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  #1  
Old 12-05-2000, 08:20 PM
patsy
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My A.C. Compressor on my '79 300 SD just seized and threw the belt. Can I still drive the car until I repair it?

I see I have the R-4 compressor. It is around 275.00. I will have a tech who filled my system before replace it.

Would it be a good idea if it is possible to upgrade the system to the current refrigerant? If it is possible, what all would I need to replace?

[Edited by patsy on 12-05-2000 at 08:50 PM]
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  #2  
Old 12-05-2000, 10:21 PM
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You can drive the car without the belt. This will not hurt a thing. The only thing you will notice in the winter is a lack of inside defrost mode. The A/C pulles the moisture from the air, so it is turned on to clear moisture from the windscreen.
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  #3  
Old 12-05-2000, 10:40 PM
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If you want to convert to r-134, this is the perfect time to do it. Most of the gear needed for the convertion has to be replace anyways. A good flush of the AC system is in order since your old compressor seized and probably sent "particles" thoughout the system. Do a search on the subject before you decide to convert.
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  #4  
Old 12-05-2000, 11:52 PM
Wm. Lewallen
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A C Compressor

Patsy, you can get a rebuilt R-4 compressor for your car from Auto-Zone for $95.95 and it is guaranted for life. They also have the conversion kits to convert to R134A. Cost $39.95. The kits contain all you will need including three 12 ounce cans of R134A. You can also get the same stuff from Advanced Auto Stores.Cost a little more. Just follow the instructions. It might be a good idea to install a new receiver/drier/strainer with the new compressor. Good luck.
Bill Lewallen Lexington,Ky.
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  #5  
Old 12-06-2000, 12:25 AM
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Not just a good idea to replace the receiver/drier, it is usually recommended anytime you expose the system to atmosphere.
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  #6  
Old 12-06-2000, 08:11 AM
LarryBible
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patsy,

I'm sorry, but I can't keep from offering my unsolicited $0.02 here.

First of all I would highly recommend against a rebuilt R4 compressor. I think Bill has obviously had better luck with them than I have. The R4 does not seem to rebuild well. If it fails it will leave a real mess in the system that will have to be thoroughly flushed when putting another one in. Additionally, for safety's sake, you should flush the system when replacing your compressor this time. Find a new Delco compressor.

Additionally, I cannot tell where you are from. I'm not being nosy, I would just like to know the climate in which you drive. Bill lives in Kentucky and probably doesn't deal with too many 108 degree days. If you live in an extra hot area like Texas, I would not recommend changing this car to R134. You just lose too much cooling capacity, and will sweat for the first ten minutes after you start the car in the summer. I've changed over a few cars to R134, the 123 car does not respond well.

Best of luck,
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  #7  
Old 12-06-2000, 08:45 AM
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I also believe you should change the dryer when you open the system, as many manufacturers mandate. With the age of the car, and the fact that the compressor just failed, it is cheap insurance. Maybe I am over simplifying it, but the desiccant removes liquids from the system, and compressors don't work on liquids. So why risk having liquids in the system on your expensive new compressor? Note I called it a NEW compressor. I have to echo Larry's post on this, and the flushing of the system. Here in Florida, I have seen too many rebuilt compressors replaced after only one season. Spend the extra bucks on a new one, take the time to flush it thoroughly and gain the peace of mind.
(We folks in the toasty climates worry about the a/c more, didja notice?)
My $.02 worth.
Enjoy the work, and good luck!
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  #8  
Old 12-06-2000, 09:10 AM
LarryBible
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I suppose that I overlooked the filter/drier. To me it goes without saying that you replace it whenever doing massive open surgery such as completely opening the system, flushing and replacing the system.

Additionally, you need to evacuate the system thoroughly. If you leave any traces of moisture, it combines with the refrigerant to create an acid which will eat through evaporartors and such. This is much worse in an R134 system. I have a very good vacuum pump now, and on an R134 system I prefer to pump down for 24 hours before charging the system.

