Might be the case, but doubt it will hurt it, and means longer stretch of time before it will need some added again. If it stops cycling completely, it will be getting warm soon. I'll pass on the old 911's, thank you.

I think mine is under-filled: about 905 grams vs the 950 required. I'll probably check it next month: my 928 ac went out, fixing that first since the 951 still blows cold :)

Mine is a little over now because it ran too low (and therefore warm) before the season was over, and I had to add some more, after filling it once at the start of the hot season here. But it really needs to be working year-round, as it significantly improves defrosting capability.

If you see a continuous stream of bubbles in the sight-glass, then it is definitely under-filled. You should only see them for a few seconds after the compressor cycles on, then they should disappear. This is the reason for having a sight-glass!

i'll look at this tonight: thanks for the tip. :)

Just to add to wild man, the sight glass works OK for R-12, If your car has R134a (OP has R12), the sight glass is not an indicator and most R134a vehicles do not have a sight glass in the receiver-dryer-----new or correct conversions.

GL
John_AZ

Thanks for the FYI, John. I was not aware of that. I must be older-school than I realize.

mark,
did you ever find out the cause of your compressor cycling? I am having the same issue with a similar system story.

Thanks
Pete