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  #16  
Old 07-10-2002, 10:44 AM
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Join Date: Jan 2001
Location: Northern Virginia
Posts: 46
I'm sure this sounds way silly to everyone, but have you ensured that your aux fan is running? mine didn't and A/C would only blow warmish air. Everythiing else in the systme seemed ok. turned out to be a bad balast resitor to the aux. fan. Replace it for a few bucks and now the thing frezzes me out. But I'm sure you guys already covered that, just ignore me in that case.


Take care
Evan
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  #17  
Old 07-11-2002, 12:13 AM
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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.

Charles
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"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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  #18  
Old 07-11-2002, 12:19 AM
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Join Date: Mar 2001
Location: Evansville WI
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The view inside the receiver/drier window was the point I was first trying to make, it's hard to tell full from empty when the glass is cleaned off. But you said you saw bubbles, so I assumed it was at least near enough to not be a big issue.
Gilly
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  #19  
Old 07-11-2002, 12:31 AM
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Join Date: Jan 2001
Location: Tucson, Arizona
Posts: 758
looks Full on Low Charge

Greetings Gilly,

If the person working on the a/c doesn't have gauges hooked up to the system, during initial start up and running of the a/c system the glass will appear full of bubbles and then go to a full coat of freon on the sight glass, not empty looking. This is where the gauges must come into play as they will give you a better estimate of just how much freon is in your system. Yes, you can look at your sight glass with the system off verses on and running and it will apppear full, but the pressure in the system tells you different. I was just determined to either blow the sob up or charge the system to operating levels. A full sysytem will not draw freon into it like a kid sucking on a malt, and that's how my system reacted once I induced freon to it. So yeah, don't trust your sight glass as it will not give you a good representation of how full your system is. Lesson learned, hook up the gauges and don't trust your vision.


Charles
__________________
"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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