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Re: C-3 Air-conditioning , How many Lbs of R-12
Not knowing what has been done to your system other than you adding R-12, and I am not a air conditoning repair person, I do recommend this from experience. MY 70 wasn taken to a Chevy dealership in 1988 for air not cooling. The Chevy techs said I needed a new evaporator. They tried to disconnect the biggest connector to the evaporator and could not. They drilled into the top of the connector nut but not into the evaporator tube in an attempt to disconnect the evaporator. This procedure didn't work and they stopped working on the problem. I was out of town during this and when I got back home I read my service manual and from what I learned reading it I checked the removable screen and discovered it was very much full of desicant from the dryer. Replaced the original dryer and flushed the line to the screen, installed a new screen, and had the system evacuated and recharged with R12. Its still working today. This may not be your problem but it is one of the easiest to check. An easy out comes in handy in retracting the filter screen. It doesn't take much contamination to block this very small filter screen. -
Re: C-3 Air-conditioning , How many Lbs of R-12
Dave
three pounds to an empty system
jerComment
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Re: C-3 Air-conditioning , How many Lbs of R-12
Dave - I have done a fair number of AC repairs and charges but not on my vettes. I am assuming you have used proper procedures to evacuate the moisture with a vacuum pump for 15 minutes or so before charging. It is always best to replace the dessicant bag and clean or replace the debris screen. Usually, the units shut down from low high side pressure, you do not mention the high side pressure just the low side...are you using a single guage or a set? The 28-30 sounds good for the low side, but, it sounds like it is taking too long to reach that...I usually see that happen in 10 seconds or so from my experience. I also have observed that low side readings are reached long before the correct charge is in place and I go by both the low side and high side pressures, and the ambient inlet temperature and the outlet temperature. The engine should be at around 1500rpm, and the AC on full. I usually also check the air temp coming out of the center vents.....most GM systems can get this down to the high 30 degree range, but vettes are challenged as I recall in the upper 40's if you look at the service manual. Also, is your system the later radial 4 cylinder design or the earlier axial 6 cylinder Fridgedaire? Seems like this change happened around 1977. If you have some aftermarket parts such as larger dryers etc, it may affect the charge, but it bothers me 3lbs is not sufficient...other car systems were 3.5 or so. This may be a stupid question, but, are you weighing in the charge from a 30lb cylinder, or, are you using the cans? Remember, the cans are 12 ounces, not 1lb cans, so 3lbs is 4 cans....just for grins.....good luck!...CraigComment
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