What was the pressure at idle?

At 40/ 440, looks like there is a restriction somewhere. The expansion valve is a common place to clog.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

I know you said you vacuumed down to -29, but those numbers could be also indicative of air in the system. When you vacuumed down the system did you do it for at least 15 - 30 mins on low and hi side? Also, before you started charging, did you crack the yellow feed hose first to purge the air out and let the r134 fill up the hose before you introduced the refrigerant into the system? I would say vac the system down again and follow the recommended charging protocol. Or, try getting the rpms up to about 2500 and see where you are at with ac vent temp and the high and low side pressure. If it stabilizes at the higher rpm and then goes back up, you could have a problem with the compressor not properly compressing the refrigerant.
Also, check out this attachment. Good luck.

Attached Files

AC troubleshooting.pdf (485.1 KB, 169 views)

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1990 190E 3.0L

at 450 psig with runnign system your liquid line should be extremely hot, try dousing the condenser with running water and see if it helps.

In one instance in a another brand car I was repairing this behaviour was caused by a faulty expansion valve - its high side was reaching 400 psi while the low side was at 30 and going towards 20 when revved.

It maybe that you have a lot of oil in the system.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Just finished up -- it was either excess oil or a blockage. I flushed the entire high side from condenser to TVX and the evaporator. Replaced expansion valve and receiver drier.

and Success, or about the limit of R134a in my climate!....Definitely either flushed out excess oil or removed any blockage.

I got about 24-26oz estimate in. That is about 6oz short of what the factory manual states, but any higher was outside my comfort zone for pressures. In cooler climates I would have added more for sure. Final pressures 55psi low 375psi high. Ambient temp is 112F. Getting 48F out of the center vents on the quick drive I made. Rises to about 55F at idle. I expect on the freeway it'll get down to the low 40's.

I think that's about the limit of R134a in this climate! Either way it'll last me the rest of the summer and once I put the new evaporator, heater core, compressor RD/TXV and R12 in, I should see even lower vent temps and lower pressures.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Congrats! I agree with your assessment regarding the maximum efficiency of your system.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Awesome. Thanks for the update.

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1990 190E 3.0L

There is no need for scientific grade equipment. A good vacuum gauge as listed above would be swell. Anything that holds under 500 microns is considered a tight system.

Really for automotive systems, under 800 is great.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2