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94' Deville 115k
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7 Posts
Discussion Starter #1
I have a 94' Deville, 4.9L with 118k on it and have had to replace the A/C compressor twice now.Yesterday when I disconnected the bigger hoses on the right of the radiator(i believe are A/C hoses)the lower one leaked black oil.Back when I replaced the last pump about 6 months ago I thought I added the Lubricant and some refrigerant but when i disconnected the hoses there was no pressure.Im wondering if I added this stuff in the wrong place and is this oil the lubricant?I was by passing the switch and engaging the clutch manually hoping that this would help circulate the oil but not sure if this was right.Im desperate for advise here .Any advise would be great, also maybe some ideas on why i cant get my pump to kick on.Thank you..!
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
Black oil is not good. Unfortunately this usually means that a full flush of the system and replacement of the Dryer/Accumulator and Orifice Tube is in order. This condition is known as Black Death.

The Compressor is most likely shot. You probably also have some sort of leak. (could be the compressor seal?)

One of the harder things to do is determine the correct amount of oil in your system. Most of the recommendations you are likely to get suggest adding a can of oil whenever you recharge the system. Today's AC systems are designed to use as little refrigerant as possible. This means minimal system capacities. The oil amount is CRITICAL on these cars. To much oil will cause damage just as quick or quicker than not enough. I have seen a pump destroyed in less than 3 or 4 minuets due to overcharging with oil.

The problem is that you can never be sure how much is in the system without a complete drain and flush. (how many times has someone added a can of oil wile recharging) Oil also does not always leak out with the refrigerant leak. (a slow leak a high in the system may not leak any oil at all wile the same leak low in the system may leak a lot of oil)

This would be a great time to do an R134a conversion the right way. To do this correctly requires the complete flushing of the system, Replacement of the Dryer/Accumulator, Replacement of the Orifice Tube, Replacement of the Compressor, replacement of the Condenser with a R134a type , and possible replacement of the rubber lines. (R134a uses a different configuration of condenser than R12 and higher pressures from the Compressor and older lines are sometimes incompatible with R134a)

You should not bypass the pressure switch for more than a moment or two. Refrigerant is needed to carry the oil in suspension. The pressure switch makes sure there is enough refrigerant to carry the oil to the compressor. Without this, The compressor will be starved of oil and will disintegrate.

Unfortunately this repair is expensive. You can save a lot of money by searching for parts bargains on the net. I replaced the condenser, Accumulator,Orifice Tube, and compressor on a Lincoln Town car belonging to my father and the cost for the parts was under $220. All new.
 

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2010 DTS
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87,941 Posts
aeronca is right. Your first compressor failed and left debris in the system. You didn't flush it and it took out the new compressor. Not only do you need to replace the orifice tube and the accumulator, but also the condenser as they are almost impossible to flush. Every remaining line then needs to be flush to avoid another failure. There are no short cuts in A/C service.

A FSM will tell you how many oz. of oil to put in each component when you replace them.
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
One advantage you have is when a car get over 20 years old, Manufacturers tend to start to surplus there parts inventory. Some careful searching on the internet can yield significant savings. I use this surplus time to collect parts i may need to keep my cars running for years in the future.

I just bought 4 Crankcase Depression Regulator Valves for my diesel. They are NLA. Picked them up for under 5 dollars a piece. They used to go for about 50 dollars each. Bought a new A/C Compressor for $59.00. Normally $360.00 and on it goes.
 

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94' Deville 115k
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7 Posts
Discussion Starter #5
Thx for the replies.Since this is my only car for work I guess I will have to go on the search as I drive it and hope it will last.Bummer thing that the 94' pump only fits a 94'.I just bought the only used one around.I am so tempted on removing the pump if I can ....any one ever heard of this for the 4.9?Is it possible to just get a shorter belt?Again Thank You..
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
leave the pump on and just disconnect the clutch plug. Will work as an idler all day long as long as the clutch bearing is good. This bearing has no connection to the pump internals.
 

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03 STS
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2,527 Posts
my 96 a/c slowly died. took a few years. bad compressor. threw on a $50 used one and a/c blew ice cubes. for a month. used new sealing o-rings too. old system never leaked freon. so compressor is bad. this spring i will break down and buy a remaned unit.
 
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