question for the air conditioning guru's......

1993 lincoln t.c. - had LOTS of idle time with a/c running when father was alive. he had cancer, wanted to get out of house, but he didn't want to go into a store, so, he would stay in car, while we shop.
a/c compressor got noisy but still operated fine - for years.
just got use to it. knew it was worn and it didn't go with the miles on car which is why i had to explain the extra wear.
was driving along and noticed a temp rise in car. checked it out. a/c compressor wasn't coming on due to low pressure cutout switch not engaged.
as i was charging the system and high pressure safety valve blew open and discharged gas until it dropped in pressure.
so, what's the verdict? i know a new compressor in one item that is needed, what i don't have... is the working knowledge to know the different problems and symptoms about the system.
what usually causes the high limit safety to open up? logic says that it's got too much pressure build up but i guess what i'm asking is what should i be looking for in checking out the system, giving this symptom.
the system was not overcharged. that's for sure.
here's some basic questions.....
i know that when you have a home a/c unit and the compressor does a burn out, the system has to be flushed and the oil turns to acid due to the reaction with the windings burning out of it and if you don't react fairly quckily, the lines will be eaten.
but on a car, you don't have that problem, but you can have a mechanical failure internally. so, my question is what happens when this happens. that is what my guess is.
thanks in advance.
~ curtis
knowledge is power - growing old is mandatory - growing wise is optional "Many more men die with prostate cancer than of it. Growing old is invariably fatal. Prostate cancer is only sometimes so." http://community.webtv.net/PALMER_ENT/doc
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Overly high pressure on the high side can be caused by too much air in the system, or by a clogged orifice tube or other component. Did you happen to recharge the system with a can of R-134 that includes stop leak?
Unless you hooked up gauges to the high & low sides while you were charging the system, there's no way you can be certain that the system wasn't overcharged.
I'm kind of surprised that the system vented due to high pressure. Usually there's just a high pressure switch that shuts off the compressor when it gets too high. You should have a professional look it over if you intend to keep using the A/C on this car.
Bob
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Bob Bailin wrote:

