility that I have a leak or had a leak. I just received a new leak detector so I will be using that.

As far as setting the charge I'm going to have to wait until I can send for my brothers recovery station, so I can experiment properly. In the end I really need to get a known quantity of Freon in the system.

As you can see from the attached service manual page, the R107 really does suck for AC. The red line shows where a stock R107 should perform at on a 70° day. But I did have much better than that for a very short period of time.

You do seem very knowledgeable on this subject so I do appreciate your advice.


Thanks
John

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John Roncallo