Since starting this thread, I had some more R12 added by a fellow club member and he checked for leaks with a sniffer but found none. He did comment that the low side pressure seemed too low relative to the high side suggesting there could be a blockage in the system, possibly at the TX valve. At the time the cooling performance was poor.

The following day I found the cooling to be quite good although I suspect it could still use more R12 (some bubbles in sight glass). I have been observing the behaviour throughout our summer and for much of the time the cooling performance has been adequate with the compressor and aux fan cycling on and off as expected. I do however find that after an extended period of use that it appears to stop cooling, despite the fact that the compressor continues to run (without cycling off). Sometimes switching the system off for about 10 minutes will allow it to operate again when it is again switched on. I am puzzled by this behaviour and wonder if it could be due to a blockage.

Whilst doing an engine oil change on the weekend and using the opportunity to check everything in the engine bay and underneath, I noticed an oil leak at the receiver-dryer. It is covered with a clean, almost sticky oil which I can only assume is compressor lubricant. I also noticed a slight leak of the same oil at the compressor. I know it is not engine oil as it is very clean whereas the engine oil was much darker being due for a change. The oil on the compressor appears to have leaked from the manifold where the refrigerant lines attach rather than from the shaft and clutch area. Are there O-rings or something here that can leak?

Would it be reasonable to have the system emptied, replace the receiver-dryer and the O-rings at the manifold on the compressor, and then re-gas or should more extensive (and expensive) repairs be undertaken? Pressumably more oil will also be required to replace that which has leaked. How does one know how much oil to add? Any thoughts would be welcomed.

Thanks,
Greg

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