In early 1993 the Towncar still used an R-12 system. There was no high limit switch, just a relief valve on the compressor.
The most likely scenario is this: Over time, the noisy compressor shed metal debris in the system clogging the orifice tube. The system vented due to the high head pressure and was likely empty and full of air because the relief valves often don't reseat completely. When the R-134 (improper refrigerant) was added to the air currently in the system, the head pressure shot up and the vent valve opened again. You have had a catastrophic compressor failure, known as black death. The recommended repair is replacement of everything in the engine compartment. Compressor, condenser, accumulator, lines, and orifice. Here's a good article on the subject: http://www.ackits.com/index.cfm?fuseaction=black%20death It doesn't mention replacing the condenser, but experience has shown that Ford condensers usually cannot be flushed sucessfully due th their design. The flush solvent will bypass around plugged areas. Due to the expense and the age of the car, I usually recommend a new compressor (no reman), new accumulator and orifice. The lines and condenser can be obtained from a scrapped vehicle with an intact AC system that has not had a compressor failure.
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thanks for the responses - i will answer them as follows...... ========
Overly high pressure on the high side can be caused by too much air in the system, or by a clogged orifice tube or other component. Did you happen to recharge the system with a can of R-134 that includes stop leak?
Unless you hooked up gauges to the high & low sides while you were charging the system, there's no way you can be certain that the system wasn't overcharged. I'm kind of surprised that the system vented due to high pressure. Usually there's just a high pressure switch that shuts off the compressor when it gets too high. You should have a professional look it over if you intend to keep using the A/C on this car. Bob
======> hi bob - it is an old R-12 system and i still had some r-12 laying around. just putting the gauge on the suction side, i had less than 5 lbs, so it was obvious the system was low. as i was putting the first can of r-12 in, that is when the compressor blew the high relief. so, i stopped right there, and didn't go any further. hence, the reason of why i'm writing the post.
------------
From: snipped-for-privacy@swbell.net (JW)
Sir, You've no doubt heard the expression " a little knowledge is dangerous" ? Automotive AC systems are complex to the average person and if one item or procedure in a repair is skipped or done incorrectly, very expensive components could be damaged beyond use. With this said, it would be advisable to leave the repair to a trusted professional. Don't take this wrong...I'm just trying to save you some time and a lot of money. ====> hi jw - i do appreciate the input and your statement, " a little knowledge is dangerous" sums up my knowledge in this area. yes, i have the basics, but not enough to make a living at it. that is why i posted the symptoms and the questions.
thanks again for the input.
--------------------
In early 1993 the Towncar still used an R-12 system. There was no high limit switch, just a relief valve on the compressor. The most likely scenario is this: Over time, the noisy compressor shed metal debris in the system clogging the orifice tube. The system vented due to the high head pressure and was likely empty and full of air because the relief valves often don't reseat completely. When the R-134 (improper refrigerant) was added to the air currently in the system, the head pressure shot up and the vent valve opened again. You have had a catastrophic compressor failure, known as black death. The recommended repair is replacement of everything in the engine compartment. Compressor, condenser, accumulator, lines, and orifice. Here's a good article on the subject: http://www.ackits.com/index.cfm?fuseaction=black%20death It doesn't mention replacing the condenser, but experience has shown that Ford condensers usually cannot be flushed successfully due to their design. The flush solvent will bypass around plugged areas. Due to the expense and the age of the car, I usually recommend a new compressor (no reman), new accumulator and orifice. The lines and condenser can be obtained from a scrapped vehicle with an intact AC system that has not had a compressor failure. =====> thanks tom - i was afraid that it would probably end up in this direction. you did a great job explaining it.
my only concerns now is two fold. one, i have another vehicle that has a complete working a/c unit on it that is going to be stripped for the junk yard, so the cost is not going to be a problem.
the second question is that do i want to replace everything under the hood on the a/c side?
there's no sense in doing just a half ass job and then, only have it last a few months due to lousy installation - when i knew better.
the third option is that i can use the car mainly in the fall and winter months where a/c is not a problem.
being that it was my dad's car is the only reason i am even pondering these thoughts.
any other car or truck, and my choice would have been an easy decision.
thanks again for all that replied.
~ curtis
knowledge is power - growing old is mandatory - growing wise is optional "Many more men die with prostate cancer than of it. Growing old is invariably fatal. Prostate cancer is only sometimes so." http://community.webtv.net/PALMER_ENT/doc
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c palmer wrote: "...my only concerns now is two fold. one, i have another vehicle that has a complete working a/c unit on it that is going to be stripped for the junk yard, so the cost is not going to be a problem."
If the other car is a Town Car, Crown Vic, or Grand Marquis of close to the same model year visually compare the parts. They are extremely similar and may be identical. If everything will fit, you're in business. Do buy a new accumulator, though. It's roughly comparable to the oil filter on your car, a wear item.
"the second question is that do i want to replace everything under the hood on the a/c side?"
Yes, everything from the firewall foreward. Anything less is asking for a repeat failure in a case like this. If you have a parts car...
"there's no sense in doing just a half ass job and then, only have it last a few months due to lousy installation - when i knew better."
Very true. It's unfortunate that the AC system is one of the most misunderstood systems on a vehicle. Very few "shortcuts" are possible and proper repair can get really expensive. Even moreso after a poor repair. If you decide to fix it, it is very doable DIY with the proper guidance and a little bit of mechanicl knowledge. I would suggest starting here: http://www.autoacforum.com /
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Sir, You've no doubt heard the expression " a little knowledge is dangerous" ? Automotive AC systems are complex to the average person and if one item or procedure in a repair is skipped or done incorrectly, very expensive components could be damaged beyond use. With this said, it would be advisable to leave the repair to a trusted professional. Don't take this wrong...I'm just trying to save you some time and a lot of money.

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Not to disparage those ACTUALLY of that ilk... but how do you find them?
Like my brother did, while on vacation in Florida and his Suburban's A/C quit?
"Sorry, you have a >>>plugged condenser<<... we accept Master Card and Visa" - Note he wasnt billed for any other parts, only refrigerant and a condenser.
No, what BEST is to find a reputable service point for all your systems ahead of time.
Always get the diagnostic in writing and ALWAYS take the old part.. making sure it's the same one.
Exactly why I learned the systems and do it myself, A/C service is full of crooks and idiots.
--
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
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