1991 Cadillac Deville Lesalle A/C not working!
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1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, 1991 Cadillac Deville Lesalle A/C not working! in Past Cadillac Vehicle Discussion; Great message board! Our son & dauther-in-law bought us a 1991 Cadillac Deville Lesalle Series from an individual. Engine is ...
  1. #1
    robtpala is offline Cadillac Owners Member
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    Red face 1991 Cadillac Deville Lesalle A/C not working!

    Great message board! Our son & dauther-in-law bought us a 1991 Cadillac Deville Lesalle Series from an individual. Engine is a 4.9. FWD. Great looking car! They were able to get a slight price break because the "A/C needs servicing" light comes on. I told them that I would pay to have the system recharged. The light is correct because no cold air comes out of the vents and the a/c compressor does not come on.

    How do we get the compressor to come on to add the freon? I believe I read somewhere that this can be done using the heater/ac control buttons. Is this correct or do we need to do it the old fashion way. (By-pass low freon cutoff switch)

    I understand that this car requires R12 freon. Can we use the newer Freeze 12? If we can not use Freeze 12 can we convert the system to use R134 without having to purchase a new compressor? Someone has told us that we can not use R134 using our compressor. The problem being that the lubricant in the compressor which we now have will not work with R134. False Info?

    All of the servicing will be done by a licensed A/C specialist, he just doesn't know exactly what works best on this car. He thinks it is not wise to convert to R134 without a new compressor but can use Freeze 12 with this compressor.

    Thanks in advance.

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  3. #2
    youbetcha77's Avatar
    youbetcha77 is offline Cadillac Owners Connoisseur
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    Im running the R134 in my car. I do not see any reason why the Ester Oil, used with R134a, will not be compatible with the r-12 or the oil in there. When adding freon turn the can upside down and liquid will go in. This will cause the compressor to start cycling in and out. The longer you hold it upside down the shorter the cycle until it stays on. At that point you need to start filling it right side up. It is a lot easier and a lot easier on the compressor to just jump the low pressure sensor with the battery cable unhooked and then rehook the battery and add your freon.

    Blaze

  4. #3
    robtpala is offline Cadillac Owners Member
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    Can R12 and R134 be mixed or does the system need to be evacuated?

  5. #4
    youbetcha77's Avatar
    youbetcha77 is offline Cadillac Owners Connoisseur
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    The R-12 does need to be evacuated, but the oils are compatible. A lot of people have mixed the two. It forms a chemical action that eats o-rings and damages compressors. I would have the r-12 evacuated and then re-charge it with the R134.

    Blaze

  6. #5
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    klebrun is offline Cadillac Owners Fanatic
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    I've heard that the r-12 and any moisture has to be completely drained out of the system, since r-12 and r-134 can't be mixed. I don't think the compressor oils are compatible either. I've also heard that the accumulator/dryer (something along that line) has to be changed out as well. Youbetcha's statement seems to disqualify that info. Sounds like he got it to work without all of the hoopla. I have no real world experience in converting a system over, so maybe I've been misinformed.

  7. #6
    youbetcha77's Avatar
    youbetcha77 is offline Cadillac Owners Connoisseur
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    AS long as the R-134a oil you are going to put in is Ester oil, then it is compatible. Only the Ester oil is though. It is a good idea to go ahead and replace the o-rings while your doing this. They are inexpensive and will prevent any freon loss. Systems that leak on a regular basis draw in moisture, then they recharge it in the spring and it draws more moisture. The cycle continues until the compressor finally shoots the crap. Then they say, no problem, ill get a used compressor. So they do and have that installed and then dont take the extra money ro get the system flushed and the metal particles from the first failing compressor kill the second one. My advice to anyone doing the A/C is to replace the orings. There are some where the line assembly fits onto the compressor and anywhere on the lines you see fittings. Ford has to have a special socket looking thing to get them apart, but they are cheap cheap cheap and they are the same ones for the fuel lines, just different size. The receiver/dryer doesnt need to be replaced unless it was plugged up, which would show when charging by the pressure. If you are going to replace O-rings then I would get a new Receiver/dryer and a new Orifice, its a metering valve with screen that fits into the line. That way you wont have any problem. Also after you get it all together again, have the system evacuated. If there is debris in the lines then it needs flushed. Evacuating and flushing are two different things. My A/C machine does both but the flushing requires a chemical.

    Blaze

  8. #7
    Katshot's Avatar
    Katshot is offline Cadillac Owners Master
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    This is a GREAT source for info on doing the retrofit. They have great links.
    http://www.epa.gov/ozone/title6/609/.../retrguid.html

  9. #8
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    Ranger is offline Cadillac Owners Member
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    My understanding is that R12 & R134a (pag 150) oils are not compatable. To do the job properly the system should be flushed. The accumulator/dryer should be changed as it will retain the old oil. The "O" rings need to be changed. The compressor does not need to be changed but should be removed, drained and flushed. The system should be refiled with the same amount of R134a as was recommended for R12.

    The Service A/C light sets a code and disables the compressor to protect it. Before adding refrigerent you must enter the diagnostics and clear the codes to enable the compressor. Do this when everything is hooked up and ready to recharge so the compressor will draw refrigerant in before the code resets.

    I would not use anything but R12.

  10. #9
    youbetcha77's Avatar
    youbetcha77 is offline Cadillac Owners Connoisseur
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    R-12 Oil and Ester oil are compatible. I am certified and have done this for a living. There are other oils out there that different manufacturers use with the R134A. If it isnt ester oil then dont use it. As Ranger said, other oils are not compatible. Only ESTER OIL. If you are buying your stuff from Wal-Mart and are doing it yourself, then you should be okay. Interdynamics, Prestone, Igloo, Honeywell chemicals all use ester oil with their R134A products.

    Blaze

  11. #10
    DaveSmed's Avatar
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    Regarding the accumulator.... changing it is a good idea regardless since it contains the descicant that removes any residual moisture from the system. It also stores quite a bit of the oil, which since your ADDING the ester oil, some of the old mineral oil has to come out somewhere. Moisture equals a quick demise to an A/C system. It reacts and forms an acid (hydrochloric if im not mistaken) and will quickly corrode the aluminum tubing used throughout the system. How to get rid of the moisture? Pull a strong vacuum (29") and hold it. This will boil out any residual moisture from an opened system due to the major drop in waters boiling point when subject to a vacuum. The vacuum is also an excellent check for leaks. If the vacuum holds, the system is sound.

  12. #11
    youbetcha77's Avatar
    youbetcha77 is offline Cadillac Owners Connoisseur
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    Re: 1991 Cadillac Deville Lesalle A/C not working!

    The moisture doesnt form a acid, it just messes with the freon and the heat exchanging properties. It would be like if you got moisture running in your engine oil, just without the hydrocarbons. It wears out the compressor and corrodes orings and not to mention corrodes the aluminum. The moisture doesnt boil off with just a vacuum pump hooked up to the system, The pump will have to be hooked up long enough to evaporate the moisture. Depending on how much moisture is in there that could take a long time, but there is a faster way. Most of your shops will evacuate the system and then recharge it with a third of its capacity and then quickly evacuate it again. The freon will take most of the moisture out with it. A A/C machine like mine can then filter the freon and remove the moisture and return it to a virgin-like state. I have seen some systems recharged with some oil and R134A and work for many years and I have seen some last a couple months. To do it right and not have to worry replace the O-rings, Receiver/dryer, Orifice or expansion valve screen, and the shrader valve cores. If you have it professionaly flushed, like what my machine does, then most of the oil will be gone as well. Your A/C people will know how much oil and stuff to put in it.

    Blaze

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