Need advice on a 300SDL A/C condenser replacement. The A/C condenser was leaking and I changed it out with a used one from the junk yard. Changed out the receiver driver as well and I vacuumed it down to about 5 in of mercury as per the gauge and let it sat.

The system leaked and lost the vacuum in about 5 hours. Most shops probably would check vacuum is held for about 15 minutes.

Q: Is it OK to recharge it or I need to find the minute leak.

Any advice would be welcome. BTW, I will be recharging it with R134a as it was converted already by previous owner.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Yes, you must find and fix the leak.
The good news is you may can FIX it from the outside depending on where the leak is.
You are allowed by the rules to put a few ounces of some refrigerant (check the epa rules) for the purpose of leak detecting. Borrow one of the leak detectors that will react to that refrigerant... then consider cleaning that area and using JBWeld to hold a brass patch on it.. the brass should not touch the metal on the condenser.. it is just a top layer for the epoxy. Follow the rules on the epoxy. Do not rush the situation.
Then recheck for leaks. Use the slow Epoxy if you have a choice.. usually much stronger... once in place do not touch it. Keep it above 70 degrees with a light if necessary. The brass does not have to be thick... 10 thou shimstock is just fine.
Hollar if you have any questions.