Best of luck,
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  #9  
Old 12-06-2000, 10:04 AM
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Patsy:

I replaced the AC Compressor on my 81 300TD this spring. Had a bearing making noise so I got to mine before it seized. YES, get the NEW R4. My parts person doesn't even sell rebuilts - said he had too many come-backs. Got mine for about $240.00. I converted to R134a at the same time (I had done my 71 250C a year earlier). Replaced the receiver/dryer AND the expansion valve ($17.00). The expansion valve is R134 rated.

Other than being a little noisy at high temps (above 100 or so) all is well. I am satisfied with the conversion. Since I have the wagon (and it's black) it takes a little while to cool things off but not too much longer than when I had the original with R12.

Just my .02.

Dan
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  #10  
Old 12-06-2000, 10:07 AM
patsy
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Thanks for all the advice everyone! I was worried that my defrost would not work as well. Unlike other cars, there does not appear to be a way to switch to outside air when running the heat. I will have to leave the dogs at home until I replace the compressor. I live in a 4 season climate. It is very cold here with snow on the ground. In summer it can be 90 degrees with very high humidity.
I have not seen a rebuilt R4 unit in any of my catalogs, for perhaps the reason you state Larry. I will go with a new one.
I will replace the receiver drier with o-rings, and the expansion valve with o-rings.
When my tech evacuates the system, will he reuse the freon? That might help me decide whether to switch to R-134. I paid $30.00 a can for the previous fill.
If I replace the three items(compressor,receiver drier, expansion valve), and I want to switch, will the conversion kit be all I need? Or is there something else I have missed?
I just read, perhaps incorrectly, that a.c. compressors will lock up if the cooling fan is not working properly.

[Edited by patsy on 12-06-2000 at 05:50 PM]
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  #11  
Old 12-06-2000, 10:19 AM
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Location: Sunny Florida
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About the conversion to R134a....
I did mine, and it does take a little longer to cool. Also, I think I replaced the switch for the fan with a different part number for R134 vs R12. R134 operates at a different pressure and requires a different switch to kick the fan on. Please ask one of the techs to verify this though. The gray hairs on my head affect the memory sometimes, so I am not sure it is right.........


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  #12  
Old 12-06-2000, 10:37 AM
LarryBible
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Yes, the switch in the top of the filter/drier that turns on the auxilliary fan should be changed. I have seen this referred to as the trinary switch or something like that. I am quite sure you can get this piece from the Parts Shop.

Again though, if you are in a warm climate, I don't think you'll be happy with an R134 conversion in this car.

Good luck,
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  #13  
Old 12-06-2000, 06:57 PM
patsy
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Has anyone ever replaced just the clutch assembly on an R-4 compressor? I am curious if it is possible to do this with the compressor still on the car while not disturbing any hoses. Would it disturb the oil or the coolant? It appears to be bolted on. It is probably pressed on. Any ideas on that?
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  #14  
Old 12-06-2000, 07:07 PM
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I had the R134 conversion done on my W126 and it sucks at idle. Barely cools at all. Of course, I am suspecting that the valve everyone talks about that allows too much fresh air in that resides behind the glove box is faulty too. I need to check that one out.
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  #15  
Old 12-07-2000, 08:03 AM
LarryBible
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patsy,

First of all, if the temperature where you are doesn't get hotter than the nineties, you MIGHT get by with R134. I still feel that if you will get the system leak free and stay with R12 you will be better off.

In the event that you decide to change to R134, use the green o-rings. These are for R134.

Also, you mentioned the auxilliary fan. It not working won't necessarily blow the compressor, but it is really hard on the compressor. When the fan comes on, it brings down the high side pressure. The R134 system is kind of difficult to get charged exactly right, and the high side pressure can "run away" which loads and possibly blows the compressor.

Best of luck,
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