I'll be replacing a condenser coil soon on a 1996 XJS. I will put a vacuum on the system. I know that I will have to charge it up with 33.5 oz of R134a (+/- 1.75 oz).

I don't know how much PAG oil (or what weight) to add to it. I know it has a 4.5 (+/- 0.5) oz capacity. I just don't know how much of it will be lost with the vacuum, and replacement of both the drier and the condenser coil itself.

Some general hunting does seem to indicate that I can expect 3 ounces lost due to the two pieces being replaced, with the final 1-2 oz residing in the compressor itself.

Does anyone have any suggestions, or knowledge on this subject. I've read through the manual and have found the following:

"Typically [2.7 oz] may be drained from the original compressor and [1.0 oz] found in the oil separator; if these quantities are added together - [2.7oz + 1.0oz = 3.7oz]; then this is the amount of fresh PAG that must be put into the new compressor prior to fitting. Please note that this discrepancy between this figure and the nominal capacity of [4.5 oz] is caused by normally unrecoverable oil being trapped in components such as the receiver/drier or evaporator. The previous statements are only valid if there is NO evidence of an oil leak from the system. If oil has been lost and the fault attended to, then the compressor, whether original or replacement, should be filled with the specified quantity."

Whew. I had a leak in my condenser coil. The R134a charge I got lasted me about 1 week. I can't say I even used it all that much since the weather was so pleasant lately.

So ultimately, how much oil could I have lost from a condenser coil leak?

Thanks.

 

Sound like it needs about .5 oz. Remeber you are shooting somewhere between the tolerance, it doesn't have to be perfect. So by adding .5 I believe you would be playing it conservatively, on both sides of the spectrum.