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#1
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A/C Questions
I have a '91 Explorer with a malfunctioning (R12) A/C.
Earlier this season the A/C was working, but not real cold. When the temps hit on the 90's, I added my last can of freon. After adding the freon, I found that the compressor clutch was not cycling. The air is very cold, but I am concerned that the system might be overfilled. Questions: How do I test to see if the system is overcharged? How can I check to see if the cycling problem is due to a bad cycle switch? I am assuming that running the compressor at a 100% duty cycle will damage the system. Is this correct? Thanks John Normile |
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#2
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A/C Questions
"John Normile" > wrote in message . .. > I have a '91 Explorer with a malfunctioning (R12) A/C. > > Earlier this season the A/C was working, but not real cold. When the > temps hit on the 90's, I added my last can of freon. After adding > the freon, I found that the compressor clutch was not cycling. The > air is very cold, but I am concerned that the system might be > overfilled. > > Questions: > How do I test to see if the system is overcharged? > How can I check to see if the cycling problem is due to a bad cycle > switch? > I am assuming that running the compressor at a 100% duty cycle will > damage the system. Is this correct? > > Thanks > John Normile I have a hard time getting mine (when fully charged) to cycle off on a hot day. Did you try it early in the morning or late at night? To test my system on my newer Explorer with the other refrigerant (whatever it's called) I use a pressure gauge that came with an A/C recharge kit. Older cars had a "sight glass" and you looked for bubbles when you turned off the A/C. You might have a hard time finding a kit for an R12 system at an auto parts store. eBay perhaps? The A/C on some of the newer Explorers comes on with the defrost cycle and it's my understanding that on some cars once you turn on defrost the compressor will continue to be active until you turn off the engine so my guess would be that it's probably not real bad that it stays on. |
#4
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A/C Questions
Contrary to what you have been told, it is not only possible to overcharge a
system no matter what the temp (excluding extreme cold) but it is possible to introduce enough refrigerant as to destroy the compressor if you are not familiar with the systems and their properties... High side pressures are dependant upon ambient temperature and humidity.... rather than reinvent the wheel, I stumbled arouind in Google for a very few minutes and came up with this http://www.johnnysradiatorshop.com/files/32332467.doc - I scanned through it quickly and think it should answer all of your questions and do so with reasonably good answers... FWIW, low side pressures are "controlled' (not the best word for what happens) by the low pressure cutout switch. The proper way to charge any AC system is by weight of the refrigerant... while you can sometimes get away with a SOTP gauge reference method, this may not be in anyones best interests... I haven't had to work with R12 systems for several years (they are nearly outlawed in Cananda... if you have one and it works - good for ya... if you have one and it don't - this gets gnarly... DIYers are allowed to do things that would have my licence revoked. HTH Top posted - as usual. Somehow the old fool managed to hit "rely to sender" as opposed to "reply to group"... |
#5
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A/C Questions
Does this look familiar?
>My experience has been that if you are adding freon in hot weather it >is darn near impossible to overfill a system. Even on the oldest systems, there is a "best way" to do things.... This "best way" is to charge by weight. Are there guidelines regarding system performance - yes.... But your best results will be by charging by weight.... (Let's not belabour any environmental considerations). We can use the sight glass - the "electronic" sight glass, pressures - temperatures - or a combination of any of these.... None are truly accurate. Guages are for performance testing systems and are not a real good measure of how much of what is in the system.... Look at it this way - there are those of us trying to treat "your" planet with the utmost respect..... the least you couild do is return the favour.... |
#6
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A/C Questions
> wrote in message news:fz7nk.4907$%b7.2710@edtnps82... > Does this look familiar? > > >My experience has been that if you are adding freon in hot weather it > >is darn near impossible to overfill a system. > > Even on the oldest systems, there is a "best way" to do things.... This > "best way" is to charge by weight. Are there guidelines regarding system > performance - yes.... But your best results will be by charging by > weight.... (Let's not belabour any environmental considerations). We can use > the sight glass - the "electronic" sight glass, pressures - temperatures - > or a combination of any of these.... None are truly accurate. > > Guages are for performance testing systems and are not a real good measure > of how much of what is in the system.... Look at it this way - there are > those of us trying to treat "your" planet with the utmost respect..... the > least you couild do is return the favour.... > > OK, for example, my '78 F350 says on the AC compressor how many pounds of R12 it should have in there. So, in order to do it by weight, does all of the R12 need to be evacuated and then replaced? This does not seem to be within the scope of most DIYers. Or is it? > |
#7
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A/C Questions
Yes, the system needs to be evacuated. No... it isn't within the scope of
most DIYers.... And this should be telling you something... I can't speak for the US - in Canada, if you have an R12 system that needs servicing, it will not be an R-12 system when you are done. As an automotive shop, we can't purchase R-12.... Open heart surgery isn't within the scope of most DIYers.... DNA testing isn't within the scope of DIYers.... closer to home - accurate (or properly performed) voltage drop testing... and we can add any number of other operations.... If we are not properly equipped to do something... why would we attempt? If I don't have the proper equipment in my shop to perform a test or repair on your car, will you pay me for the attempt? Look at it this way... how can you ice skate if you don't have a pair of ice skates? "Ulysses" /> wrote in message news > > > wrote in message > news:fz7nk.4907$%b7.2710@edtnps82... >> Does this look familiar? >> >> >My experience has been that if you are adding freon in hot weather it >> >is darn near impossible to overfill a system. >> >> Even on the oldest systems, there is a "best way" to do things.... This >> "best way" is to charge by weight. Are there guidelines regarding system >> performance - yes.... But your best results will be by charging by >> weight.... (Let's not belabour any environmental considerations). We can > use >> the sight glass - the "electronic" sight glass, pressures - >> temperatures - >> or a combination of any of these.... None are truly accurate. >> >> Guages are for performance testing systems and are not a real good >> measure >> of how much of what is in the system.... Look at it this way - there are >> those of us trying to treat "your" planet with the utmost respect..... >> the >> least you couild do is return the favour.... >> >> > > OK, for example, my '78 F350 says on the AC compressor how many pounds of > R12 it should have in there. So, in order to do it by weight, does all of > the R12 need to be evacuated and then replaced? This does not seem to be > within the scope of most DIYers. Or is it? >> > > |
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