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Old 07-11-2002, 12:13 AM
can-do can-do is offline
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Join Date: Jan 2001
Location: Tucson, Arizona
Posts: 758
Free of bubbles doesn't mean a full charge

Greetings All,

I can't say I've cured the problem with the 300E a/c not cooling problem, but hopefully on the road to success. Just thinking about it, after adding 12 oz of R-12 freon to the system, it still seemed thirsty for more and the suction and high pressures did go up regardless that I saw no bubbles initiallyin the sight glass. An empty or near empty system will appear full in the sight glass as you see no bubbles in the freon, the view is deceiving and the charge will appear full when in fact if you charge using gauges, it's quite low in fact. I'm gonna let it sit a day or so and let the wife use the air when she wants and see if the pressures change which should indicate a leak in the system somewhere. No oil residue on the lines, so this could be tricky to find without inducing a dye into the system. It may come to that as R-12 is quite pricy to use as a leak detector and hard to see unless oil is expelled with it at the leak point. I'll keep you posted on this one. One thing is for sure, the aux fan really needs to be engaged before 110C unless you have an extremely strong primary fan and clutch system. The small additional heat exchange with the fan does make a huge difference on a/c operation and cooling.

For Bruce out there, I'd say to check for proper operation of you aux fan circuit first then either charge or have charged your system with a dye to locate any possible leaks or seeps in your system. Once it's fully charged again, it should start performing as it was designed. For the time mine has worked so far, it does cool right down, but then again I am using R-12 to do it to.

"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan
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