Oil leakage observed at AC coolant line at bonnet -- too cold to run unit

Came across something a bit puzzling in last evening’s inspection I’ve not encountered before.

The house had a relatively old AC condenser (evidently manufactured in 1987 per serial # and style, round Comfortmaker design as common around then), and the outside air temperature was about 50F, too cold to run it. The fan blade turned easily when pushed with a twig.

When looking at the furnace/blower unit, I noticed what looked like a water spot on the floor that turned out to be some sort of oil, which I then saw was dripping from the coolant line where it exited the bonnet.

So, my questions for AC specialists:

What’s going on here?

Does this have any implications regarding the performance of the unit?

I intend to report the unit as more-or-less at the typical life expectancy of such a unit and likely to be considerably less efficient than a more modern unit, and recommend a servicing checkup by a licensed specialist anyway, but I am curious as to the significance, if any, of this.

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Frank I would like to help you get your terminology going in the right direction I don’t understand what you are calling a bonnet in the pic I see the suction and liquid refrigerant lines entering and exiting the A-coil plenum box. And to answer your question yes if there is refrigerant oil dripping from the line set which also means that refrigerant is also leaking from the system and the unit would not function properly. The remaining refrigerant if any would be required to be pumped down and retained in the exterior condensing unit. The leak on the suction line repaired, a vacuum pulled on the line set and the A-coil and the system re-charged with refrigerant. In Oklahoma that would be approximately $350.00 repair job. Ca about $650, If a NY engineer repaired the leak cost would be about $850.00:D;-)

Try a little more explanation with clients.


… and budget for replacement due to the age.