Automotive Air Conditioning Information Forum (Archives)

Fixin der Porsche on Mon May 21, 2012 11:48 PM

Year: 1983
Make: Mercedes
Model: 300sd
Engine Size: 3.0
Refrigerant Type: r134a
Ambient Temp: 90F
Pressure Low: 38
Pressure High: 195-237
Country of Origin: United States

Converted this car from r12 to r134a, flushed, new compressor, hoses, dryer, evaporator, txv, switches, BVA 100, dye, filled 80% pure r134a. New R4 Harrison (purchased here) began leaking within 3 months from shaft seal. Removed compressor, local A/C shop installed new shaft seal, no problem for 1.5 year, cooled great here in Texas. Last week, massive blow out, (big green cloud, oil dripping) hissing for several minutes. Discovered half of big housing o-ring on back of R4 compressor blew out!! Front seal is fine. So removed compressor, back at A/C shop, for a new seal kit. Will determine if this is an actual overpressure situation (aux fan not coming on, plugged txv, etc) My question is this: With such a rapid loss of freon and oil, how much new oil should I refill into the system? I do not want to overfill the system with oil for the obvious reasons. I could not drain any oil out of the compressor. Can I assume there is still 1oz in the condenser, and 1oz in the evap? Thanks. M

JJM on Tue May 22, 2012 8:42 PM

The only way to be 100% sure of oil level is to start with a dry system... dump the compressor of oil, flush the evaporator (probably lots there), condenser, lines without filters and mufflers, replace the dryer, then add back the specified amount of oil.

At minimum however, I would dump the compressor, blow everything out with nitrogen, and replace the dryer (they mop up oil). You'll probably have about an ounce of oil or so at that point, then just add the full specified oil amount.

Joe

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